HomeMy WebLinkAbout2021.11.03 23601 Golden Springs Dr Structural Review (Chiang).pdf
November 3, 2021
Via email: Jchiang@tresslerllp.com
Judy Y. Chiang, Partner
Tressler LLP
2 Park Plaza, Suite 1050
Irvine, California 92614
Regarding: 23601 Golden Springs Drive, Diamond Bar – Structural Review
ESE Job No. 21-L137
Dear Ms. Chiang:
At your request, I have reviewed two reports prepared by Khatri International, Inc. (Dilip Khatri, structural
engineer), dated April 26, 2017 and September 17, 2021, regarding the structural condition of 11 residential
buildings and 1 clubhouse at Diamond Bar Village. In addition to reviewing the reports, I made two site
visits to observe the physical condition of the buildings on October 25, 2021 and November 1, 2021.
The two Khatri reports (hereinafter 2017 Report and 2021 Report) detail numerous examples of deferred
maintenance such as termite damage, stucco damage, flaking paint, inadequate drainage, mold,
deteriorating roof framing, and foundation damage. The 2021 Report concludes that the “structural integrity
of the roof system is highly suspect on all 12 buildings.” Further, the report “red tagged” all buildings and
residential balconies, and it requires that residents vacate the Second Floor units and recommends vacating
the balconies. While allowing occupancy, the report also “yellow tagged” all First Floor residential units
pending temporary shoring of the Second Floor diaphragm and investigating the condition of wall framing.
On the basis of the 2021 Report, the City of Diamond Bar determined that the buildings were substandard
and issued an “Order to Vacate,” dated September 30, 2021, which states that the “building is immediately
dangerous to life, limb, property, or safety of the public.” In addition, the City of Diamond Bar formally red
tagged the Second Floor residential units, including the balconies, and the clubhouse, and formally yellow
tagged the First Floor residential units. The red tags prohibited entrance into the Second Floor units and
the clubhouse, and the yellow tagged residential units had access limited to property retrieval only.
PROFESSIONAL OPINIONS
Based upon my review of the two Khatri reports and my two site visits, I have formed the following
professional opinions:
1. The two Khatri reports generally describes with accuracy locations of termite damage and
environmental deterioration to the framing supporting the roofs over balconies. I concur that this
complex presents extensive examples of significant deferred maintenance; however, as discussed
below, I disagree with the life-safety significance of the observed conditions.
2. The 2021 Report concludes that “the structural integrity of the roof system is high suspect on all
12 buildings.” “Highly suspect” is an imprecise term but suggests that it is reasonable to believe
that the roof framing is incapable of functioning adequately to protect the life-safety of occupants.
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Tony Ghodsi, PE, SE
Lawrence Y. Ho, PE, SE
Michael K. Kawaharada, PE, SE
Christopher Rosien
Thomas A. Sabol, PhD, PE, SE
Russell Tanouye, PE, SE, LEED AP
Vladimir A. Volnyy, PE, SE
Ety Benichou, PE, SE
Mahmoud Faghihi, PE, SE
Zen Hoda, PE, SE
Kimberly Hoo, PE, SE
Diana Erickson Nishi, PE, SE
Reid Nishimura, PE, SE
Al Ikemura
Thomas Y. Nishi, PE, SE
Daniel Chan, PE, SE, LEED AP
Mohamed Hassan, PhD, PE, SE
Mitchel Le Heux, PE, SE
Katherlin Lee Choi
Milton S. Shiosaki
Daniel W. Shubin
Edward Silver, PE, SE
Kimberly F. Tanouye
Judy Y. Chiang
Tresller, LLP
Re: 23601 Golden Springs Drive, Diamond Bar
November 3, 2021
Page 2 of 3
The report equates the “red tag” rating to “high risk,” which was assigned to all Second Floor
residential units, balconies, and the clubhouse. In the context of “highly suspect,” the report appears
to suggest that imminent threats to life safety exist. The City of Diamond Bar appears to have come
to such an interpretation of the 2021 Report because they issued an Order to Vacate. I disagree with
this interpretation.
a. The roof framing in the complex generally consists of two different types: flat roof framing
over the vast majority of the residential units and sloped framing supporting tile roofs over
the balconies and most of the clubhouse. The Khatri reports fail to note this distinction. All
examples of roof damage cited in the report are limited to the sloped roof framing over the
balconies. No damage has been reported to the flat roof framing that is directly over
the living spaces.
b. Various levels of damage or deterioration of exposed sloped roof framing are obvious from
a visit to the site; however, even in the case where an edge beam has completely
deteriorated, the roof in this area has not collapsed. Wood beams with significant apparent
damage rest upon wood framed walls and the roof has not collapsed. While I do not
recommend that these conditions remain indefinitely, alternative load paths exist to
temporarily support the roof in the areas of the most significant damage. These portions of
the roof should not be stood upon, and prompt repair is necessary, but collapse is not
imminent.
c. In areas of sloped roof framing where limited or no damage is observed, the 2021 Khatri
Report nevertheless recommends vacating the associated Second Floor residential units
and balconies. Further, it suggests that the First Floor units should also be vacated, although
the language in the report addressing this point is garbled. I disagree that any of the
residential units must be vacated.
3. The two reports identify examples of stucco damage. The examples appear to reflect minor cracking
due to normal wear and tear as well as failed stucco patches performed prior to finishing or repainting
the stucco. The deteriorated stucco does not represent an imminent life-safety hazard.
4. Other examples of stucco damage cited in the 2021 Report appear to be intentional exposures
documented in the 2017 Report (e.g., missing, rectangular patches of stucco sawcut to expose
underlying framing). Some of these exposures have been left unrepaired. While these localized
exposures should be repaired to prevent continuing damage to underly framing, I do not believe that
these conditions represent an imminent life-safety hazard.
5. I found little to no evidence of significant foundation damage due to foundation uplift, which the 2021
Report describes as “extensive.” I disagree with this characterization based on the lack of collateral
damage to building finishes that would signify significant differential movement of the foundation. It is
my opinion that any foundation movement that has occurred is structurally insignificant and
does not represent an imminent life-safety hazard.
6. My overall conclusion is that the damage observed throughout the complex does not rise to the level
where it poses an imminent threat to life-safety. Repair of the damage in a timely manner is required
to prevent additional deterioration, which could eventually lead to a life-safety hazard, but this work
Judy Y. Chiang
Tresller, LLP
Re: 23601 Golden Springs Drive, Diamond Bar
November 3, 2021
Page 3 of 3
need not be completed immediately. Given the preliminary nature of this review, I have not determined
a timeframe under which the repairs must be completed.
Recommendations
1. I recommend that the City of Diamond Bar remove the red and yellow tags from the residential units
and the clubhouse.
2. Given the amount of observed damage to the roof framing over the balconies in a limited number of
units (Units D8, F6, E8, B8, H7 and H8), I recommend that access to the balconies and the porch
area below them be restricted until adequate temporary shoring is installed or the framing is repaired.
I based these recommendations on the presence of significant damage to the beam supporting the
roof rafters, rather than the presence of damage to the rafters or sheathing, even if extensive, because
there isn’t an obvious alternative load path should the beams fail. The roof rafters, on the other hand,
are supported by beams or walls.
3. I recommend preparation of a comprehensive plan to identify areas requiring repair to restore the
condition of the original roof framing over the balconies, the exposures in the exterior skin of the
building, and unprotected, stucco covered parapet conditions. As appropriate, additional exposures
may be required to assess the condition of framing obscured by exterior finishes. The plan should
identify levels of repair priority and a completion schedule for each level approved by the City of
Diamond Bar.
4. Stairs leading to two Second Floor units (Units C6 and K8) have been shored temporarily. I
recommend that the shoring be adequately attached to the slab-on-grade and to the stair framing,
and that an assessment be undertaken to determine the reason for the shoring and a method to
address any underlying structural issues. Based on the assessment, I recommend preparation of a
plan to repair these stairs with a completion schedule approved by the City of Diamond Bar.
5. Loose tile was observed on the sloping roof over the balcony of Unit E6, which should be removed or
reattached as soon as possible.
I have not addressed the significance of the presence of mold, the ongoing presence of termites, or other areas
that are not structural in nature.
Please contact me if you should have any questions.
Sincerely,
Thomas A. Sabol, PhD, SE
Principal
TAS:klc