HomeMy WebLinkAboutItem 5B 3139 7th St Memo 05.01.24MEMORANDUM TO THE LANDMARKS BOARD
May 1, 2024
STAFF
Brad Mueller, Director of Planning and Development Service
Kristofer Johnson, Comprehensive Planning Senior Manager
Chris Reynolds, Deputy City Attorney, City Attorney’s Office
Marcy Gerwing, Principal Historic Preservation Planner
Clare Brandt, Historic Preservation Planner
Aubrey Noble, Historic Preservation Program Coordinator
Meron Shiferaw, Historic Preservation Intern
CONSIDERATION OF DEMOLITION APPLICATION
Public hearing and consideration of an application to demolish a house and accessory building
constructed in 1938 at 3139 7th St., a non-landmarked property older than 50 years old,
pursuant to Section 9-11-23 of the Boulder Revised Code, 1981, and under the procedures
prescribed by chapter 1-3, “Quasi-Judicial Hearings,” B.R.C. 1981.
Address: 3139 7th St.
Legal Description: LOTS 34-35-36 BLK 29 NEWLANDS
Case Number: HIS2024-00045
Owner: 3139 Seventh Street LLC, represented by Margaret Freund
Applicant: Kyle Plantico, RHAP Architects
Case Type: Non-Designated Demolition
Code Section: 9-11-23, B.R.C., 1981
EXECUTIVE SUMMARY
In March 2024, the applicant submitted a demolition application for the 1938 house and
accessory building. The Landmarks Design Review Committee referred the application to the
full Landmarks Board, finding “probable cause the property may be eligible for landmark
designation.” The purpose of this hearing is to determine whether the buildings are eligible for
designation and to consider the cost, condition, and relationship to the surrounding area.
Item 5B - 3139 7th St LB memo 05.01.2024 Page 1 of 63
After subsequent research and analysis, staff considers that while the buildings at 3131 7th St.
are largely intact to their 1938 date of construction, the property lacks sufficient historic,
architectural, or environmental significance for individual local landmark designation. Staff
recommends the Landmarks Board approve the demolition request.
STAFF RECOMMENDATION
Staff recommends the Landmarks Board approve the demolition request.
RECOMMENDED MOTION
Issue Demolition Approval
If the Landmarks Board finds the buildings not eligible for individual landmark designation
based upon their historic, architectural, and environmental significance, staff recommends
the following motion language:
I move the Landmarks Board adopt the findings of the staff memorandum dated May 1, 2024
and approve the demolition application for the buildings at 3139 7th St., finding that the
buildings to be demolished do not have significance under the criteria set forth in section
9-11-23(f), B.R.C. 1981.
ALTERNATE MOTION
Issue a Stay-of-Demolition
If the Landmarks Board finds the buildings may be eligible for individual landmark
designation based upon their historic, architectural, and environmental significance, staff
recommends the following motion language:
I move that the Landmarks Board issue a stay-of-demolition for the buildings located at 3139
7th St. for a period not to exceed 180 days from the day the permit application was accepted
by the city manager in order to explore alternatives to demolishing the buildings.
A 180-day stay period would expire on September 30, 2024 (180 days from April 3, 2024, when
the Landmarks Board review fee was paid).
BACKGROUND
•On March 18, 2024, the Planning & Development Services Department accepted a
demolition application for the house and accessory building at 3139 7th St.
•On March 20, 2024, the Landmarks Design Review Committee (Daniels, Decker,
Gerwing) referred the application to demolish the house and accessory building to the
Landmarks Board for review in a public hearing, finding there was “probable cause to
believe that the property may be eligible for designation as an individual landmark.”
•On April 3, 2024, the applicant paid the Landmarks Board hearing fee.
Item 5B - 3139 7th St LB memo 05.01.2024 Page 2 of 63
PROPERTY DESCRIPTION
Date of Construction: 1938 1
Zoning: RL-1 (Residential-Low 1)
Lot Size: 9,437 sq. ft. (Boulder County Assessor estimate)
Building Size (House): 926 sq. ft. (Assessor estimate of first floor above ground finished)
The property is located midblock between Evergreen Avenue and Forest Avenue in the
Newlands neighborhood in north Boulder. The house faces east onto 7th Street. An alley runs
north-south at the rear of the property, however the garage is accessed via 7th Street. The
property is not within the boundaries of an identified potential historic district.
Figure 1. Left: Location map of north Boulder showing 3139 7th St. within the Newlands neighborhood. Left:
Location of 3139 7th St. midblock between Evergreen Avenue and Forest Avenue facing east onto 7th Street.
BUILDING DESCRIPTION
The one-story house at 3139 7th St. was constructed in 1938. It is a vernacular L-gable frame
house with minimal ornamentation, typical of houses built during the years of the Great
Depression. The house has a moderately-pitched roof with no overhanging eaves; the front
porch provides the only detailing. The house was surveyed as part of the 1995 survey report of
1 “Application for Building Permit.” May 18, 1937. Planning and Development Services.
http://lfprod/WebLink/DocView.aspx?id=2427603&dbid=0&repo=LF8PROD
Item 5B - 3139 7th St LB memo 05.01.2024 Page 3 of 63
the Newland Addition and North Boulder. 2 See the 3139 7th St. historic building inventory
record (link).
Figure 2. 3139 7th St., east elevation facing 7th Street showing the façade including the entrance porch
with gable roof, 2024. Photo provided by applicant.
The east elevation (façade) includes a pair of vertically oriented double hung windows with six-
over-six divided lights. The windows appear to be original wood construction with aluminum
storm windows at the exterior. The offset porch includes a steeply pitched gable roof with
closed pediment finished with stucco. The square porch posts support a header that includes
a stucco detail and a curved front. The porch steps and floor are concrete. Metal railings have
been added to the flanking open sides of the porch and the stairs. The building is clad in drop
lap siding, with simple window trim and a concrete foundation.
2 Front Range Research Associates. “Boulder Survey of Historic Places: Newland Addition North Boulder.” June 1995. City of
Boulder.
Item 5B - 3139 7th St LB memo 05.01.2024 Page 4 of 63
Figure 3. 3139 7th St., north elevation, showing the stucco gable and divided-lite windows at the lower level, 2024.
Photo provided by applicant.
The north elevation includes a pair of vertically oriented double hung windows with divided
lights (six-over-six). The gable end is finished with stucco and includes a non-historic
horizontal sliding window.
Figure 4. 3139 7th St., west (rear) elevation, showing the addition of the Gable-L at the rear, roof dormer, and shed
roof porch, 2024. Photo provided by applicant.
A c. 1956 rear addition creates the current gable-L form. The main (original) roof includes a
skylight. The rear projection includes a shed roof dormer (see the south elevation) and an
almost square double-hung window in the gable end. The gable end at this elevation is clad in
Item 5B - 3139 7th St LB memo 05.01.2024 Page 5 of 63
horizontal siding (material unknown). A shed roof porch extends from the south corner of the
house. A vertically oriented double hung window is located under the shed roof.
Figure 5. 3139 7th St., south elevation, showing the stucco in the gable end and the divided lite windows below.
2024. Photo provided by applicant.
The south elevation mirrors the north elevation with a pair of vertically oriented double hung
windows with divided lights, and a stucco gable end that includes a non-historic horizontal
sliding window. The roof dormer at the L-gable addition is visible from this elevation and
includes a large window flanked with two smaller horizontal windows.
Figure 6. Garage at 3139 7th St., east elevation facing 7th Street (top left), north elevation (top, right), west
elevation facing the alley (below, left) and south elevation (below, right), 2024. Photos provided by applicant.
The garage is a simple one-story frame building with a metal roof and horizontal drop lap
siding. It includes outswing double garage doors on the elevation facing 7th Street and a single
Item 5B - 3139 7th St LB memo 05.01.2024 Page 6 of 63
fixed-pane divided light window on the north elevation. The building includes a corrugated
metal and frame shed roof addition on the south side that includes doors facing both 7th Street
and the alley, and transom vents on the south elevation.
Analysis of Integrity
Historic integrity is the ability of a property to convey its historical associations or attributes.
The National Park Service defines seven aspects of integrity to evaluate properties (location,
setting, design, materials, workmanship, feeling, and association). 3
Figure 7. Top left: 1938-1957 photograph of 3139 7th St. from Real Estate Appraisal Card (link). Top right: 3139 7th
St. historic building inventory record (link) photograph. Below: 3139 7th St. in 2024. Staff photograph.
3 U.S. Dept. of the Interior. “National Historic Landmarks Glossary of Terms.” National Park Service. Accessed November 2022. http
s://www.nps.gov/subjects/nationalhistoriclandmarks/glossary.htm
Item 5B - 3139 7th St LB memo 05.01.2024 Page 7 of 63
Figure 8. Left: The Real Estate Appraisal sketch from 1938-1956 shows the original 39 ft. by 25 ft. footprint with a
rear addition added c. 1949-1956. Right: the current footprint is unchanged from 1956. Not to Scale.
The house retains a high degree of architectural integrity since its construction 86 years ago.
Alterations include the construction of a rear addition in 1956 and shed-roof rear porch (date
unknown), addition of railings at the front porch, the addition of windows in the gable ends,
and the replacement of wood roof shakes with asphalt shingles.
The building is in its original location, and the original design remains largely intact at the
façade. The building retains its historic materials, including the drop siding, stucco in the
gable ends, and divided light windows. The building demonstrates the level of workmanship
common for the time period, and it conveys a feeling of its historic sense of the Great
Depression era. The association with its early residents is retained as is the setting of the
house on its property with walkways, lawn, and decorative plantings near the house.
PROPERTY HISTORY
Henry A. Drumm’s map 4 of the city of Boulder and vicinity from 1915 (Figure 10) shows the plat
of lots 34-35-36 in Block 29. The plats were recorded in 1891 by William Newland (see Area
History below). Land speculators purchased and sold large numbers of lots before houses
were built in the area. These investors included Elvira J. and Augustus W. Farnsworth, who
purchased 24 lots in Block 29 from A. D. McGlothlen in 1919. 5 They sold lots 34-35-36 (3139 7th
St.) to William Tippett in 1929.
4 Drumm, Henry A. “Drumm's wall map of the city of Boulder and vicinity.” 1915. Carnegie Library for Local History, Boulder.
https://localhistory.boulderlibrary.org/islandora/object/islandora%3A76609
5 Boulder County Records. https://boulder.co.publicsearch.us/doc/181366718
Item 5B - 3139 7th St LB memo 05.01.2024 Page 8 of 63
Figure 9. Lots 34-35-36 in Block 29 (which would become 3139 7th St.) shown on the 1915 Drumm map. Carnegie
Library for Local History.
William Tippett (1929 – 1932)
William Tippett purchased the land for $100 in March 1929.6 He sold the land in 1932. It is likely
that the Stock Market crash of October 1929 7 and subsequent Great Depression led to Tippett
selling the property.
R. F. Conrad (1932 – 1937)
R. F. Conrad purchased the property from William Tippett in 1932 for just $1.8 He held the
property for five years but didn’t build. Conrad sold the land to Fay and Clarence Heim for $10
in March 1937.9
Fay and Clarence C. Heim (1937 – 1942)
The Heims borrowed $1,200 from the Boulder Building and Loan Association to build the house
on the property.10 C. C. Heim is listed on the original building permit issued on May 18, 1937.
Before purchasing 3139 7th St., married couple Fay and Clarence Heim lived at 2695 5th St.11
Clarence Heim was a house painter and wall-paper hanger. He was born on October 6, 1895 12 in
6 Boulder County Records. https://boulder.co.publicsearch.us/doc/181461560
7 Richardson, Gary and Alejandro Komai, Michael Gou, and Daniel Park “Stock Market Crash of 1929.” Federal Reserve History.
https://www.federalreservehistory.org/essays/stock-market-crash-of-1929
8 Boulder Couty Records. https://boulder.co.publicsearch.us/doc/186007941
9 Boulder County Records. https://boulder.co.publicsearch.us/doc/181483476
10 Boulder County Records. https://boulder.co.publicsearch.us/doc/181501501
11 Boulder County Directory. 1936.
https://www.ancestry.com/imageviewer/collections/2469/images/13703933?usePUB=true&_phsrc=XFQ47&_phstart=successSo
urce&usePUBJs=true&pId=837385172
12 The National Archives At St. Louis; St. Louis, Missouri; World War II Draft Cards (Fourth Registration) For the State of Colorado;
Record Group Title: Records of the Selective Service System; Record Group Number: 147; Box or Roll Number: 059.
https://www.ancestry.com/discoveryui-content/view/17532146:1002
Item 5B - 3139 7th St LB memo 05.01.2024 Page 9 of 63
Illinois.13 Fay was born Fay Olive Dunn on May 21, 1903 in Oklahoma. She worked part-time as a
laundress while caring for their only child, Merlin. They lived in the house until 1942 when they
sold the property and moved to Eugene, Oregon.14
Louise G. and William G. Arnold (1942 – 1943)
William and Louise Arnold purchased the house in 1942 for $10.15 There is no indication that the
Arnolds lived in the house. William Finney rented the house in 1943.16
Doreane C. and Floyd L. Deisher (1943 – 1998)
The Deishers purchased the house less than a year later for $10.17
Floyd Leslie Deisher was born on November 29, 1912 in Lamar, Colorado.18 Doreane was born
Doreane Caroline Moore on December 30, 1918.19 They married on August 7, 1940.20 In 1950
Floyd worked as a machinist in an electric plant.21 Floyd and Doreane lived in the house with
their children, Carolyn (born 1941), Mary (born 1944, died in infancy), Michael (born 1945) and
Timothy (born 1956).22
Floyd died in 1976.23 Doreane continued to own the house until her death in 1997. Their
children sold the house in 1998.24
13 United States of America, Bureau of the Census. Sixteenth Census of the United States, 1940. Washington, D.C.: National
Archives and Records Administration, 1940. T627, 4,643 rolls. https://www.ancestry.com/discoveryui-content/view/40633075:2442
14 Department of Commerce. Bureau of the Census. 1913-1/1/1972. Population Schedules for the 1950 Census, 1950 - 1950.
Washington, DC: National Archives at Washington, DC. https://www.ancestry.com/discoveryui-content/view/24298513:62308
15 Boulder Couty Records. https://boulder.co.publicsearch.us/doc/186011547
16 Boulder City Directory. 1943. https://www.ancestry.com/imageviewer/collections/2469/images/14114669
17 Boulder County Records. https://boulder.co.publicsearch.us/doc/181607169
18 National Archives at St. Louis; St. Louis, Missouri; Wwii Draft Registration Cards For Colorado, 10/16/1940-03/31/1947; Record
Group: Records of the Selective Service System, 147; Box: 59. https://www.ancestry.com/discoveryui-content/view/5197678:2238
19 Find a Grave. Find a Grave®. http://www.findagrave.com/cgi-bin/fg.cgi.
20 Western States Marriage Index. Brigham Young University–Idaho.
http://abish.byui.edu/specialCollections/westernStates/search.cfm.
21 National Archives at Washington, DC; Washington, D.C.; Seventeenth Census of the United States, 1950; Year: 1950; Census
Place: Boulder, Boulder, Colorado; Roll: 3404; Page: 11; Enumeration District: 7-50. https://www.ancestry.com/discoveryui-
content/view/19369530:62308
22 Deisher family tree. https://www.ancestry.com/family-
tree/person/tree/168444106/person/242376039866/facts?_phsrc=XQN45&_phstart=successSource
23 U.S., Find a Grave® Index, 1600s-Current. http://www.findagrave.com/cgi-bin/fg.cgi.
24 Boulder County records. https://boulder.co.publicsearch.us/doc/184094719
Item 5B - 3139 7th St LB memo 05.01.2024 Page 10 of 63
Margaret J. Freund (1998 - present)
Margaret Freund purchased the property in 1998. Freund is the registered agent of 3139
Seventh Street LLC, which incorporated in 2018 and is the current owner.25
AREA HISTORY
The area around 3139 7th St. has seen significant transformations since the end of the 19th
century. This area is the ancestral homelands and unceded territory of Indigenous Peoples
who have traversed, lived in and stewarded lands in the Boulder Valley since time immemorial.
When gold was discovered in the mountains nearby, 60 original shareholders of Boulder City
Town Company ignored the 1851 Treaty of Fort Laramie, also known as the Horse Creek Treaty,
and claimed 1,280 acres alongside Boulder Creek on February 10th, 1859.26 In 1871, a town
government was organized under Boulder County regulations.
From the area survey: 27
In 1871, [William] Newland purchased his farm in North Boulder for $5,000.
In 1875, Newland experimented with the successful raising of spring wheat, but
discovered that dairy production and truck gardening were more profitable. By 1876,
Newland was growing one of the largest crops of strawberries in the Boulder area, with
eleven acres devoted to that fruit. Newland’s berries were marketed in Denver, as well
as in mining camps. In 1876, his fields produced an estimated six thousand quarts of
strawberries. Newland also grew grapes and apples. Like his neighbor Joseph Wolff,
Newland experimented with agricultural techniques. He was one of the first local
farmers to mix kerosene with water to kill grasshoppers.
Newland began to carve garden lots of small acreages from his farmland to sell to
others. … In 1891, the Newland Addition was platted, extending from Alpine to Grape
avenues between 2nd Street and Broadway
Although the Farmer’s Ditch flows through the Newland plat, the area is primarily irrigated by
Silver Lake Ditch, which was constructed in 1888. Many of the lots are sold with water rights to
Silver Lake Ditch. With access to irrigation, many of the owners planted orchards and truck
gardens and continued this usage until the beginning of the building boom after World War II.
25 Colorado Secretary of State.
https://www.coloradosos.gov/biz/BusinessEntityHistory.do?quitButtonDestination=BusinessEntityDetail&pi1=1&nameTyp=ENT&
masterFileId=20181349199&entityId2=20181349199&srchTyp=ENTITY
26 “Land Acknowledgement.” City of Boulder. https://bouldercolorado.gov/projects/land-acknowledgment
27 Front Range Research Associates. Ibid.
Item 5B - 3139 7th St LB memo 05.01.2024 Page 11 of 63
Figure 10. Left: Aerial view, 1938 28 with 3139 7th St. indicated. Right: approx. same area in 1958 29 showing the
increase in number of lots developed into housing during Boulder’s building boom after World War II.
Figure 11. Aerial view, 2023 with location of 3139 7th St. indicated. Google Earth.
PURPOSE AND CRITERIA FOR THE BOARD’S DECISION
Buildings proposed for demolition (as defined in Section 9-16-1, B.R.C. 1981) that are not
located in a historic district or designated as a landmark but are older than 50 years old are
reviewed pursuant to Section 9-11-23, B.R.C. 1981, using criteria defined by Section 9-11-1,
Purpose and Legislative Intent, and Section 9-11-2, City Council May Designate or Amend
Landmarks and Historic Districts. The Significance Criteria for Individual Landmarks (link) was
adopted by the Landmarks Board on Sept. 17, 1975.
28 United States Forest Service. Aerial Photographs of Colorado. Boulder. May 8, 1938. Photograph.
https://cudl.colorado.edu/luna/servlet/detail/UCBOULDERCB1~17~17~33264~118230
29 “North Boulder east of Broadway aerial photographs.” 1958. Carnegie Library for Local History, Boulder.
https://localhistory.boulderlibrary.org/islandora/object/islandora%3A40557
Item 5B - 3139 7th St LB memo 05.01.2024 Page 12 of 63
STAFF ANALYSIS
CRITERION 1: INDIVIDUAL LANDMARK ELIGIBILITY
The following is a result of staff’s research of the property relative to the Significance Criteria
for Individual Landmarks (link).
HISTORIC SIGNIFICANCE:
Summary: While the buildings at 3131 7th St. date from 1938 and were surveyed in 1995, staff does not
consider the property to possess a high degree of historic significance. The property was not a site of
a historic event that had an effect upon society, nor do the buildings show character, interest or
values as part of the development of the community, nor do they exemplify the cultural, political,
economic or social heritage of the community.
1.Date of Construction: 1938
Elaboration: Information based on Boulder County Tax Assessor records.
2.Association with Persons or Events: None
Elaboration: Fay and Clarence C. Heim constructed the house and lived there from 1937
until 1942. The Deisher family was the longest owners. Doreane C. and Floyd L. Deisher
purchased the house in 1943 and Doreane lived there until her death in 1997.
2.Distinction in the Development of the Community: Construction during the Great
Depression.
Elaboration: Throughout the early 20th Century, this area of Boulder was primarily
agricultural. The house was constructed during the Great Depression (1929-1941)30, during
a period of extreme economic hardship. It was one of the early houses constructed in the
area specifically as a residence and did not include agricultural land. The area became
primarily residential during the building boom after the Second World War.
3.Recognition by Authorities: Front Range Research Associates, Inc.,
Elaboration: The 3139 7th St. historic building inventory record (link) from 1995 notes that
the “house is representative of the vernacular frame dwellings erected in Boulder during
the period before World War II, as reflected in the minimal exterior ornament, the gabled
roof, the drop siding, and the gabled porch with squared column supports.”
ARCHITECTURAL SIGNIFICANCE:
Summary: The house and garage located at 3131 7th St. are representative vernacular residential
construction during the Great Depression, a period of severe economic hardship. While the
construction of any building during this period is interesting, the buildings do not have architectural
or aesthetic interest or value or provide significant examples of architectural styles of the past.
30 Richardson, Gary. “The Great Depression.” Federal Reserve History. https://www.federalreservehistory.org/essays/great-
depression
Item 5B - 3139 7th St LB memo 05.01.2024 Page 13 of 63
These buildings do not include innovative use of material or exemplary craftsmanship to be
considered significant.
1.Recognized Period or Style: Vernacular frame gable
Elaboration: The house is reflective of the type of construction during the Great
Depression, with basic construction and minimal ornamentation.
2.Architect or Builder of Prominence: None
3.Artistic Merit: Detailing around the front porch is interesting and shows skill.
4.Example of the Uncommon: Very few buildings were constructed during the Great
Depression, a period of extreme economic hardship.
5.Indigenous Qualities: None observed.
ENVIRONMENTAL SIGNIFICANCE:
Summary: The property located at 3131 7th St. does not have environmental significance. The
buildings do not represent a unique natural or man-made environment and the property is not
located within the boundaries of a potential historic district.
1.Site Characteristics: Residential Neighborhood
2.Compatibility with Site: The house retains its historic character, with a flagstone walk,
lawn and decorative plantings near the house.
3.Geographic Importance: The property is not located on a corner or prominently visible
within the neighborhood.
4.Environmental Appropriateness: None observed.
5.Area Integrity: Not located within a potential Historic District. The area’s open and
agricultural character from prior to World War II was replaced during a residential building
boom. Many of the area’s older structures have been altered to the point where historic
integrity no longer remains or they were demolished and replaced with larger, more
modern buildings.
CRITERION 2: RELATIONSHIP TO THE CHARACTER OF THE NEIGHBORHOOD
This property is an example of the gradual development of the Newlands residential
neighborhood that took place during the first half of the twentieth century. In the early
twentieth century, the area consisted primarily of farms, orchards, and ranches; by the 1940s,
residential development had begun in earnest. Many of the area residents worked as
carpenters, shopkeepers, and for companies such as the Mountain States and Telephone
Company. The area has changed dramatically from its pre-WWII rural character. This section of
7th St. retains a few houses from the first half of the twentieth century interspersed among
larger, more modern houses.
Item 5B - 3139 7th St LB memo 05.01.2024 Page 14 of 63
Figure 12. Left: Looking north from 3139 7th St. showing 3139 7th St. on the left and the other houses on the west
side of 7th Street. Right: looking north, showing 3139 7th St. on the right and the other houses on the west side of
7th Street. Staff photographs.
CRITERION 3: CONDITION OF THE BUILDING
The applicant owner has submitted information on the condition of the building. The
information is included in Attachment A: Applicant Materials and includes the following
statement: “The overall structural condition of the building is relatively poor, and appears to be
approaching the end of its serviceable life, without extensive intervention. Most of the
irregularities appeared to be a result of differential movement in between interior and exterior
foundations, and differential movement along perimeter foundation walls, hence the vertical
and inclined cracking in the unreinforced concrete foundation walls.”
CRITERION 4: PROJECTED COST OF RESTORATION OR REPAIR:
The applicant provided information regarding the projected cost of repair (see Attachment A),
which includes the following summary: “construction cost for the structural remediations
alone ranging from $250,000 to $350,000, plus $20,000 to $30,000 for the engineering itself. A
full estimate by the General Contractor, which includes the costs associated with required
repairs to the MEP systems and finishes in addition to the Structural fixes, anticipates total
remediation costs of $563,178.” This represents an estimated cost of restoration or repair of
$608/SF.
PUBLIC COMMENT
To date, staff has not received public comment regarding this application.
OPTIONS FOR THE BOARD’S DECISION
Pursuant to Section 9-11-23, B.R.C. 1981, if the Landmarks Board finds that the buildings
proposed for demolition may have significance under the criteria in subsection (f), the
application shall be suspended for a period not to exceed 180 days from the date it was
accepted by the city manager as complete, in order to provide the time necessary to consider
alternatives to the buildings’ demolition. If imposed, a 180-day stay period would start when
Item 5B - 3139 7th St LB memo 05.01.2024 Page 15 of 63
the completed application was accepted by the city manager (April 3, 2024 when the
Landmarks Board fee was paid) and expire on September 30, 2024.
If the Landmarks Board finds that the buildings to be demolished do not have significance
under the criteria set forth in section 9-11-23(f), B.R.C. 1981, the city manager shall issue a
demolition approval.
FINDINGS
Staff recommends that the Landmarks Board adopt the following findings:
A stay-of-demolition for the property at 3139 7th St. is not appropriate under the criteria set
forth in Section 9-11-23(f), B.R.C. 1981, in that:
1.While the house and garage are examples of residential buildings constructed during
the Great Depression, the property’s architectural significance is minimal, it does not
meet the significance criteria for individual landmark designation as is not associated
with persons or events significant to local, state or national history, nor does it have
environmental significance;
2.The character of the neighborhood has been diminished over time and the loss of its
buildings would not constitute a significant impact on Boulder’s historic resources;
3.It has been demonstrated to be economically challenging to rehabilitate the building.
ATTACHMENTS
A: Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 16 of 63
Page 1 of M
Updated 5<+3(+8 202N PPlanningg && Developmentt Servicess || 1MLLL8'6'.5++<+_
P.O. Box 791 Boulder, CO 80306 303-441-1880
boulderplandevelop.net
HIS -
Historic Preservation DemolitionReview Application
f REQUIRED MATERIALS FOR ALLAPPLICATIONS
Signed application
Site Plan (please show the footprint of the building(s), streets and alleys).85</*+'9 _
Current photographs of each side of the building, including the view from the street.85</*+'9 _
Side by side elevations of existing/proposed changes Ǝartial demolitions only.85</*+'9 _
f TO SUBMIT YOUR HISTORIC PRESERVATION DEMOLITION APPLICATION
x Email application to PDSskipatrip@bouldercolorado.gov. Put Historic Preservation in the subject line.
x Review fee will be invoiced to email address listed below. Log into Customer Self Service Portal (CSS) to pay.
x Questions? Reference the Demo Review FAQs or contact 303-441-1994 or historic@bouldercolorado.gov
x Si necesita ayuda para traducir esta información al español, llame al 303-441-1905.
f APPLICANT CONTACT INFORMATION
Name Phone#Email Address
Address City State Zip
f OWNER CONTACT INFORMATION SAME AS APPLICANT
Name Phone#Email Address
Address City State Zip
f PROJECT INFORMATION
Project Address: Number of Buildings
proposed for demolition:
Building Type and Date of Construction - Review is required
for buildings over 50 years old (check all that apply)
Scope of Work - Review is required when one or more of the following
is proposed (check all that apply):
Pre-1940 primary building (estimated date of
construction: )
Post-1940 primary building (estimated date of
construction: )
Accessory building(s) over 50 years old (estimated
date of construction: )
Full Demolition
On-Site Relocation
Off-Site Relocation
Removal of more than 50% of the roof
Removal of more than 50% of the exterior walls
Removal of any portion of a street-facing wall
Replacement of siding on a street-facing wall
Construction in front of a street-facing wall
Date:
PLAN
N/A
✔
✔
✔
Kyle Plantico 303.810.6292 kyle@rhaparch.com
1301 Walnut Street, Suite 101 Boulder CO 80302
3139 Seventh Street LLC 804.536.9800 mfreund@fultonhillproperties.com
PO Box 38542 Richmond VA 23231
Kyle Plantico Digitally signed by Kyle Plantico
DN: C=UM, E=kyle@rhaparchcom, O="RHAP
architecture + planning", CN=Kyle Plantico
Date: 2024.03.06 11:38:52-07'00'
3.6.2024
3139 7th Street 2 (Dwelling and Accessory Structure)
✔
1938
✔
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Existing Front (East) Elevation
Existing Side (North) Elevation
3139 7th Street - Existing Elevations
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Existing Side (South) Elevation
Existing Rear (West) Elevation
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Accessory Existing Front (East) Elevation
Accessory Existing Side (North) Elevation
3139 7th Street - Accessory Structure Existing Elevations
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Accessory Existing Side (South) Elevation
Accessory Existing Rear (West) Elevation
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Date: April 03, 2024
Project: HIS2024-00045
Regarding: Written Narrative Supporting Demolition of Structures at 3139 7th Street To: City of Boulder Landmarks Board
Marcy Gerwing, Principal Planner
Copy to: Margaret Freund, Owner
From: Kyle Plantico, RHAP Architecture + Planning in Collaboration with Dodd-Studio
examples of architectural styles of the past,” and is not intended "to preserve every old building in
the city.” (B.R.C. §9-11-1(a)&(b)). Though constructed in a “past era” the house was found to have no
association with significant persons, no association with significant events or patterns, and no
contribution to an Historic District by R.L. Simmons and J.E. Broeker in their 1995 Historic Building
Inventory Record, submitted as Exhibit B. Though inhabited by everyday Boulderites over the course
of its life, all undoubtedly with their own rich lives and stories, none have yet met the thresholds of
significance that would warrant landmark status or alternative preservation routes.
Similarly, the house does not provide a significant example of a past architectural style. In their
Inventory Record, Simmons and Broeker determined that the house “represents a type, period, or
method of construction,” and is “representative of the vernacular frame dwellings erected in
Boulder during the period before World War II.” The General Design Guidelines for Boulder's Historic
Districts and Individual Landmarks (the “Guidelines”) identify the vernacular wood frame as “by far
the most common style of architecture,” which “have been built throughout Colorado since 1860.
The Vernacular is an indigenous style generally constructed with locally available materials
according to traditional building practice. They are simple in form and detail and generally void of
ornamentation. These simple, modest homes are divided into four types according to floor plan and
roof shape: the Gabled “L”, the Front Gable, the Hipped Gable, and the Side Gable. These buildings
are wood frame construction and are usually sided with clapboard or wood shingles or a
combination of the two.” (Guidelines, pg. 14) Though the existing house and garage appear to meet
the definition of Vernacular Wood Frame under the Guidelines, the decades of alterations and
initial poor character of construction hardly qualify the structures as pristine examples of the
contextual Vernacular Wood Frame style in Boulder.
Expanding beyond the City’s Guidelines, R.W. Brunskill speaks of the vernacular as “...a building
designed by an amateur without any training in design; the individual will have been guided by a
series of conventions built up in his locality, paying little attention to what may be fashionable. The
function of the building would be the dominant factor, aesthetic considerations, though present to
some small degree, being quite minimal. Local materials would be used as a matter of course,
other materials being chosen and imported quite exceptionally.” (Illustrated Handbook of
Vernacular Architecture, pg. 27-28) Though local wood may have been used in the construction of
the house and garage, the structures otherwise do not make use of many of the materials and
conventions specific to Boulder. Where typical vernacular wood framed structures in Boulder often
utilize roof overhangs and wide, deep porches to shield their facades and important openings from
both the area’s heavy snowfall and harsh sun, these structures lack functional overhangs, and
make limited use of a narrow, shallow front porch stoop, exposing the exterior finishes and
fenestration to Boulder’s incredibly severe weather conditions. Views towards the Flatirons and
foothills, often the prize of similar structures in Boulder, and therefore a primary driver of many
vernacular designs, have little to no bearing on the placement and orientation of fenestration
throughout this house, though the presence of historic storm windows shows at least a limited
reaction to the local wind conditions. These structures lack identifying materials or conventions
that place them in Boulder, simply put, the house and garage would not be out of place in Denver, or
Topeka, or an East-coast suburb. Significant examples of the Boulder Vernacular Wood Frame
certainly exist, but these structures are not among them.
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2) The relationship of the building to the character of the neighborhood as an established
and definable area;
The house and garage not only lack identifying characteristics that place the structures in Boulder,
but they similarly lack any features that would identify them as part of the Newlands Neighborhood;
though the neighborhood itself defies definition by architectural style or general age of structures,
as it contains a multitude of each. The house and garage match the single-family nature of the
surrounding neighborhood but have no apparent historical significance or connection to the
establishment of the neighborhood.
3) The reasonable condition of the building; and
The original house, a simple wood-framed 25’ by 29’ main level with a side gable, small attic, and an
unfinished lower level was constructed in 1938. Per the Appraisal Card from the Carnegie Library
for Local History, submitted as Exhibit A, the character of construction was initially considered
“poor.” Sometime between 1938 and 1956, most likely 1949, a wood-framed detached single car
garage on a minimal foundation was constructed to the Southwest of the existing house. An 18’ by
11 1/2’ addition to the rear of the house was started prior to 1956, but formally permitted in June of
that year, which also appears to have formalized the attic as habitable area. When reappraised in
1949, it was indicated that the structure had already seen 12% physical depreciation, reflecting the
In the case of the garage, which was constructed on a substandard, shallow concrete foundation,
years of swelling and settling have caused not only significant damage to the concrete, but
introduced a Southward lean to the whole structure, which is visible to the naked eye, and
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Soilogic, Inc.
3050 67th Avenue, Suite 200 Greeley, CO 80634 (970) 535-6144
P.O. Box 1121 Hayden, CO 81639 (970) 276-2087
August 22, 2016
3139 7th Street LLC
c/o Fulton Hill Properties
1000 Carlisle Avenue, Suite 215
Richmond Virginia 23231
Attn: Ms. Margaret Freund
Re: Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street
Boulder, Colorado
Soilogic Project # 16-1176
Ms. Freund:
Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface
exploration you requested for the proposed single-family residence to be constructed at
3139 7th Street in Boulder, Colorado. The results of our subsurface exploration and
pertinent geotechnical engineering recommendations are included with this report.
We understand an existing residence and associated site improvements will be
demolished and removed from the property prior to construction of a new residence. The
existing residence consists of a single-story, wood-framed structure that we expect is
constructed over a crawlspace and that may contain a partial cellar area. We understand
the proposed new residence will be a single to two-story wood-frame structure
constructed over either a full basement or crawlspace. Foundation loads for the structure
are expected to be relatively light, with continuous wall loads less than 3.5 kips per lineal
foot and individual column loads less than 75 kips. Small grade changes are anticipated
to develop finish site grades in the residence area.
The purpose of our exploration was to describe the subsurface conditions encountered in
the completed site borings and develop the test data necessary to provide
recommendations concerning design and construction of the residence foundation and
support of floor slabs and exterior flatwork. The conclusions and recommendations
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
2
outlined in this report are based on results of the completed field and laboratory testing
and our experience with subsurface conditions in this area.
SITE DESCRIPTION
We expect the proposed residence will be constructed in the same general location as the
existing site residence located at 3139 7th Street in Boulder, Colorado. At the time of our
site exploration, an existing residence, concrete driveway and other associated exterior
flatwork and various landscape improvements were present on the property. The
building parcel was observed to be relatively level, with the maximum difference in
ground surface elevation across the new residence footprint estimated to be less than 2
feet.
EXPLORATION AND TESTING PROCEDURES
To develop subsurface information in the area of the proposed construction, one (1) soil
boring was extended to a depth of approximately 15 feet below present site grades as
close as possible to the new residence location as site access would allow. The boring
location was established in the field by Soilogic personnel based on the accessibility of
the site, discussion with the project architect and pacing and estimating angles and
distances from identifiable site references. A diagram indicating the approximate boring
location is included with this report. The boring location outlined on the attached
diagram should be considered accurate only to the degree implied by the methods to
make the field measurements. A graphic log of the auger boring is also included.
The test hole was advanced using 4-inch diameter, continuous-flight auger powered by a
truck-mounted CME-45 drill rig. Samples of the subsurface materials were obtained at
regular intervals using California barrel sampling procedures in general accordance with
ASTM specification D-1586. Penetration resistance measurements were obtained by
driving the standard sampling barrel into the substrata using a 140-pound hammer falling
a distance of 30 inches. The number of blows required to advance the sampler a distance
of 12 inches is recorded and helpful in estimating the consistency, relative density or
hardness of the soils/bedrock encountered. In the California barrel sampling procedure,
lesser disturbed samples are obtained in removable brass liners. Samples of the
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
3
subsurface materials obtained in the field were sealed and returned to the laboratory for
further evaluation, classification and testing.
The samples collected were tested in the laboratory to measure natural moisture content
and were visually classified in accordance with the Unified Soil Classification System
(USCS). The USCS group symbols are indicated on the attached boring logs. An outline
of the USCS classification system is included with this report. Classification of bedrock
was completed through visual and tactual observation of disturbed samples. Other
bedrock types could be revealed through petrographic analysis.
As part of the laboratory testing, a calibrated hand penetrometer (CHP) was used to
estimate the unconfined compressive strength of essentially cohesive specimens. The
CHP also provides a more reliable estimate of soil/bedrock consistency than tactual
observation alone. Dry density, Atterberg limits, -200 wash and swell/consolidation tests
were completed on selected samples to help establish specific soil/bedrock
characteristics. Atterberg limits tests are used to determine soil/bedrock plasticity. The
percent passing the #200 size sieve (-200 wash) test is used to determine the percentage
of fine-grained materials (clay and silt) in a sample. Swell/consolidation tests are
performed to evaluate soil/bedrock volume change potential with variation in moisture
content. The results of the completed laboratory tests are outlined on the attached boring
log and swell/consolidation test summaries.
SUBSURFACE CONDITIONS
The materials encountered in the completed site boring can be summarized as follows. A
thin mantle of vegetation and topsoil was encountered at the surface at the boring
location. The vegetative soil layer was underlain by brown lean clay with varying
amounts of sand. The lean clay was very stiff in terms of consistency, exhibited low
swell potential at in-situ moisture and density conditions and extended to a depth of
approximately 9 feet below grade, where it was underlain by grey/rust/olive/brown
claystone with interbedded siltstone/sandstone bedrock. The claystone with
siltstone/sandstone varied from firm to very hard in terms of relative hardness, exhibited
no/low to moderate swell potential at in-situ conditions and extended to the bottom of
boring B-1 at a depth of approximately 15 feet below grade.
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
4
The stratigraphy indicated on the included boring log represents the approximate location
of changes in soil/bedrock types. Actual changes may be more gradual than those
indicated.
Groundwater was not encountered in the completed site boring at the time of drilling and
the hole was backfilled upon completion of drilling due to safety concerns such that
subsequent groundwater level measurements could not be completed. Groundwater
levels will vary seasonally and over time based on weather conditions, site development,
irrigation practices and other hydrologic conditions. Perched and/or trapped groundwater
conditions may also be encountered at times throughout the year. Perched water is
commonly encountered in soils overlying less permeable soil layers and/or bedrock.
Trapped water is typically encountered within more permeable zones of layered soil and
bedrock systems. The location and amount of perched/trapped water can also vary over
time.
ANALYSIS AND RECOMMENDATIONS
General
The claystone bedrock encountered at this site exhibited variable swell potential (ranging
from no/low to moderate) at current moisture and density conditions. In addition,
claystone bedrock with high swell potential is known to be locally present. Heaving of
site improvements placed directly on or immediately above the expansive bedrock would
be expected as the moisture content of those materials increases subsequent to
construction.
In order to reduce the potential for movement of the residence in the expansive bedrock
environment if full basement construction is utilized, we recommend the structure be
supported by a drilled pier foundation system. This type of system extends the
foundation elements through expansive materials which are subjected to wetting and
swelling and can place them in materials not as likely to experience significant moisture
changes and resulting volume change. At the same time, drilled piers better concentrate
building dead-loads, aiding the resistance of uplift forces caused by expansive materials.
We note, however, that there will remain some risk associated with building in areas of
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
5
expansive bedrock. The risk of some movement and associated distress cannot be
eliminated.
If crawlspace construction will be completed, it is our opinion the residence could be
supported on conventional spread footing foundations provided a minimum separation
distance of three (3) feet can be maintained between foundation bearing elevation and the
bedrock surface. This would result in a maximum excavation/foundation bearing depth
of approximately six (6) feet below ground surface at the location of boring B-1
completed on this lot. We would be happy to provide recommendations concerning
spread footing foundation design for crawlspace construction should this construction
option be chosen.
Swell-consolidation tests indicate that the bedrock likely to influence basement slab-on-
grade construction possesses variable swell potential. Overall, we judge the bedrock to
possess moderate swell potential. For this site, we estimate total slab heave of 3 to 4
inches or more could be realized over time if deep wetting of the site occurs. Therefore,
we recommend all living area floors be constructed as structural floors supported
independent of the subgrade materials. Recommendations concerning drilled pier
foundation design criteria and structural floor systems are outlined below.
Demolition and Site Development
We understand the existing residence and associated site improvements will be razed
prior to construction of the new residence. Within the new residence and exterior
flatwork areas, all existing foundations, floor slabs and other site improvements should be
completely removed. Care will be needed to ensure all in-place fill/backfill materials
associated with the existing residence are also completely removed at this time. In
addition, all tree root systems and dry and desiccated soils associated with the tree root
systems should be completely removed from within the area of the proposed residence
and beneath exterior flatwork. The depth and extent of required removal can best be
established at the time of excavation through openhole observation. If/where required,
the excavated/removed materials should be replaced as controlled and compacted fill as
outlined below.
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
6
After stripping and completing all cuts and removal procedures, and prior to placement of
any new fill/backfill or flatwork concrete, we recommend the exposed subgrade soils be
scarified to a depth of 9 inches, adjusted in moisture content and compacted to at least
95% of the materials standard Proctor maximum dry density. The moisture content of the
scarified soils should be adjusted to be within the range of ±2% of standard Proctor
optimum moisture content at the time of compaction. If some backfilling of the existing
structure removal excavation is required, we recommend the excavation be continuously
benched during backfilling in order to reduce the potential for development of a shear
plane between the natural site soils and controlled backfill.
Fill and removal area backfill soils required to develop the site should consist of
approved, low-volume-change (LVC) soils free from organic matter, debris and other
objectionable materials. Based on results of the completed laboratory testing, it is our
opinion the natural site lean clay could be used as fill and backfill provided the proper
moisture content is developed in those materials at the time of placement and
compaction. Claystone bedrock should not be used as fill in structural areas of the site
due to its swell potential. If required, imported soils should consist of approved LVC and
relatively impervious soils free from organic matter and debris. If import is required, we
recommend an essentially-cohesive material be utilized in order to facilitate maintaining
a consistent upper shaft diameter in drilled pier excavations. Site fill and backfill should
contain a minimum of 25% fines in order to reduce the ability of those materials to pond
and transmit water. Suitable fill and backfill soils should be placed in loose lifts not to
exceed 9 inches thick, adjusted in moisture content and compacted as recommended for
the scarified soils above.
Care should be taken to avoid disturbing all subgrade soils prior to placement of any
overlying improvements. Soils which are allowed to dry out or become wet and softened
or disturbed by the construction activities should be removed and replaced or reworked in
place prior to concrete placement.
Drilled Pier Foundations
We recommend drilled pier foundations extend a minimum of 8 feet into competent
bedrock, with minimum shaft lengths of 22 feet and be designed using a maximum
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
7
allowable end bearing pressure of 30 kips per square foot (ksf). An allowable skin
friction value of 3,000 psf could be used for that portion of the pier extended into
competent bedrock. Credit for skin friction should be neglected for the top 3 feet of
bedrock penetration.
We recommend the drilled piers be designed to maintain a minimum dead-load pressure
of 10 ksf based on the cross-sectional area of the piers. If the minimum recommended
dead-load pressure cannot be achieved, increasing the minimum length and bedrock
penetration requirements outlined above could be considered to compensate for the
deficiency. An uplift skin friction resistance value of 2,000 psf could be used to calculate
additional uplift resistance for the increase in pier length only.
Piers should be designed with a length/diameter ratio of 30 or less, and full length steel
reinforcement to help transmit any axial tension loads that may develop in the pier shaft.
Uplift forces for use in reinforcing steel design can be calculated using the formula (Fup =
60 x D) where D is pier diameter in feet. A minimum 6-inch continuous void space
should be constructed beneath the foundation grade beams to concentrate dead-load on
the piers and allow for some movement of the subgrade soils to occur without
transmitting stresses to the overlying structure. Voids should be formed using approved
methods to prevent soil and debris from entering the void space. Void form material
should be collapsible enough such that sufficient loads cannot be transmitted through the
void form to mobilize the grade beams.
Based on the materials encountered in the completed site borings, we expect the pier
excavations could be completed using conventional auguring techniques. However, we
expect layers/zones of well-cemented bedrock will likely be encountered at the time of
caisson construction; therefore, specialized rock augers or core barrels may be required to
fully penetrate these materials. Pier excavations would be expected to remain stable for
short periods during construction such that we do not expect temporary casing of the
drilled shafts would be required. Groundwater was not encountered in the completed site
borings at the time of drilling. If rapid/excessive groundwater infiltration is encountered
at the time of caisson construction, temporary casing of the pier excavations may be
required to prevent water from entering the drilled shafts prior to concrete placement or a
tremmie used to place pier concrete. A maximum three (3) inch water depth is acceptable
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
8
at the bottom of pier excavations immediately prior to concrete placement. Free-fall
concrete placement is only acceptable if provisions are taken to avoid striking the
concrete on the sides of the caisson excavation or reinforcing steel.
Care will be needed to minimize the amount of sloughing/caving of the pier excavation
side walls. Sloughed soils will need to be removed from the bottom of the pier
excavations immediately prior to placement of reinforcing steel and pier concrete.
Pier concrete should have a slump in the range of 5 to 7 inches and be placed in the pier
excavations immediately after the completion of drilling, cleaning and placement of
reinforcing steel. Care should be taken in forming the upper edges of the pier excavation
to avoid "mushrooming" at the top of the drilled pier excavations. The mushroom shape
would provide additional area for expansive soil uplift forces. Cylindrical cardboard
forms or other approved means may be necessary to maintain a consistent upper shaft
diameter.
We estimate long term settlement of the drilled caisson foundations designed and
constructed as outlined above and resulting from the assumed structural loads would be
less than ¾ of an inch.
Living Area Floors
In order to help reduce the potential for movement of the residence floors, we
recommend all lower-level living area floors be constructed as structurally-supported
floors over a void space. Building codes should be followed for clear space requirements
below structurally supported floors with crawl space areas and will depend, in part, upon
the type of materials used to construct the floor, as well as the expansion potential of the
underlying soils/bedrock. Clear spaces for these types of floors normally range from 18
to 24 inches. A larger crawl space area has the advantage of allowing maintenance of
grade beam void spaces and sub floor utilities. Where other floor support systems and
materials are used, we recommend a minimum clear space/void of 8 inches be maintained
between the underside of the structural floor system and the surface of the subgrade/
exposed earth. It is prudent to maintain the minimum clear space/void below all
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
9
plumbing lines. This can be accomplished by hanging plumbing on the underside of the
structural floor between joists, or by trenching below the lines.
We recommend the subgrades in the voided/crawl space areas be sloped to drain to a
perimeter drain system in case of water infiltration into the crawl space/void areas. A
vapor barrier should be employed in the voided/crawl space areas in order to help
maintain in-situ subgrade moisture conditions and reduce the potential for migration of
soil moisture into the sub floor area. It may be prudent to consult with a specialist in
regard to mold prevention during design of the voided/crawl space areas of the residence.
Below-Grade Construction
We recommend a perimeter drain system be installed around the below-grade voided/
crawl space area to help reduce the potential for development of hydrostatic pressures
behind the below-grade walls and water infiltration into the voided/crawl space areas. A
perimeter drain system should consist of a four (4) inch diameter perforated drain pipe
surrounded by a minimum of six (6) inches of free-draining gravel. A filter fabric should
be considered around the free-draining gravel or perforated pipe to reduce the potential
for an influx of fine-grained soils into the system. The drain pipe should be placed at
approximate void space subgrade level around the interior perimeter of the structure with
a minimum slope of ⅛-inch per foot to facilitate efficient water removal and should be
designed to discharge to a sump pump and pit system.
Backfill placed adjacent to the foundation walls should consist of low-volume-change
(LVC) potential and relatively impervious soils free from organic matter, debris and other
objectionable materials. Based on results of the completed field and laboratory testing, it
is our opinion the overburden lean clay could be used as foundation wall backfill,
provided the proper moisture content is developed in those materials at the time of
placement and compaction. Claystone bedrock should not be used as backfill adjacent to
foundation walls due to its swell potential. The site lean clay and/or similar backfill soils
should be placed in loose lifts not to exceed 9 inches thick, adjusted to within ±2% of
standard Proctor optimum moisture content and compacted to at least 95% of the
materials standard Proctor maximum dry density.
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
10
Excessive lateral stresses can be imposed on the below-grade walls when using heavier
mechanical compaction equipment. We recommend compaction of unbalanced
foundation wall backfill be completed using light mechanical or hand compaction
equipment.
Lateral Earth Pressures
For design of below-grade walls where preventative measures have been taken to reduce
the potential for development of hydrostatic loads on the walls, we recommend using an
active equivalent fluid pressure value of 40 pounds per cubic foot. Some rotation of the
basement walls must occur to develop the active earth pressure state. That rotation can
result in cracking of the basement walls typically in between corners and other restrained
points. The amount of deflection of the top of the wall can be estimated at 0.5% times
the height of the wall. An equivalent fluid pressure value of 60 pounds per cubic foot
could be used for restrained conditions.
Variables that affect lateral earth pressures include but are not limited to the shrink/swell
potential of the backfill soils, backfill compaction and geometry, wetting of the backfill
soils, surcharge loads and point loads developed in the backfill materials. The
recommended equivalent fluid pressure values do not include a factor of safety or an
allowance for hydrostatic loads. Use of expansive soil backfill, excessive compaction of
the wall backfill or surcharge loads placed adjacent to the basement walls can add to the
lateral earth pressures causing the equivalent fluid pressure values used in design to be
exceeded.
At-Grade/Garage Floor Slabs and Exterior Flatwork
The garage and any other at-grade floor slabs and exterior flatwork could be supported on
reconditioned natural site soils and/or properly placed and compacted fill developed as
outlined in the “Demolition and Site Development” section of this report , provided a
minimum separation distance of three (3) feet can be maintained between finish floor slab
subgrade level and the bedrock surface.
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Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
11
Subgrade soils expected to receive flatwork concrete should be evaluated closely
immediately prior to concrete placement. If areas of disturbed, wet and softened, or dry
subgrade soils are encountered at that time, reworking of those materials or removal/
replacement procedures may be required.
The garage and any other at-grade floor slabs should designed and constructed as floating
slabs, separated from foundation walls, columns and plumbing and mechanical
penetrations by the use of block outs or appropriate isolation material. As a precaution,
we recommend the garage and any other at-grade floor slab partition walls be constructed
as floating walls to help reduce the potential for differential slab-to-foundation movement
causing distress in upper sections of the residence. A minimum 1½-inch void space is
recommended beneath all floating walls. Special attention to door framing, drywall
installation, stair systems and trim carpentry should be taken to isolate those elements
from the floor slabs, allowing for some differential floor slab to foundation movement to
occur without transmitting stresses to the overlying structure.
Depending on the type of floor covering and floor covering adhesive used in finished slab
on ground areas, a vapor barrier may be required immediately beneath the floor slabs in
order to maintain flooring product manufacturer warranties. A vapor barrier would help
reduce the transmission of moisture through the floor slabs. However, the unilateral
moisture release caused by placing concrete on an impermeable surface can increase slab
curl. The amount of slab curl can be reduced by careful selection of an appropriate
concrete mix. Slab curl cannot be eliminated. We recommend the owner, architect and
flooring contractor consider the performance of the slab in conjunction with the proposed
flooring products to help determine if a vapor barrier will be required and where best to
position the vapor barrier in relation to the floor slab. Additional guidance and
recommendations concerning slab-on-grade design can be found in American Concrete
Institute (ACI) section 302.
Exterior flatwork will experience some movement subsequent to construction as the
subgrade soils increase in moisture content. Based on results of the completed field and
laboratory testing, we expect the amount of movement of exterior flatwork supported on
reconditioned natural site soils and/or properly placed and compacted fill would be
limited. Care should be taken to ensure exterior flatwork is designed to provide positive
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 42 of 63
Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
12
drainage away from the residence and that positive drainage is maintained throughout the
life of the structure.
Drainage
Positive drainage is imperative for satisfactory long-term performance of the proposed
residence and associated site improvements. We recommend positive drainage be
developed away from the structure during construction and maintained throughout the
life of the site improvements, with twelve (12) inches of fall in the first 10 feet away from
the building. Shallower slopes could be considered in hardscape areas. In the event that
some settlement of the backfill soils occurs adjacent to the residence, the original grade
and associated positive drainage outlined above should be immediately restored.
Care should be taken in the planning of landscaping to avoid features which could result
in the fluctuation of the moisture content of the foundation bearing and/or flatwork
subgrade soils. We recommend watering systems be placed a minimum of 5 feet away
from the perimeter of the site structure and be designed to discharge away from all site
improvements. Gutter systems should be considered to help reduce the potential for
water ponding adjacent to the structure with the gutter downspouts, roof drains or
scuppers extended to discharge a minimum of 5 feet away from structural, flatwork and
pavement elements. Water which is allowed to pond adjacent to the site improvements
can result in unsatisfactory performance of those improvements over time.
GENERAL COMMENTS
This report was prepared based upon the data obtained from the completed exploration,
laboratory testing, engineering analysis and any other information discussed. The
completed boring provides an indication of subsurface conditions at the boring location
only. Variations in subsurface conditions can occur in relatively short distances away
from the boring. This report does not reflect any variations which may occur across the
site or away from the boring. If variations in the subsurface conditions anticipated
become evident, the geotechnical engineer should be notified immediately so that further
evaluation and supplemental recommendations can be provided.
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 43 of 63
Geotechnical Subsurface Exploration Report
Proposed Single-Family Residence (Lots 34-35-36, Block 29 Newlands)
3139 7th Street, Boulder, Colorado
Soilogic # 16-1175
13
The scope of services for this project does not include either specifically or by
implication any biological or environmental assessment of the site or identification or
prevention of pollutants or hazardous materials or conditions. Other studies should be
completed if concerns over the potential of such contamination or pollution exist.
The geotechnical engineer should be retained to review the plans and specifications so
that comments can be made regarding the interpretation and implementation of our
geotechnical recommendations in the design and specifications. The geotechnical
engineer should also be retained to provide testing and observation services during
construction to help determine that the design requirements are fulfilled.
This report has been prepared for the exclusive use of our client for specific application
to the project discussed and has been prepared in accordance with the generally accepted
standard of care for the profession. No warranties express or implied, are made. The
conclusions and recommendations contained in this report should not be considered valid
in the event that any changes in the nature, design or location of the project as outlined in
this report are planned, unless those changes are reviewed and the conclusions of this
report modified and verified in writing by the geotechnical engineer.
We appreciate the opportunity to be of service to you on this project. If we can be of
further service to you in any way or if you have any questions concerning the enclosed
information, please do not hesitate to contact us.
Very Truly Yours,
Soilogic, Inc. Reviewed by:
Wolf von Carlowitz, P.E. Darrel DiCarlo, P.E.
Principal Engineer Senior Project Engineer
36746 44271
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 44 of 63
Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 45 of 63
LOG OF BORING B-1
1/1 CME 45
4" CFA
Automatic
BMC
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N"MC DD qu % Swell @ Pressure # 200 Sieve
(ft)(%)(pcf)(psf)500 psf (psf)LL PI (%)
6" VEGETATION & TOPSOIL -
1
-
2
CL SANDY LEAN CLAY -
brown 3 CS 20 16.3 108.9 9000+0.4%----
very stiff -
4
-
5 CS 21 15.7 116.2 9000+0.5%-31 17 69.0%
-
6
-
7
-
8
-
9
-
10 CS 27 16.6 111.7 9000+None <500 ---
-
CLAYSTONE/SILTSTONE/SANDSTONE 11
grey/rust/olive/brown -
firm to very hard 12
-
13
-
14
-
15 CS 50/3 8.1 114.7 9000+2.5% @ 1k 4000 ---
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Surface Elev.-Field Personnel:3 Days After Drilling -USCSSamplerAtterberg Limits
Start Date 7/12/2016 Auger Type:During Drilling None
Finish Date 7/12/2016 Hammer Type:After Drilling None
3139 7TH STREET
BOULDER, COLORADO
Project # 16-1176
August 2016
Sheet Drilling Rig:Water Depth Information
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 46 of 63
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf)108.9
Final Moisture 17.8%
% Swell @ 500 psf 0.4%
Swell Pressure (psf)-
Sample ID: B-1 @ 2'
Sample Description: Brown Sandy Lean Clay (CL) with trace to minor Gravel
Initial Moisture 16.3%
3139 7TH STREET
BOULDER, COLORADO
Project # 16-1176
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 47 of 63
Liquid Limit 31
Plasticity Index 17
% Passing #200 69.0%
Dry Density (pcf)116.2
3139 7TH STREET
BOULDER, COLORADO
Project # 16-1176
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-1 @ 4'
Sample Description: Brown Sandy Lean Clay (CL) with trace to minor Gravel
Initial Moisture 15.7%
Final Moisture 17.4%
% Swell @ 500 psf 0.5%
Swell Pressure (psf)-
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 48 of 63
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf)111.7
Final Moisture 18.0%
% Swell @ 500 psf None
Swell Pressure (psf)<500
Sample ID: B-1 @ 9'
Sample Description: Beige/Brown/Rust Siltstone/Sandstone/Claystone
Initial Moisture 16.6%
3139 7TH STREET
BOULDER, COLORADO
Project # 16-1176
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 49 of 63
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf)114.7
3139 7TH STREET
BOULDER, COLORADO
Project # 16-1176
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-1 @ 14'
Sample Description: Beige/Brown/Rust Siltstone/Sandstone/Claystone
Initial Moisture 8.1%
Final Moisture 15.8%
% Swell @ 1000 psf 2.5%
Swell Pressure (psf)4,000
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 50 of 63
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification
Group
Symbol
Group NameB
Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF Clean Gravels
Less than 5% finesC Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravelF
Fines classify as ML or MH GM Silty gravelF,G, H
Coarse Grained Soils
More than 50% retained
on No. 200 sieve
Gravels
More than 50% of coarse
fraction retained on
No. 4 sieve Gravels with Fines More
than 12% finesC Fines classify as CL or CH GC Clayey gravelF,G,H
Cu ! 6 and 1 " Cc " 3E SW Well graded sandI Clean Sands
Less than 5% finesD Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sandI
Fines classify as ML or MH SM Silty sandG,H,I
Sands
50% or more of coarse
fraction passes
No. 4 sieve Sands with Fines
More than 12% finesD Fines classify as CL or CH SC Clayey sandG,H,I
PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M Silts and Clays
Liquid limit less than 50
Inorganic
PI < 4 or plots below “A” lineJ ML SiltK,L,M
Liquid limit - oven
dried
Organic clayK,L,M,N
Fine-Grained Soils
50% or more passes the
No. 200 sieve
Organic
Liquid limit - not
dried
< 0.75 OL
Organic siltK,L,M,O
Inorganic PI plots on or above “A” line CH Fat clayK,L,M
Silts and Clays
Liquid limit 50 or more PI plots below “A” line MH Elastic siltK,L,M
Liquid limit - oven dried Organic clayK,L,M,P Organic
Liquid limit - not dried
< 0.75 OH
Organic siltK,L,M,Q
Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-in. (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well graded
gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well graded
sand with silt, SW-SC well graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
F If soil contains ! 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
HIf fines are organic, add “with organic fines” to group name.
I If soil contains ! 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains ! 30% plus No. 200 predominantly sand, add
“sandy” to group name.
M If soil contains ! 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI ! 4 and plots on or above “A” line.
O PI < 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 51 of 63
GENERAL NOTES
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon - 1⅜" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger
ST: Thin-W alled Tube – 2.5" O.D., unless otherwise noted PA: Power Auger
RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger
CS: California Barrel - 1.92" I.D., 2.5" O.D., unless otherwise noted RB: Rock Bit
BS: Bulk Sample or Auger Sample W B: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch
penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For 2.5” O.D.
California Barrel samplers (CB) the penetration value is reported as the number of blows required to advance the sampler 12
inches using a 140-pound hammer falling 30 inches, reported as “blows per inch,” and is not considered equivalent to the
“Standard Penetration” or “N-value”.
WATER LEVEL MEASUREMENT SYMBOLS:
WL: W ater Level W S: While Sampling
WCI: W et Cave in W D: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB: After Boring ACR: After Casing Removal
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other
times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater.
In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils
have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand.
Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they
are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents
may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Relative
Density
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
< 3 0-2 Very Soft 0-5 < 3 Very Loose < 24 < 20 Weathered
3-5 3-4 Soft 6-14 4-9 Loose 24-35 20-29 Firm
6-10 5-8 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard
11-18 9-15 Stiff 47-79 30-50 Dense 61-96 50-79 Hard
19-36 16-30 Very Stiff > 79 > 50 Very Dense > 96 > 79 Very Hard
> 36 > 30 Hard
RELATIVE PROPORTIONS OF SAND AND
GRAVEL
GRAIN SIZE TERMINOLOGY
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Major Component
of Sample
Particle Size
Trace < 15 Boulders Over 12 in. (300mm)
W ith 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)
Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand
Silt or Clay
#4 to #200 sieve (4.75mm to 0.075mm)
Passing #200 Sieve (0.075mm)
RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Term Plasticity Index
Trace
W ith
Modifiers
< 5
5 – 12
> 12
Non-plastic
Low
Medium
High
0
1-10
11-30
30+
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 52 of 63
Date: 03 April 2024 To: Ms. Margaret Freund
3139 7th Street
Boulder, CO 80302
mfreund@fultonhillproperties.com Cc: Steven Dodd Dodd-Studio steve@dodd-studio.com Subject: 3139 7th Street, Boulder, Colorado Structural Condition Assessment Dear Ms. Freund: At your request, our representative visited the subject site at 3139 7th Street on March 29, 2024 accompanied by you, your architect Steve Dodd, and general contractor Rob Luckett and Paul Edwards.
The purpose of this visit was to perform a visual review of the existing structure and provide our
professional opinion of the overall structural condition of the structure. The existing structure at 3139 7th Street is a single-family 2-story residence with a partial shallow basement. It was built in 1938, and the front of the building faces east. The construction primarily
consists of wood framing for the roof, floor, and walls, cast-in-place board-formed concrete foundations,
presumably unreinforced and cast on continuous spread footings based on the age of the structure. At least one non-original addition was built on the back (west side) to the original 1938 residence at
unknown times, but we understand that all additions predated your ownership beginning around 1996. GEBAU Inc.
Consulting Structural Engineers
168 Centennial Parkway, Suite 180 · Louisville, Colorado 80027 · (303) 444-8545
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 53 of 63
April 3, 2024 3139 7th Street, Boulder, Colorado 2 Structural Condition Assessment Observations Notable structural abnormalities observed at the time of our visit include: 1. Visible Signs of Differential Foundation Movement: o Pervasive, recurrent cracking of interior wall surfaces on the main and upper-level interior walls, particularly around the level 1-2 staircase and opening from the front entry
into the kitchen.
o Hairline to moderate diagonal cracking emanating from various window head corners in exterior walls.
o Racked interior door frames variable width margins between doors and frames, non-latching door hardware, and separations between door casings and jambs. 2. Floor Framing Abnormalities: o The 2x8 joist-framed floors are significantly out of level.
o Ad-hoc supplemental floor beam and adjustable posts installed on basement slab.
o Disparate floor levels and retrofit raised thresholds are observed at transitions. 3. Foundation Wall Fractures: o Significant vertical fractures are observed in foundation wall elements, notably in the mechanical room retaining wall on the east end near the tee intersection, measuring in ~
½” width at top and ¼” width near bottom of the 3’+/- tall stem wall.
o Various vertical fractures in the exterior face of the concrete foundation wall above finished grade, some with sealant installed that has failed and exposed openings into
foundation walls above and below exterior grade.
o 4. Exterior, Site, Environmental, & Life-Safety Issues: o Flat or negative grading in exterior grade in the rear yard and exterior slabs
o Fractures in exterior slabs on grade.
o Efflorescence visible at the bottom of concrete foundation walls in the unfinished basement area.
o Non-conforming, narrow, and steep stairs (both stairs).
o Top surface fractures and doming in concrete basement floor slab.
o Large mature conifer tree very close to front (east) wall of house foundation. Discussion The overall structural condition of the building is relatively poor, and appears to be approaching the end of its serviceable life, without extensive intervention. Most of the irregularities appeared to be a result of
differential movement in between interior and exterior foundations, and differential movement along
perimeter foundation walls, hence the vertical and inclined cracking in the unreinforced concrete
foundation walls. Based on our experience with numerous projects in the direct vicinity, including the
new building directly to the south, and information contained in a current soils report for the subject
property, we understand the subgrade soil materials to be of moderate to highly expansive potential, likely
the root of the observed signs of movement. Permanent stabilization of existing perimeter and interior foundation elements would involve
comprehensive underpinning with deep foundations such as micropiles or helical piers, extending 20-30 ft
into bedrock, and excavating void space below existing footings. Interior slabs would need to be isolated
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 54 of 63
April 3, 2024 3139 7th Street, Boulder, Colorado 3 Structural Condition Assessment
from deep foundations, or be reestablished as reinforced structural slab on void, which would require excavating below existing foundation level in order to maintain the existing floor-ceiling clear height.
This would be problematic because the existing floor-ceiling height in the basement is non-conforming,
<7’, so the slab would seemingly need to be lowered. Interior column supports would need compatible
deep foundation piles with pile caps. Alternatively, the framed building structure could be shored and temporarily lifted to allow for removal
and replacement of the foundation with a reinforced concrete perimeter foundation wall on void and deep
piers, a new, lowered structural basement slab, waterproofing, drain system, vapor barrier, etc. to meet
current day building code. This would also likely trigger replacement of major HVAC and plumbing systems. Over spanned floor joists, in combination with active basement slab movement appear to be the cause of
ongoing cracking in interior wall finish surfaces. Previous efforts to stabilize the floor framing were only
partially effective at stiffening the floor system, but unsuccessful at releveling the floors to a serviceable
degree and are at the mercy of the basement floor slab instability. Existing main level joist remediation
would be most effectively accomplished with complete removal and replacement with an engineered floor
joist system. This could also help facilitate establishment of code-compliant stairs, provided the floorplan
can accommodate the additional space the stairs and floor openings would require. Efflorescence observed on the interior foundation wall surfaces indicates long-term moisture intrusion
from the subgrade. Presence of water being a common denominator, presence of efflorescence often
signals presence of mold. We recommend contacting an indoor air quality specialist for further
investigation and remediation plan recommendations as required. Overall, the effort to stabilize the existing structure to prevent or slow further deterioration and to extend
the building’s serviceable life-span will be significant proportionally costly. Recommendations In order to remediate the existing structure for purposes of continued occupancy and extended lifespan as-is, we recommend that you: 1. Excavate the entire building perimeter to bottom of existing footing elevation, install micropile or
steel helical piers and underpinning brackets at building corners & approximately 8ft oc. We
estimate approximately 25-30 piers will be required overall. 2. Clean exterior face of existing foundation walls, install crack sealant and reinforcement across
any significant fractures as required. 3. Install surface fluid-applied waterproofing, drainboard, perimeter drain pitched ¼”/ft to discharge
to daylight or sump pit with redundant pumps & backup power source. 4. Install micropile or helical pier with 12” diam x 30” reinforced concrete pier caps at interior
column supports. The count in item (1) includes interior piers. 5. Consider partial or complete foundation replacement as an alternative to remediation above. 6. Reframe existing main floor with 1.75” x 7.25” LVL joists @ 16”oc and re-sheathe with ¾” T&G
subflooring, normalizing the floor levels throughout the main level to eliminate raised
threshholds, trip hazards, and improve overall accessibility. 7. Replace basement-level bearing walls with new wood or steel beams and posts, founded on deep foundations. Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 55 of 63
April 3, 2024 3139 7th Street, Boulder, Colorado 4 Structural Condition Assessment 8. Consider renovating staircases to both level 2 and basement to correct the extreme steepness and
non-conforming riser heights and tread widths. 9. Comprehensively improve surface grading, drainage, downspout extensions discharging well
away from the structure. 10. Remove the mature evergreen adjacent the front foundation wall to prevent and reduce further
root damage to the foundation. 11. Replace fractured exterior flatwork that constitute trip hazards. Conclusions The remedial work necessary to restore the building to a fully safe and serviceable condition will be substantial. For the scope of repairs outlined above, we would estimate construction costs will be roughly
in the $250k-$350k range, not inclusive of refinishing, HVAC, MEP systems, public utilities, design fees,
or permitting. These improvements will be a significant step toward resembling a code-compliant
building, but unfortunately do not include aesthetic or architectural upgrades, and in fact could erode the
use of some of the spaces to accommodate increased areas allocated to stairs. Structural engineering
design fees for this general scope could range from $20k-$30k. We understand you are also considering demolishing the existing structure and building a replacement
house. We are not real-estate professionals nor financial professionals that can advise you on the cost-
benefit pieces of that decision. Still, we understand that the significant costs associated with making
necessary structural and serviceability improvements for the existing building to be occupied long term,
(particularly for any occupant with accessibility limitations), may be prohibitive or otherwise financially
unreasonable. If that is the case, then demolition and reconstruction is probably the best long-term solution. Thank you for contacting our office regarding this matter. Please feel free to call our office directly if you
have any questions. Sincerely, GEBAU, Inc. Joel Ambrosino, P.E. 04/03/2024
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 56 of 63
Item 3139 7th
Comments
4/3/2024
101 Printing $500.00
102 Soil Engineering Site Inspections $1,500.00 Open hole / pier observation if required / drain system inspections and reports
103 Structural Engineering Site Inspections $1,500.00 Anticipate additional site observations as foundation and structural elements are exposed
110 Builder's Risk Insurance $2,000.00 RLB estimate
120 Building Permit $7,500.00 Placeholder pending final scope of work
120 Sales/Use Tax $7,500.00 Placeholder pending final cost of work
124 Right of Way Permits and Traffic Control $2,500.00 Anticipate multiple street setups (example concrete pump truck)
150 Cleaning $1,000.00 Final clean of residence including windows
155 Trash Hauling/Recycling $2,000.00 Dumpsters as needed
160 Temporary Toilet $1,200.00 Rental for anticipated timeframe
161 Temporary Construction Fencing $1,500.00 Rental for anticipated timeframe
170 Construction and Punch List Labor $10,000.00
175 Tool Rental $1,000.00
190 Jobsite Supervision $26,400.00 Anticipate five month project
191 Project Management $10,000.00 Anticipate five month project
General Conditions Total $76,100.00
201 Mobilization and Site Management (BMPs)$5,000.00 BMP = "Best Management Practice" - Tracking pads, silt fence, sediment control, gravel, drainage etc
201 Excavation $12,500.00 Excavation around perimeter of residence for foundation work
202 Dirt Hauling $10,000.00 Exporting and importing of excavated dirt around perimeter of residence
206 Tree Removal and Site Clearing $7,500.00 Removal of trees, shrubs as required
220 Backfill and Compaction $7,500.00 Perimeter of residence for foundation work
230 Perimeter Drain $3,000.00 Full exterior perimeter drain system to sump pit
230 Sump Pump $2,500.00 Redundant sump pump with backup system
250 Utility Services $5,000.00 Budget for stabilizing all utility connections to home and minor repairs if needed due to construction
270 Grading $15,000.00 Regrade of property for proper drainage
Sitework Total $68,000.00
260 Driveway Removal and Replace $10,000.00 Driveway will be compromised during construction due to location and require replacement
266 Concrete Patios, Walkways and Steps $25,000.00 Patios. Walkways and steps will be compromised during construciton due to location and require replacement
Hardscape Total $35,000.00
275 Re-Landscape Allowance $50,000.00 Allowance for soft scaping and plantings around disturbed areas of property due to construction and regrading for proper drainage
Landscaping Total $50,000.00
301 Foundation Repair $15,000.00 Pending visual observation - initial budget for cleaning and sealing of cracks
302 Micro Pile Underpinning $108,500.00 Based on projected (31) micropiles and attachement with underpinning brackets
Foundation Repair Total $123,500.00
501 Structural Steel and Erection $7,500.00 Pending structural plans - anticipated work scope of main floor reframe, bearing wall in basement, stair renovation
3139 7th Street Estimate
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 57 of 63
Item 3139 7th
Comments
4/3/2024
Steel Total $7,500.00
610 Lumber and Supplies $25,000.00 Pending structural plans - anticipated work scope of main floor reframe, bearing wall in basement, stair renovation
620 Framing $35,000.00 Pending structural plans - anticipated work scope of main floor reframe, bearing wall in basement, stair renovation
650 Interior Trim Labor and Materials $15,000.00 Stair and rail renovation
Wood and Carpentry Total $75,000.00
701 Foundation Waterproofing $2,500.00 Spray applied waterproofing coating to existing foundation
701 Foundation Drainage Mat $5,000.00 Mechanically attached wall drain system
710 Gutters and Downspouts $1,000.00 Repair and adjustments as needed due to construction
751 Rigid Foundation Insulation $4,000.00 Insulation of foundation walls
Therma & Moisture Protection Total $10,000.00
901 Drywall $5,000.00 Budget placeholder for anticipated impact to drywall for structural repairs only
910 Painting $7,500.00 Budget placeholder for anticipated impact to painting for structural repairs only
951 Tile $5,000.00 Budget placeholder for anticipated impact to tile for structural repairs only
970 Hardwood Floors $5,000.00 Budget placeholder for anticipated impact to hardwood floors for structural repairs and stair renovation only
970 Carpet $5,000.00 Budget placeholder for anticipated impact to carpet for structural repairs and stair renovation only
Finish Repair Total $27,500.00
1501 Plumbing $5,000.00 Budget placeholder for anticipated impact to plumbing for structural repairs only
1550 HVAC $5,000.00 Budget placeholder for anticipated impact to HVAC for structural repairs only
Mechanical & Plumbing Total $10,000.00
1601 Electrical $5,000.00 Budget placeholder for anticipated impact to electrical for structural repairs only
Electrical Total $5,000.00
Hard Costs $487,600.00
Contingencies @ 5%$24,380.00
Total $511,980.00
190 Contractor Ovrhd/Profit $51,198.00
Total $563,178.00
Attachment A - Application Materials
Item 5B - 3139 7th St LB memo 05.01.2024 Page 58 of 63
Image 1:Vertical cracking & efflorescence in foundation wall.Image 2:Lower level slab cracking & efflorescence in foundation wall.Image 4:Mud jacks and support beams currently in place.Image 3:Mud jacks and support beams currently in place.Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 59 of 63
Image 5:Wall and ceiling cracking at window corner, indicative of settling.Image 6:Wall and ceiling cracking above window, indicative of settling.Image 8:Wall cracking, indicative of settling.Image 7:Ceiling cracking and structure telegraphing, indicative of settling.Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 60 of 63
Image 9:Noncompliant stair riser height.Image 10:Noncompliant stair tread depth.Image 12:Noncompliant stair riser height.Image 11:Noncompliant stair riser height.Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 61 of 63
Image 13:Noncompliant stair width.Image 14:Noncompliant upper level ceiling height.Image 16:Negative drainage towards house.Image 15:Leaning garage structure and cracked exterior concrete.Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 62 of 63
Image 17:Exterior foundation cracks, efflorescence & detaching entry stair.Image 18:Noncompliant concrete driveway.Attachment A - Application MaterialsItem 5B - 3139 7th St LB memo 05.01.2024Page 63 of 63