The URL can be used to link to this page

REVIEWED RESUB 1 BLD2022-1340+Structural__Calculations+11.4.2022_12.01.14_PM+3203871STRUCTURAL BASIS OF DESIGN PROJECT DESCRIPTION The project consists of an interior remodel of the main floor of a single family home in Edmonds, Washington. The structure is a single story home with a daylight basement. The footprint of the home is approximately 2,600 square feet. The existing structure is light framed wood construction with prefabricated truss at the roof. The existing lateral system consists of OSB sheathed wood shear walls. The majority of the existing structure will be exposed during construction, as this is a "full gut" remodel. DESIGN STANDARDS In accordance with City of Edmonds, the following design standards are utilized for the structural analysis and design: 1. International Building Code (IBC) 2018 2. International Residential Code (IRC) 2018 3. American Society of Civil Engineers (ASCE) 7-16 4. American Wood Council National Design Specification (AWC NDS) 2018 5. American Wood Council Special Design Provisions for Wind & Seismic (AWC SDPWS) 2015 STRUCTURAL MODIFICATIONS Structural modifications for the project are limited to the southeast corner of the main floor, where an existing exterior balcony will be enclosed to increase the square footage of the primary bedroom. The structural modifications include: WINDOW HEADER MODIFICATIONS The window configuration will be modified at the primary bedroom and associated bathroom, requiring modifications to the window headers. Per conversation with the contractor, existing headers will be salvaged and reused at the new locations. The header modifications are as follows: At the east wall of the bedroom, three new windows will be added and two existing windows will be infilled. New headers will be provided at the new windows on this wall. • At the south wall of the bedroom, two new windows will be added. These windows will be located beneath an existing header beam. This existing header beam is currently supporting the roof trusses at the existing balcony. The addition of the windows below this header does not affect this header beam design. • At the south wall of the bathroom, an existing window is being enlarged. A new header will be provided at this window. Resizing of windows occurs at other locations on the main floor (kitchen and dining room). However, at these locations, window rough opening widths will not be increased, therefore existing headers are not affected. SHEAR WALL MODIFICATIONS To accommodate the window reconfiguration, existing shear walls will be modified at the east wall of the primary bedroom and at the south wall of the associated bathroom. Portions of these existing shear walls will be removed to allow for installation of the new windows, and new sections of shear wall will be provided where existing windows are to be infilled. New shear wall segments will be sheathed with APA rated structural plywood. Nailing at the new sheathing will be similar to the existing shear wall construction, to ensure similar rigidity and proper load sharing occurs between new and existing shear walls. All infill wall framing will be 2x6 construction, with studs at 16" on -center. REFERENCE DRAWINGS The structural analysis and design is based on the remodel drawings provided by MStudios, dated 9/29/2022, as well as original structural drawings dated 7/24/2000. The original structural drawings indicate that the structure was designed to the requirements of UBC 97 2 The images below show the existing structure at the main floor and roof, per the available original structural drawings. MAIN FLOOR PLAN ve_— As -Built - Main Floor Plan ��■Mil - o■■■� �mool .�Ml mma I■ I■ IN 1.11 .l NOR � O IN IN �I■ IN ■I Ell ROOF PLAN v++•-r-o• As -Built - Roof Plan The image below shows the project intent at the main floor, per the provided remodel drawings. r • r • i .I • f. • -r rAh6- AID Remodel - Main Floor Level N 5 DESIGN CRITERIA The following gravity and seismic loading is used for the project: GRAVITY LOADING Live Load Roof Live 20 psf Snow Load 25 psf (Non -reducible) Dead Load Roof Asphalt Shingles 3 psf Plywood Sheathing 2 psf Trusses 3 psf Gypsum Ceiling 3 psf Insulation & Misc 5 psf Roof DL Sum 16 psf Ext Walls Cedar Siding 2 psf Plywood Sheathing 2 psf 2x6 Wall Framing 2 psf Gypsum 1 psf Insulation & Misc 5 psf Wall DL Sum 12 psf Int Walls 2x4 Wall Framing 1.5 psf Gypsum - 2 sides 2 psf Insulation & Misc 5 psf Wall DL Sum 8.5 psf 6 SEISMIC LOADING Lateral System: Light -frame (wood) walls sheathed with wood structural panels rated for shear resistance R = 6.5 Risk Category II Ie = 1.0 Seismic Design Category = D1 (per City of Edmonds for residential) Per ASCE 7 Online Hazard Tool SS = 1.277 Fa = 1.2 SMs = 1.532 SDS = 1.022 S1 = 0.448 F, = 1.5 SM1 = 0.672 SD1 = 0.448 Seismic Base Shear V = CSW = 11,167 lbs — CS = SDAR/ld = 1.022/(6.5/1.0) = 0.157 (Governs) Cs, max = SD1/T(R/Id = 0.448/0.152(6.5/1.0) = 0.453 max --+T=Cthnx=0.02x15°'75=0.152s Cs,min = 0.044SDSIe = 0.044(1.022)(1.0) = 0.045 min — W = Wroof + Wextwalls+ Wint walls = 71,130 lbs Wroof =16psf x 2600sf = 41,600 lbs Wext walls =12psf x 8' x 2351f = 22,560 lbs Wint walls = 8.5psf x 8'/2 x 2051f = 6,970 lbs v = VIA = 11,1671bs/2600sf = 4.3 psf p = 1.3 for SDC D pv = 5.6 psf For ASD: 0.7xpv = 3.9 ps (ASCE 7-1612.8-1) (ASCE 7-1612.8-3) (ASCE 7-1612.8-7) (ASCE 7-1612.8-5) 7 SHEAR WALL DESIGN New shear walls at the east primary bedroom walls will consist of sheathing and nailing to match the existing shear walls. The image below shows the shear wall schedule per the available original structural drawings. 1 1 :S # eed ad AiVic. N M :l TIC GilMv iUf1 HOL C MF N1.`I PNC�K3RA{it ANCF1Ofx BOLTS hM d� �■ 1 LOMM hoWWR W each end ErMi�+ E. Aeid FDN Dow is aqm Err nwewe "i I V, ex„leMl.rk J 1 w.m o.,wAa Vw rams n SW vW-v 4 Tlruw*d rW 1 aouplw as rM's SHEET NA1U44 914ALL NOT PENE1VATE PAST FLUSH WITH IHt 3liH11'AUt, A STREMGTH REELCT0M OF 50 0WI RS AW RE44AR PC IS NOT ALLOWED* THE fir$11L11W4 SPACE aS LESs MAN QH Lulu ru e. Per AWC SDPWS, the rated shear capacity of the existing shear walls is 255 plf (ASD). 8 HEADER DESIGN Existing headers will be salvaged and reused at new locations in the primary bedroom and associated bathroom. The image below shows the structural properties of the header beams per the available original structural drawings. LUMBER MENGTH. PER 1997 UBC & 1994 N.D.S. STANDARDS HEM RR FOR 2x MEMBERS, DOUG FIR FOR K0S & HEAMRS U.N.O. ,Q1 2x H A TERS ��— B AFC CITY 5 1.3 x OF 0 1000 95 13 BEAMS k HEADERS 4x DF f2 575 95 1.6 4x OF #1 1000 85 1.7 6x DF #2 S75 1.3 5-X DF#1 1350 85 1,& OF/LARCH 16F—V3 DF/QF; 1600 165 1_U5 LARCH 24F--V4 DFF fDF� 24,D0 165 1.a TILEVER D �LIJ—LAM -InLRS 24F—U$ D/F D/F GLU—LAi4 EIVIS TO BE KILN DRIES D.F. DISFL. Y AITC STAMP. ALL STRUCTURAL HEDGERS TO BE #2 HEM/FIR CND BETTER A NOTED ON PLAK These properties will be used in the design of the headers. 9 H .� 0 eet�i t ` 2 -Cu < < Ts o t . ' 0VKAl14&Jt- Pi Des � ^� t 5 rV4 O 541-5 wl" ?!C, D 97V lb co 1.0 vi 1 1) TR 1-5 & zId 11066 >10 z.rs oo —, TVA DM 4-7-4- (1�+25-)4. z °4,t ,�lZ 6 ►n Q