Page 171 - 2018_IRC

FLOORS

SECTION R504 bers shall be in accordance with the requirements of this sec-
PRESSURE PRESERVATIVE- tion.
TREATED WOOD FLOORS (ON GROUND)
R505.1.1 Applicability limits. The provisions of this sec-
R504.1 General. Pressure preservative-treated wood base- tion shall control the construction of cold-formed steel
ment floors and floors on ground shall be designed to with- floor framing for buildings not greater than 60 feet (18 288
stand axial forces and bending moments resulting from lateral mm) in length perpendicular to the joist span, not greater
soil pressures at the base of the exterior walls and floor live than 40 feet (12 192 mm) in width parallel to the joist span
and dead loads. Floor framing shall be designed to meet joist and less than or equal to three stories above grade plane.
deflection requirements in accordance with Section R301. Cold-formed steel floor framing constructed in accordance
with the provisions of this section shall be limited to sites
R504.1.1 Unbalanced soil loads. Unless special provision
is made to resist sliding caused by unbalanced lateral soil where the ultimate design wind speed is less than 140
loads, wood basement floors shall be limited to applica- miles per hour (63 m/s), Exposure Category B or C, and
tions where the differential depth of fill on opposite exte- the ground snow load is less than or equal to 70 pounds
rior foundation walls is 2 feet (610 mm) or less. per square foot (3.35 kPa).
R504.1.2 Construction. Joists in wood basement floors R505.1.2 In-line framing. Where supported by cold-
shall bear tightly against the narrow face of studs in the formed steel-framed walls in accordance with Section
foundation wall or directly against a band joist that bears on R603, cold-formed steel floor framing shall be constructed
the studs. Plywood subfloor shall be continuous over with floor joists located in-line with load-bearing studs
lapped joists or over butt joints between in-line joists. Suf- located below the joists in accordance with Figure
ficient blocking shall be provided between joists to transfer R505.1.2 and the tolerances specified as follows:
lateral forces at the base of the end walls into the floor sys- 1. The maximum tolerance shall be / inch (19.1 mm)
3
4
tem. between the centerline of the horizontal framing
R504.1.3 Uplift and buckling. Where required, resistance member and the centerline of the vertical framing
to uplift or restraint against buckling shall be provided by member.
interior bearing walls or properly designed stub walls 2. Where the centerline of the horizontal framing
anchored in the supporting soil below. member and bearing stiffener are located to one side
R504.2 Site preparation. The area within the foundation of the centerline of the vertical framing member, the
1
walls shall have all vegetation, topsoil and foreign material maximum tolerance shall be / inch (3 mm) between
8
removed, and any fill material that is added shall be free of the web of the horizontal framing member and the
vegetation and foreign material. The fill shall be compacted edge of the vertical framing member.
to ensure uniform support of the pressure preservative-
treated wood floor sleepers. R505.1.3 Floor trusses. Cold-formed steel trusses shall be
designed, braced and installed in accordance with AISI
R504.2.1 Base. A minimum 4-inch-thick (102 mm) granu- S240. In the absence of specific bracing requirements,
lar base of gravel having a maximum size of / inch (19.1 trusses shall be braced in accordance with accepted indus-
3
4
mm) or crushed stone having a maximum size of / inch try practices, such as the SBCA Cold-Formed Steel Build-
1
2
(12.7 mm) shall be placed over the compacted earth. ing Component Safety Information (CFSBCSI), Guide to
R504.2.2 Moisture barrier. Polyethylene sheeting of min- Good Practice for Handling, Installing & Bracing of
imum 6-mil (0.15 mm) thickness shall be placed over the Cold-Formed Steel Trusses. Truss members shall not be
granular base. Joints shall be lapped 6 inches (152 mm) and notched, cut or altered in any manner without an approved
left unsealed. The polyethylene membrane shall be placed design.
over the pressure preservative-treated wood sleepers and R505.2 Structural framing. Load-bearing cold-formed steel
shall not extend beneath the footing plates of the exterior floor framing members shall be in accordance with this sec-
walls. tion.
R504.3 Materials. Framing materials, including sleepers, R505.2.1 Material. Load-bearing cold-formed steel fram-
joists, blocking and plywood subflooring, shall be pressure- ing members shall be cold formed to shape from structural
preservative treated and dried after treatment in accordance quality sheet steel complying with the requirements of
with AWPA U1 (Commodity Specification A, Special ASTM A1003: Structural Grades 33 Type H and 50 Type
Requirement 4.2), and shall bear the label of an accredited H.
agency.
R505.2.2 Corrosion protection. Load-bearing cold-
formed steel framing shall have a metallic coating comply-
SECTION R505 ing with ASTM A1003 and one of the following:
COLD-FORMED STEEL FLOOR FRAMING
R505.1 Cold-formed steel floor framing. Elements shall be 1. Not less than G 60 in accordance with ASTM A653.
straight and free of any defects that would significantly affect 2. Not less than AZ 50 in accordance with ASTM
structural performance. Cold-formed steel floor framing mem- A792.

146 2018 INTERNATIONAL RESIDENTIAL CODE ®
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