Alternate Design 2 Hr Fire Wall_SMS LetterStUdIOMENG
ARCHITECTURE
PLANNING
CONSULTING
STRAZZARA
November 21, 2019
Leif Bjorback
Building Official
City of Edmonds
Development Services Department
121 5th Ave N
Edmonds, WA 98020
23400 Highway 99 — 2 Hr. Fire Wall
Dear Mr. Bjorback:
The project at 23400 Highway 99 will require a 2-hour fire wall based on the IBC 506.2.3 allowable area
calculation for single -occupancy, multistory buildings. This calculation can be found in the building permit
resubmittal drawings on sheet G-002.
Fire walls are required to be continuous vertically (IBC 706.6) and shall be constructed of any approved
non-combustible materials (IBC 706.3). However, 706.3 also includes an exception that allows fire walls
within buildings of Type V construction to be of combustible materials. Also, fire walls shall be designed
and constructed to allow collapse of the structure on either side without collapse of the wall under fire
conditions (IBC 706.2).
Our concern with discontinuing the plywood sheathing at a 2-hour fire wall in Type VA wood frame
construction compromises the seismic integrity of the building and impacts the life -safety of its
occupants. We are proposing to continue the plywood sheathing through the fire wall at each level in
order to maintain structural continuity. A detail of the proposed floor condition at the 2-hour fire wall is
included in the plan resubmittal drawings (6/A804).
Attached you will find a letter from CKC Structural Engineers, the registered structural engineer for the
project, which lays out the structural concerns with discontinuing the plywood diaphragm in wood -frame
construction and provides justification that the intent of the fire protection code can still be met with the
proposed detail. Also attached is a Seismology Opinion Letter from the Structural Engineers Association
of Southern California (SeoSC) Light -Framing Construction Committee which supports our proposal.
TEL 206 587 3797 FAX 206 587 0588 2001 WESTERN AVE, SUITE 200 SEATTLE, WA, USA 98121 www.studioms.com
StUdIOMENG
STRA7ZARA
Respectfully,
Lucas Branham, AIA
Project Manager