Page 154 - 2018_IRC

FOUNDATIONS

R404.1.7 Backfill placement. Backfill shall not be placed R404.1.9.5 Masonry piers in flood hazard areas.
against the wall until the wall has sufficient strength and Masonry piers for dwellings in flood hazard areas shall
has been anchored to the floor above, or has been suffi- be designed in accordance with Section R322.
ciently braced to prevent damage by the backfill. R404.2 Wood foundation walls. Wood foundation walls
Exception: Bracing is not required for walls supporting shall be constructed in accordance with the provisions of Sec-
less than 4 feet (1219 mm) of unbalanced backfill. tions R404.2.1 through R404.2.6 and with the details shown
in Figures R403.1(2) and R403.1(3).
R404.1.8 Rubble stone masonry. Rubble stone masonry
foundation walls shall have a minimum thickness of 16 R404.2.1 Identification. Load-bearing lumber shall be
inches (406 mm), shall not support an unbalanced backfill identified by the grade mark of a lumber grading or
exceeding 8 feet (2438 mm) in height, shall not support a inspection agency that has been approved by an accredita-
soil pressure greater than 30 pounds per square foot per tion body that complies with DOC PS 20. In lieu of a
foot (4.71 kPa/m), and shall not be constructed in Seismic grade mark, a certificate of inspection issued by a lumber
Design Categories D , D , D or townhouses in Seismic grading or inspection agency meeting the requirements of
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Design Category C, as established in Figure R301.2(2). this section shall be accepted. Wood structural panels shall
conform to DOC PS 1 or DOC PS 2 and shall be identified
R404.1.9 Isolated masonry piers. Isolated masonry piers by a grade mark or certificate of inspection issued by an
shall be constructed in accordance with this section and approved agency.
the general masonry construction requirements of Section
R606. Hollow masonry piers shall have a minimum nomi- R404.2.2 Stud size. The studs used in foundation walls
nal thickness of 8 inches (203 mm), with a nominal height shall be 2-inch by 6-inch (51 mm by 152 mm) members.
not exceeding four times the nominal thickness and a nom- Where spaced 16 inches (406 mm) on center, a wood spe-
inal length not exceeding three times the nominal thick- cies with an F value of not less than 1,250 pounds per
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ness. Where hollow masonry units are solidly filled with square inch (8619 kPa) as listed in ANSI AWC NDS shall
concrete or grout, piers shall be permitted to have a nomi- be used. Where spaced 12 inches (305 mm) on center, an
nal height not exceeding ten times the nominal thickness. F of not less than 875 psi (6033 kPa) shall be required.
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Footings for isolated masonry piers shall be sized in accor- R404.2.3 Height of backfill. For wood foundations that are
dance with Section R403.1.1. not designed and installed in accordance with AWC PWF,
the height of backfill against a foundation wall shall not
R404.1.9.1 Pier cap. Hollow masonry piers shall be
capped with 4 inches (102 mm) of solid masonry or exceed 4 feet (1219 mm). Where the height of fill is more
concrete, a masonry cap block, or shall have cavities of than 12 inches (305 mm) above the interior grade of a crawl
the top course filled with concrete or grout. Where space or floor of a basement, the thickness of the plywood
required, termite protection for the pier cap shall be sheathing shall meet the requirements of Table R404.2.3.
provided in accordance with Section R318. R404.2.4 Backfilling. Wood foundation walls shall not be
backfilled until the basement floor and first floor have
R404.1.9.2 Masonry piers supporting floor girders.
Masonry piers supporting wood girders sized in accor- been constructed or the walls have been braced. For crawl
space construction, backfill or bracing shall be installed on
dance with Tables R602.7(1) and R602.7(2) shall be the interior of the walls prior to placing backfill on the
permitted in accordance with this section. Piers sup- exterior.
porting girders for interior bearing walls shall have a
minimum nominal dimension of 12 inches (305 mm) R404.2.5 Drainage and dampproofing. Wood founda-
and a maximum height of 10 feet (3048 mm) from top tion basements shall be drained and dampproofed in accor-
of footing to bottom of sill plate or girder. Piers sup- dance with Sections R405 and R406, respectively.
porting girders for exterior bearing walls shall have a R404.2.6 Fastening. Wood structural panel foundation
minimum nominal dimension of 12 inches (305 mm) wall sheathing shall be attached to framing in accordance
and a maximum height of 4 feet (1220 mm) from top of with Table R602.3(1) and Section R402.1.1.
footing to bottom of sill plate or girder. Girders and sill
plates shall be anchored to the pier or footing in accor- R404.3 Wood sill plates. Wood sill plates shall be not less
dance with Section R403.1.6 or Figure R404.1.5(1). than 2-inch by 4-inch (51 mm by 102 mm) nominal lumber.
Floor girder bearing shall be in accordance with Sec- Sill plate anchorage shall be in accordance with Sections
tion R502.6. R403.1.6 and R602.11.
R404.1.9.3 Masonry piers supporting braced wall R404.4 Retaining walls. Retaining walls that are not later-
ally supported at the top and that retain in excess of 48 inches
panels. Masonry piers supporting braced wall panels (1219 mm) of unbalanced fill, or retaining walls exceeding 24
shall be designed in accordance with accepted engi-
neering practice. inches (610 mm) in height that resist lateral loads in addition
to soil, shall be designed in accordance with accepted engi-
R404.1.9.4 Seismic design of masonry piers. neering practice to ensure stability against overturning, slid-
Masonry piers in dwellings located in Seismic Design ing, excessive foundation pressure and water uplift. Retaining
Category D , D or D , and townhouses in Seismic walls shall be designed for a safety factor of 1.5 against lat-
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Design Category C, shall be designed in accordance eral sliding and overturning. This section shall not apply to
with accepted engineering practice. foundation walls supporting buildings.
2018 INTERNATIONAL RESIDENTIAL CODE ® 129
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