PERMANENT RULES
Effective Date of Rule: July 1, 2011.
Purpose: To implement changes to the Washington State Residential Code (chapter 51-51 WAC) to clarify issues around foundations and retaining walls.
Citation of Existing Rules Affected by this Order: Amending WAC 51-51-0403 and 51-51-0404.
Statutory Authority for Adoption: Chapter 19.27 RCW.
Adopted under notice filed as WSR 10-16-095 on July 30, 2010.
A final cost-benefit analysis is available by contacting Tim Nogler, P.O. Box 41011, Olympia, WA 98504-1011, phone (360) 902-7296, fax (360) 586-0493, e-mail tim.nogler@ga.wa.gov.
Number of Sections Adopted in Order to Comply with Federal Statute: New 0, Amended 0, Repealed 0; Federal Rules or Standards: New 0, Amended 0, Repealed 0; or Recently Enacted State Statutes: New 0, Amended 0, Repealed 0.
Number of Sections Adopted at Request of a Nongovernmental Entity: New 0, Amended 0, Repealed 0.
Number of Sections Adopted on the Agency's Own Initiative: New 0, Amended 2, Repealed 0.
Number of Sections Adopted in Order to Clarify, Streamline, or Reform Agency Procedures: New 0, Amended 0, Repealed 0.
Number of Sections Adopted Using Negotiated Rule Making: New 0, Amended 0, Repealed 0; Pilot Rule Making: New 0, Amended 0, Repealed 0; or Other Alternative Rule Making: New 0, Amended 2, Repealed 0.
Date Adopted: October 15, 2010.
John C. Cochran
Chair
OTS-3501.2
AMENDATORY SECTION(Amending WSR 10-03-098, filed 1/20/10,
effective 7/1/10)
WAC 51-51-0403
Section R403 -- Footings.
R403.1 General. All exterior walls shall be supported on
continuous solid or fully grouted masonry or concrete
footings, wood foundations, or other approved structural
systems which shall be of sufficient design to accommodate all
loads specified in Section R301 and to transmit the resulting
loads to the supporting soil within the limitations determined
from the characteristics of the soil. Footings shall be
supported on undisturbed natural soil or engineered fill.
Foundation walls complying with Section R404 or stem walls
complying with Section R403.1.3 shall be permitted to support
exterior walls, exterior braced wall lines and exterior braced
wall panels provided they are supported by continuous
footings.
MINIMUM WIDTH OF CONCRETE,
PRECAST OR MASONRY FOOTINGS
(inches)
| LOAD-BEARING VALUE OF SOIL (psf) | ||||||||
| 1,500 | 2,000 | 3,000 | ≥4,000 | |||||
| Conventional light-frame construction | ||||||||
| 1 floorb,c | 12 | 12 | 12 | 12 | ||||
| 2 floorsb,c | 15 | 12 | 12 | 12 | ||||
| 3 floorsb,c | 23 | 17 | 12 | 12 | ||||
| 4-inch brick veneer over light frame or 8-inch hollow concrete masonry | ||||||||
| 1-story | 12 | 12 | 12 | 12 | ||||
| 2-story | 21 | 16 | 12 | 12 | ||||
| 3-story | 32 | 24 | 16 | 12 | ||||
| 8-inch solid or fully grouted masonry | ||||||||
| 1-story | 16 | 12 | 12 | 12 | ||||
| 2-story | 29 | 21 | 14 | 12 | ||||
| 3-story | 42 | 32 | 21 | 16 | ||||
| For SI: | 1 inch = 25.4 mm, 1 pound per square foot = 0.0479kPa. |
| a. Where minimum footing width is 12 inches, use of a single wythe of solid or fully grouted 12-inch nominal concrete masonry units is permitted. | |
| b. Represents the number of floors supported. | |
| c. Footings shall be permitted to support a roof in addition to the stipulated number of floors. Footings supporting a roof only shall be as required for supporting one floor. |
Figure 403.4(1). Note corrected title and labels:
BASEMENT OR CRAWL SPACE WITH PRECAST CONCRETE FOUNDATION WALL BEARING ON CRUSHED STONE
PRECAST CONCRETE FOUNDATION WALL
CRUSHED STONE FOOTING
Figure 403.4(2). Note corrected title and label:
BASEMENT OR CRAWL SPACE WITH PRECAST CONCRETE FOUNDATION WALL ON SPREAD FOOTING
PRECAST CONCRETE FOUNDATION WALL
[Statutory Authority: RCW 19.27.031 and 19.27.074. 10-03-098, § 51-51-0403, filed 1/20/10, effective 7/1/10. Statutory Authority: RCW 19.27.190, 19.27.020, and chapters 19.27 and 34.05 RCW. 08-01-103, § 51-51-0403, filed 12/18/07, effective 4/1/08. Statutory Authority: RCW 19.27.074, 19.27.020, and chapters 19.27 and 34.05 RCW. 07-01-090, § 51-51-0403, filed 12/19/06, effective 7/1/07.]
Table R404.1.1(3). Note corrected title:
10-INCH MASONRY FOUNDATION WALLS WITH REINFORCING WHERE d > 6.75 INCHESa,c
R404.1.2.2 Reinforcement for foundation walls. Concrete
foundation walls shall be laterally supported at the top
except where permitted in R404.1.2.2.1 and R404.1.2.2.2, and
at the bottom where required elsewhere in this code.
Horizontal reinforcement shall be provided in accordance with
Table R404.1.2(1). Vertical reinforcement shall be provided
in accordance with Table R404.1.2(2), R404.1.2(3),
R404.1.2(4), R404.1.2(5), R404.1.2(6), R404.1.2(7) or
R404.1.2(8). Vertical reinforcement for flat basement walls
retaining 4 feet (1,219 mm) or more of unbalanced backfill is
permitted to be determined in accordance with Table
R404.1.2(9).
For basement walls supporting above-grade concrete walls,
vertical reinforcement shall be the greater of that required
by Tables R404.1.2(2) through R404.1.2(8) or by Section 611.6
for the above-grade wall. In buildings assigned to Seismic
Design Category D0, D1 or D2, concrete foundation walls shall
also comply with Section R404.1.4.2.
R404.4 Retaining Walls. Retaining walls not supporting a
structure that are not laterally supported at the top and that
retain in excess of 24 inches (610 mm) of unbalanced fill
shall be designed to ensure stability against overturning,
sliding, excessive foundation pressure and water uplift.
Retaining walls shall be designed for a safety factor of 1.5
against lateral sliding and overturning.
[Statutory Authority: RCW 19.27.031 and 19.27.074. 10-03-098, § 51-51-0404, filed 1/20/10, effective 7/1/10. Statutory Authority: RCW 19.27.190, 19.27.020, and chapters 19.27 and 34.05 RCW. 08-01-102, § 51-51-0404, filed 12/18/07, effective 4/1/08. Statutory Authority: RCW 19.27.074, 19.27.020, and chapters 19.27 and 34.05 RCW. 07-01-090, § 51-51-0404, filed 12/19/06, effective 7/1/07.]