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EdXing-cont insul full
Date: August 30, 2022 Leonid Glavatskiy LZG Construction LLC 2402 S 312th Street Federal Way, WA 98003 RE: Edmonds Crossing Apartments 23830 Edmonds Way Edmonds, WA 98026 Leonid, You have requested to revise the design of the exterior wall to delete the air space and the rigid insulation. The attached drawing CA2.0, dated 8/30/22, shows an alternative design for Exterior Wall System 1 that removes the exterior insulation and adds spray foam insulation within the wall cavity. As a 3-story multifamily housing structure, this project is governed by the Washington State Energy Code Residential Provisions. Table R402.1.1 of that Code requires a minimum R-value of 21 for a wood framed exterior wall in this climate zone. The revised design for the Exterior Wall System 1 provides an insulation R-value of 28 (see attached Insulation Certificate), which meets that prescriptive requirement. Note that, for this wall system to be compliant with the Code, it is necessary to install insulation with an R-value of 10 at all headers. This requirement can be met with 2" of rigid foam insulation. The revisions to Exterior Wall System 1 can also be applied to Exterior Wall System 2. The only difference with that wall system is the change of the exterior facing from cement board siding to cement board panels. Please let me know if you have any questions or if you need any further clarification about the consequences of this revision. Sincerely, Haynes Lund AIA, LEED©AP Haynes Wilson Lund Architects LLC 385 101s, Avenue SE Bellevue, WA 98004 30 August 2022 Haynes Wilson Lund Architects LLC page 1 OUTSIDE AIR FILM (R-0.17) -- CEMENT BD LAP SIDING (R-0.34) -- AIR -WATER BARRIER -- 15/32" PLYWOOD SHEATHING (R-0.63) - 2x6 WOOD STUDS, SEE STRUCT FOR SPACING -- 2" SPRAY FOAM INSULATION (R-15) - 3-1/2" BATT INSULATION (R-13) - 5/8" GYPSUM BOARD (R-0.45) INTERIOR AIR FILM (R-0.68) TOTAL R-VALUE = 30.27 EXTERIOR WALL SYSTEM 3„ = 1,_O„ FIRE RATING = 0 HOURS U- VALUE = 0.03303 PER CALCULATION STC RATING = NOT RELEVANT R N K EASTS I D E L LC EDMONDS CROSSING APARTMENTS 23830 EDMONDS WAY EDMONDS, WA 98026 30 AUG 2022 CA2.0 Western Insulation Services Inc. 17969 W Spring Lake DR SE Renton WA 98058 253-486-6585 Certificate of Insulation Contractor: LZG Construction Job Address: 23830 Edmonds Way Edmonds WA Product R-Value Location SWD urethane R-15 2" ave spray foam exterior walls Fiber glass R-13 exterior walls Total R-28 exterior walls Authorized Agent: 1 � " 11LA � Date � �� ` -�