WSR 18-21-130
EXPEDITED RULES
BUILDING CODE COUNCIL
[Filed October 18, 2018, 4:16 p.m.]
Title of Rule and Other Identifying Information: Chapter 51-51 WAC, Washington state amendments to the 2015 International Residential Code.
Purpose of the Proposal and Its Anticipated Effects, Including Any Changes in Existing Rules: The proposed rule adds an alternate method for sizing footings for light-framed residential construction.
Reasons Supporting Proposal: The proposed rule provides additional paths for prescriptively sizing footings based on accepted engineering practices.
Statutory Authority for Adoption: RCW 19.27.031, 19.27.074.
Statute Being Implemented: Chapter 19.27 RCW.
Rule is not necessitated by federal law, federal or state court decision.
Name of Proponent: Washington state building code council, governmental.
Name of Agency Personnel Responsible for Drafting and Implementation: Richard Brown, 1500 Jefferson Street S.E., Olympia, WA, 360-407-9277; and Enforcement: Local jurisdictions.
This notice meets the following criteria to use the expedited adoption process for these rules:
Corrects typographical errors, make address or name changes, or clarify language of a rule without changing its effect.
Have been the subject of negotiated rule making, pilot rule making, or some other process that involved substantial participation by interested parties before the development of the proposed rule.
NOTICE
THIS RULE IS BEING PROPOSED UNDER AN EXPEDITED RULE-MAKING PROCESS THAT WILL ELIMINATE THE NEED FOR THE AGENCY TO HOLD PUBLIC HEARINGS, PREPARE A SMALL BUSINESS ECONOMIC IMPACT STATEMENT, OR PROVIDE RESPONSES TO THE CRITERIA FOR A SIGNIFICANT LEGISLATIVE RULE. IF YOU OBJECT TO THIS USE OF THE EXPEDITED RULE-MAKING PROCESS, YOU MUST EXPRESS YOUR OBJECTIONS IN WRITING AND THEY MUST BE SENT TO Richard Brown, Washington State Building Code Council, P.O. Box 41449, phone 360-407-9277, email sbcc@des.wa.gov, AND RECEIVED BY December 28, 2018.
October 11, 2018
Doug Orth
Council Chair
AMENDATORY SECTION(Amending WSR 16-03-025, filed 1/11/16, effective 7/1/16)
WAC 51-51-0403((Reserved.))Section R403—Footings.
R403.1.1 Minimum size. The minimum width, W, and thickness, T, for concrete footings shall be in accordance with Tables R403 1(1) through R403.1(3) and Figure R403.1(1) or R403.1.3, as applicable. The footing width shall be based on the load-bearing value of the soil in accordance with Table R401.4.1. Footing projections, P, shall be not less than 2 inches (51 mm) and shall not exceed the thickness of the footing. Footing thickness and projection for fireplaces shall be in accordance with Section R1001. The size of footings supporting piers and columns shall be based on the tributary load and allowable soil pressure in accordance with Table R401.4.1. Footings for wood foundations shall be in accordance with the details set forth in Section R403.2, and Figures R403.1(2) and R403.1(3).
EXCEPTION:
Light-frame construction shall be permitted to have minimum footing size in accordance with Figures R403.1.1(1) through R403.1.1(4) in lieu of that determined by Table R403.1(1).
Figure R403.1.1(1)
Alternative Minimum Footing Size for Light-Frame Construction a,b,c,d,e,f,g,h,i
20 PSF Snow Load
Notes:
a
The minimum footing size is based on the following assumptions: Material weights per Section R301.2.2.2.1 and soil density = 120 pcf. Wood framed walls = 10 foot; crawlspace stem wall = 6 inches × 36 inches; basement wall = 8 inches × 120 inches. Total load (TL) equal to the maximum of three load combinations: LC1=D+L, LC2=D+S and LC3=D=0.75(L+S), where D=dead load, L=live load, S=snow load. TL=max (LC1, LC2, LC3).
 
b
Use tributary span of floor and roof. Figure may be used to size exterior and interior footings.
 
c
Add 4 feet to tributary floor span for each wood framed wall above first level (i.e., 4' for 2-story, 8' for 3-story).
 
d
Multiply floor span by 1.25 for interior footings supporting continuous joists.
 
e
Multiply footing width by (1500 psf/capacity) for soil capacity other than 1500 psf. See Section R403.1.1 for thickness.
 
f
Dashed line may be used for interior footing size only.
 
g
Use footing size indicated on line above the span combination used.
 
h
For span combinations above the upper line, a design professional is required.
 
i
Interpolation between footing sizes is allowed. Extrapolation is not allowed.
Figure R403.1.1(2)
Alternative Minimum Footing Size for Light-Frame Construction a,b,c,d,e,f,g,h,i
30 PSF Snow Load
Notes:
a
The minimum footing size is based on the following assumptions: Material weights per Section R301.2.2.2.1 and soil density = 120 pcf. Wood framed walls = 10 foot; crawlspace stem wall = 6 inches × 36 inches; basement wall = 8 inches × 120 inches. Total load (TL) equal to the maximum of three load combinations: LC1=D+L, LC2=D+S and LC3=D=0.75(L+S), where D=dead load, L=live load, S=snow load. TL=max (LC1, LC2, LC3).
 
b
Use tributary span of floor and roof. Figure may be used to size exterior and interior footings.
 
c
Add 4 feet to tributary floor span for each wood framed wall above first level (i.e., 4' for 2-story, 8' for 3-story).
 
d
Multiply floor span by 1.25 for interior footings supporting continuous joists.
 
e
Multiply footing width by (1500 psf/capacity) for soil capacity other than 1500 psf. See Section R403.1.1 for thickness.
 
f
Dashed line may be used for interior footing size only.
 
g
Use footing size indicated on line above the span combination used.
 
h
For span combinations above the upper line, a design professional is required.
 
i
Interpolation between footing sizes is allowed. Extrapolation is not allowed.
Figure R403.1.1(3)
Alternative Minimum Footing Size for Light-Frame Construction a,b,c,d,e,f,g,h,i
50 PSF Snow Load
Notes:
a
The minimum footing size is based on the following assumptions: Material weights per Section R301.2.2.2.1 and soil density = 120 pcf. Wood framed walls = 10 foot; crawlspace stem wall = 6 inches × 36 inches; basement wall = 8 inches × 120 inches. Total load (TL) equal to the maximum of three load combinations: LC1=D+L, LC2=D+S and LC3=D=0.75(L+S), where D=dead load, L=live load, S=snow load. TL=max (LC1, LC2, LC3).
 
b
Use tributary span of floor and roof. Figure may be used to size exterior and interior footings.
 
c
Add 4 feet to tributary floor span for each wood framed wall above first level (i.e., 4' for 2-story, 8' for 3-story).
 
d
Multiply floor span by 1.25 for interior footings supporting continuous joists.
 
e
Multiply footing width by (1500 psf/capacity) for soil capacity other than 1500 psf. See Section R403.1.1 for thickness.
 
f
Dashed line may be used for interior footing size only.
 
g
Use footing size indicated on line above the span combination used.
 
h
For span combinations above the upper line, a design professional is required.
 
i
Interpolation between footing sizes is allowed. Extrapolation is not allowed.
Figure R403.1.1(4)
Alternative Minimum Footing Size for Light-Frame Construction a,b,c,d,e,f,g,h,i
70 PSF Snow Load
Notes:
a
The minimum footing size is based on the following assumptions: Material weights per Section R301.2.2.2.1 and soil density = 120 pcf. Wood framed walls = 10 foot; crawlspace stem wall = 6 inches × 36 inches; basement wall = 8 inches × 120 inches. Total load (TL) equal to the maximum of three load combinations: LC1=D+L, LC2=D+S and LC3=D=0.75(L+S), where D=dead load, L=live load, S=snow load. TL=max (LC1, LC2, LC3).
 
b
Use tributary span of floor and roof. Figure may be used to size exterior and interior footings.
 
c
Add 4 feet to tributary floor span for each wood framed wall above first level (i.e., 4' for 2-story, 8' for 3-story).
 
d
Multiply floor span by 1.25 for interior footings supporting continuous joists.
 
e
Multiply footing width by (1500 psf/capacity) for soil capacity other than 1500 psf. See Section R403.1.1 for thickness.
 
f
Dashed line may be used for interior footing size only.
 
g
Use footing size indicated on line above the span combination used.
 
h
For span combinations above the upper line, a design professional is required.
 
i
Interpolation between footing sizes is allowed. Extrapolation is not allowed.