The provisions of this chapter shall control the design and construction of the floors for all buildings including the floors of attic spaces used to house mechanical or plumbing fixtures and equipment.
Floor construction shall be capable of accommodating all loads according to Section R301 and of transmitting the resulting loads to the supporting structural elements.
Floor assemblies, not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wallboard membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member.
Exceptions:
Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section P2904, NFPA13D, or other approved equivalent sprinkler system.
Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.
Portions of floor assemblies can be unprotected when complying with the following:
The aggregate area of the unprotected portions shall not exceed 80 square feet per story
Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.
Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.
Load-bearing dimension lumber for joists, beams and girders shall be identified by a grademark of a lumber grading or inspection agency that has been approvedby an accreditation body that complies with DOC PS 20. In lieu of a grademark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted.
Approvedend-jointed lumber identified by a grademark conforming to Section R502.1 may be used interchangeably with solid-sawn members of the same species and grade. End-jointed lumber used in an assembly required elsewhere in this code to have a fire-resistance rating shall have the designation "Heat Resistant Adhesive" or "HRA" included in its grade mark.
Stress grading of structural log members of nonrectangular shape, as typically used in log buildings, shall be in accordance with ASTM D 3957. Such structural log members shall be identified by the grademark of an approvedlumber grading or inspection agency. In lieu of a grademark on the material, a certificate of inspection as to species and grade issued by a lumber-grading or inspection agency meeting the requirements of this section shall be permitted to be accepted.
Floors shall be designed and constructed in accordance with the provisions of this chapter, Figure R502.2 and Sections R317 and R318 or in accordance with AF&PA;/NDS.
A load path for lateral forces shall be provided between floor framing and braced wall panels located above or below a floor, as specified in Section R602.10.8.
Spans for floor joists shall be in accordance with Tables R502.3.1(1) and R502.3.1(2). For other grades and species and for other loading conditions, refer to the AF&PA; Span Tables for Joists and Rafters.
Table R502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section R311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds per square foot (0.96 kPa). The allowable span of ceiling joists that support attics used for limited storage or no storage shall be determined in accordance with Section R802.4.
TABLE R502.3.1(1) FLOOR JOIST SPANS FOR COMMON LUMBER SPECIES (Residential sleeping areas, live load = 30 psf, L/Δ = 360)a
Table R502.3.1(2) shall be used to determine the maximum allowable span of floor joists that support all other areas of the building, other than sleeping rooms and attics, provided that the design live load does not exceed 40 pounds per square foot (1.92 kPa) and the design dead load does not exceed 20 pounds per square foot (0.96 kPa).
Floor cantilever spans shall not exceed the nominal depth of the wood floor joist. Floor cantilevers constructed in accordance with Table R502.3.3(1) shall be permitted when supporting a light-frame bearing wall and roof only. Floor cantilevers supporting an exterior balcony are permitted to be constructed in accordance with Table R502.3.3(2)
TABLE R502.3.3(1) CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING LIGHT-FRAME EXTERIOR BEARING WALL AND ROOF ONLYa, b, c, f, g, h (Floor Live Load ≤ 40 psf, Roof Live Load ≤ 20 psf)
Member & Spacing
Maximum Cantilever Span (Uplift Force at Backspan Support in Lbs.)d, e
Ground Snow Load
≤ 20 psf
30 psf
50 psf
70 psf
Roof Width
Roof Width
Roof Width
Roof Width
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
24 ft
32 ft
40 ft
2 × 8 @ 12"
20"(177)
15"(227)
—
18"(209)
—
—
—
—
—
—
—
—
2 × 10 @ 16"
29"(228)
21"(297)
16"(364)
26"(271)
18"(354)
—
20"(375)
—
—
—
—
—
2 × 10 @ 12"
36"(166)
26"(219)
20"(270)
34"(198)
22"(263)
16"(324)
26"(277)
—
—
19"(356)
—
—
2 × 12 @ 16"
—
32"(287)
25"(356)
36"(263)
29"(345)
21"(428)
29"(367)
20"(484)
—
23"(471)
—
—
2 × 12 @ 12"
—
42"(209)
31"(263)
—
37"(253)
27"(317)
36"(271)
27"(358)
17"(447)
31"(348)
19"(462)
—
2 × 12 @ 8"
—
48"(136)
45"(169)
—
48"(164)
38"(206)
—
40"(233)
26"(294)
36"(230)
29"(304)
18"(379)
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Tabulated values are for clear-span roof supported solely by exterior bearing walls.
Spans are based on No. 2 Grade lumber of Douglas fir-larch, hem-fir, southern pine and spruce-pine-fir for repetitive (three or more) members.
Ratio of backspan to cantilever span shall be at least 3:1.
Connections capable of resisting the indicated uplift force shall be provided at the backspan support.
Uplift force is for a backspan to cantilever span ratio of 3:1. Tabulated uplift values are permitted to be reduced by multiplying by a factor equal to 3 divided by the actual backspan ratio provided (3/backspan ratio).
A full-depth rim joist shall be provided at the unsupported end of the cantilever joists. Solid blocking shall be provided at the supported end.
Linear interpolation shall be permitted for building widths and ground snow loads other than shown.
TABLE R502.3.3(2) CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING EXTERIOR BALCONYa, b, e, f
Member Size
Spacing
Maximum Cantilever Span (Uplift Force at Backspan Support in lb)c, d
Ground Snow Load
≤ 30 psf
50 psf
70 psf
2 × 8
12"
42" (139)
39" (156)
34" (165)
2 × 8
16"
36" (151)
34" (171)
29" (180)
2 × 10
12"
61" (164)
57" (189)
49" (201)
2 × 10
16"
53" (180)
49" (208)
42" (220)
2 × 10
24"
43" (212)
40" (241)
34" (255)
2 × 12
16"
72" (228)
67" (260)
57" (268)
2 × 12
24"
58" (279)
54" (319)
47" (330)
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
Spans are based on No. 2 Grade lumber of Douglas fir-larch, hem-fir, southern pine and spruce-pine-fir for repetitive (three or more) members.
Ratio of backspan to cantilever span shall be at least 2:1.
Connections capable of resisting the indicated uplift force shall be provided at the backspan support.
Uplift force is for a backspan to cantilever span ratio of 2:1. Tabulated uplift values are permitted to be reduced by multiplying by a factor equal to 2 divided by the actual backspan ratio provided (2/backspan ratio).
A full-depth rim joist shall be provided at the unsupported end of the cantilever joists. Solid blocking shall be provided at the supported end.
Linear interpolation shall be permitted for ground snow loads other than shown.
Joists under parallel bearing partitions shall be of adequate size to support the load. Double joists, sized to adequately support the load, that are separated to permit the installation of piping or vents shall be full depth solid blocked with lumber not less than 2 inches (51 mm) in nominal thickness spaced not more than 4 feet (1219 mm) on center. Bearing partitions perpendicular to joists shall not be offset from supporting girders, walls or partitions more than the joist depth unless such joists are of sufficient size to carry the additional load.
The allowable spans of girders fabricated of dimension lumber shall not exceed the values set forth in Tables R502.5(1) and R502.5(2).
TABLE R502.5(1) GIRDER SPANSa AND HEADER SPANSa FOR EXTERIOR BEARING WALLS (Maximum spans for Douglas fir-larch, hem-fir, southern pine and spruce-pine-firb and required number of jack studs)
GIRDERS AND HEADERS SUPPORTING
SIZE
GROUND SNOW LOAD (psf)e
30
50
70
Building widthc (feet)
20
28
36
20
28
36
20
28
36
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Span
NJd
Roof and ceiling
2-2 × 4
3-6
1
3-2
1
2-10
1
3-2
1
2-9
1
2-6
1
2-10
1
2-6
1
2-3
1
2-2 × 6
5-5
1
4-8
1
4-2
1
4-8
1
4-1
1
3-8
2
4-2
1
3-8
2
3-3
2
2-2 × 8
6-10
1
5-11
2
5-4
2
5-11
2
5-2
2
4-7
2
5-4
2
4-7
2
4-1
2
2-2 × 10
8-5
2
7-3
2
6-6
2
7-3
2
6-3
2
5-7
2
6-6
2
5-7
2
5-0
2
2-2 × 12
9-9
2
8-5
2
7-6
2
8-5
2
7-3
2
6-6
2
7-6
2
6-6
2
5-10
3
3-2 × 8
8-4
1
7-5
1
6-8
1
7-5
1
6-5
2
5-9
2
6-8
1
5-9
2
5-2
2
3-2 × 10
10-6
1
9-1
2
8-2
2
9-1
2
7-10
2
7-0
2
8-2
2
7-0
2
6-4
2
3-2 × 12
12-2
2
10-7
2
9-5
2
10-7
2
9-2
2
8-2
2
9-5
2
8-2
2
7-4
2
4-2 × 8
9-2
1
8-4
1
7-8
1
8-4
1
7-5
1
6-8
1
7-8
1
6-8
1
5-11
2
4-2 × 10
11-8
1
10-6
1
9-5
2
10-6
1
9-1
2
8-2
2
9-5
2
8-2
2
7-3
2
4-2 × 12
14-1
1
12-2
2
10-11
2
12-2
2
10-7
2
9-5
2
10-11
2
9-5
2
8-5
2
Roof, ceiling and one center- bearing floor
2-2 × 4
3-1
1
2-9
1
2-5
1
2-9
1
2-5
1
2-2
1
2-7
1
2-3
1
2-0
1
2-2 × 6
4-6
1
4-0
1
3-7
2
4-1
1
3-7
2
3-3
2
3-9
2
3-3
2
2-11
2
2-2 × 8
5-9
2
5-0
2
4-6
2
5-2
2
4-6
2
4-1
2
4-9
2
4-2
2
3-9
2
2-2 × 10
7-0
2
6-2
2
5-6
2
6-4
2
5-6
2
5-0
2
5-9
2
5-1
2
4-7
3
2-2 × 12
8-1
2
7-1
2
6-5
2
7-4
2
6-5
2
5-9
3
6-8
2
5-10
3
5-3
3
3-2 × 8
7-2
1
6-3
2
5-8
2
6-5
2
5-8
2
5-1
2
5-11
2
5-2
2
4-8
2
3-2 × 10
8-9
2
7-8
2
6-11
2
7-11
2
6-11
2
6-3
2
7-3
2
6-4
2
5-8
2
3-2 × 12
10-2
2
8-11
2
8-0
2
9-2
2
8-0
2
7-3
2
8-5
2
7-4
2
6-7
2
4-2 × 8
8-1
1
7-3
1
6-7
1
7-5
1
6-6
1
5-11
2
6-10
1
6-0
2
5-5
2
4-2 × 10
10-1
1
8-10
2
8-0
2
9-1
2
8-0
2
7-2
2
8-4
2
7-4
2
6-7
2
4-2 × 12
11-9
2
10-3
2
9-3
2
10-7
2
9-3
2
8-4
2
9-8
2
8-6
2
7-7
2
Roof, ceiling and one clear span floor
2-2 × 4
2-8
1
2-4
1
2-1
1
2-7
1
2-3
1
2-0
1
2-5
1
2-1
1
1-10
1
2-2 × 6
3-11
1
3-5
2
3-0
2
3-10
2
3-4
2
3-0
2
3-6
2
3-1
2
2-9
2
2-2 × 8
5-0
2
4-4
2
3-10
2
4-10
2
4-2
2
3-9
2
4-6
2
3-11
2
3-6
2
2-2 × 10
6-1
2
5-3
2
4-8
2
5-11
2
5-1
2
4-7
3
5-6
2
4-9
2
4-3
3
2-2 × 12
7-1
2
6-1
3
5-5
3
6-10
2
5-11
3
5-4
3
6-4
2
5-6
3
5-0
3
3-2 × 8
6-3
2
5-5
2
4-10
2
6-1
2
5-3
2
4-8
2
5-7
2
4-11
2
4-5
2
3-2 × 10
7-7
2
6-7
2
5-11
2
7-5
2
6-5
2
5-9
2
6-10
2
6-0
2
5-4
2
3-2 × 12
8-10
2
7-8
2
6-10
2
8-7
2
7-5
2
6-8
2
7-11
2
6-11
2
6-3
2
4-2 × 8
7-2
1
6-3
2
5-7
2
7-0
1
6-1
2
5-5
2
6-6
1
5-8
2
5-1
2
4-2 × 10
8-9
2
7-7
2
6-10
2
8-7
2
7-5
2
6-7
2
7-11
2
6-11
2
6-2
2
4-2 × 12
10-2
2
8-10
2
7-11
2
9-11
2
8-7
2
7-8
2
9-2
2
8-0
2
7-2
2
Roof, ceiling and two center- bearing floors
2-2 × 4
2-7
1
2-3
1
2-0
1
2-6
1
2-2
1
1-11
1
2-4
1
2-0
1
1-9
1
2-2 × 6
3-9
2
3-3
2
2-11
2
3-8
2
3-2
2
2-10
2
3-5
2
3-0
2
2-8
2
2-2 × 8
4-9
2
4-2
2
3-9
2
4-7
2
4-0
2
3-8
2
4-4
2
3-9
2
3-5
2
2-2 × 10
5-9
2
5-1
2
4-7
3
5-8
2
4-11
2
4-5
3
5-3
2
4-7
3
4-2
3
2-2 × 12
6-8
2
5-10
3
5-3
3
6-6
2
5-9
3
5-2
3
6-1
3
5-4
3
4-10
3
3-2 × 8
5-11
2
5-2
2
4-8
2
5-9
2
5-1
2
4-7
2
5-5
2
4-9
2
4-3
2
3-2 × 10
7-3
2
6-4
2
5-8
2
7-1
2
6-2
2
5-7
2
6-7
2
5-9
2
5-3
2
3-2 × 12
8-5
2
7-4
2
6-7
2
8-2
2
7-2
2
6-5
3
7-8
2
6-9
2
6-1
3
4-2 × 8
6-10
1
6-0
2
5-5
2
6-8
1
5-10
2
5-3
2
6-3
2
5-6
2
4-11
2
4-2 × 10
8-4
2
7-4
2
6-7
2
8-2
2
7-2
2
6-5
2
7-7
2
6-8
2
6-0
2
4-2 × 12
9-8
2
8-6
2
7-8
2
9-5
2
8-3
2
7-5
2
8-10
2
7-9
2
7-0
2
Roof, ceiling, and two clear span floors
2-2 × 4
2-1
1
1-8
1
1-6
2
2-0
1
1-8
1
1-5
2
2-0
1
1-8
1
1-5
2
2-2 × 6
3-1
2
2-8
2
2-4
2
3-0
2
2-7
2
2-3
2
2-11
2
2-7
2
2-3
2
2-2 × 8
3-10
2
3-4
2
3-0
3
3-10
2
3-4
2
2-11
3
3-9
2
3-3
2
2-11
3
Roof, ceiling, and two clear span floors
2-2 × 10
4-9
2
4-1
3
3-8
3
4-8
2
4-0
3
3-7
3
4-7
3
4-0
3
3-6
3
2-2 × 12
5-6
3
4-9
3
4-3
3
5-5
3
4-8
3
4-2
3
5-4
3
4-7
3
4-1
4
3-2 × 8
4-10
2
4-2
2
3-9
2
4-9
2
4-1
2
3-8
2
4-8
2
4-1
2
3-8
2
3-2 × 10
5-11
2
5-1
2
4-7
3
5-10
2
5-0
2
4-6
3
5-9
2
4-11
2
4-5
3
3-2 × 12
6-10
2
5-11
3
5-4
3
6-9
2
5-10
3
5-3
3
6-8
2
5-9
3
5-2
3
4-2 × 8
5-7
2
4-10
2
4-4
2
5-6
2
4-9
2
4-3
2
5-5
2
4-8
2
4-2
2
4-2 × 10
6-10
2
5-11
2
5-3
2
6-9
2
5-10
2
5-2
2
6-7
2
5-9
2
5-1
2
4-2 × 12
7-11
2
6-10
2
6-2
3
7-9
2
6-9
2
6-0
3
7-8
2
6-8
2
5-11
3
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
Building width is measured perpendicular to the ridge. For widths between those shown, spans are permitted to be interpolated.
NJ - Number of jack studs required to support each end. Where the number of required jack studs equals one, the header is permitted to be supported by an approved framing anchor attached to the full-height wall stud and to the header.
Use 30 psf ground snow load for cases in which ground snow load is less than 30 psf and the roof live load is equal to or less than 20 psf.
TABLE R502.5(2) GIRDER SPANSa AND HEADER SPANSa FOR INTERIOR BEARING WALLS (Maximum spans for Douglas fir-larch, hem-fir, southern pine and spruce-pine-firb and required number of jack studs)
Building width is measured perpendicular to the ridge. For widths between those shown, spans are permitted to be interpolated.
NJ - Number of jack studs required to support each end. Where the number of required jack studs equals one, the header is permitted to be supported by an approved framing anchor attached to the full-height wall stud and to the header.
The ends of each joist, beam or girder shall have not less than 1.5 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete except where supported on a 1-inch by 4-inch (25.4 mm by 102 mm) ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch-minimum (51 mm) nominal thickness shall be provided under the joist, beam or girder. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 865 square mm).
Joists framing from opposite sides over a bearing support shall lap a minimum of 3 inches (76 mm) and shall be nailed together with a minimum three 10d face nails. A wood or metal splice with strength equal to or greater than that provided by the nailed lap is permitted.
Joists framing into the side of a wood girder shall be supported by approvedframing anchors or on ledger strips not less than nominal 2 inches by 2 inches (51 mm by 51 mm).
Joists shall be supported laterally at the ends by full-depth solid blocking not less than 2 inches (51 mm) nominal in thickness; or by attachment to a full-depth header, band or rim joist, or to an adjoining stud or shall be otherwise provided with lateral support to prevent rotation.
Exceptions:
Trusses, structural composite lumber, structural glued-laminated members and I-joists shall be supported laterally as required by the manufacturer's recommendations.
In Seismic Design Categories D0, D1 and D2, lateral restraint shall also be provided at each intermediate support.
Joists exceeding a nominal 2 inches by 12 inches (51 mm by 305 mm) shall be supported laterally by solid blocking, diagonal bridging (wood or metal), or a continuous 1 inch by 3 inch (25.4 mm by 76 mm) strip nailed across the bottom of joists perpendicular to joists at intervals not exceeding 8 feet (2438 mm).
Exception: Trusses, structural composite lumber, structural glued-laminated members and I-joists shall be supported laterally as required by the manufacturer's recommendations.
Notches in solid lumber joists, rafters and beams shall not exceed one-sixth of the depth of the member, shall not be longer than one-third of the depth of the member and shall not be located in the middle one-third of the span. Notches at the ends of the member shall not exceed one-fourth the depth of the member. The tension side of members 4 inches (102 mm) or greater in nominal thickness shall not be notched except at the ends of the members. The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches (51 mm) to the top or bottom of the member, or to any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches (51 mm) to the notch.
Cuts, notches and holes bored in trusses, structural composite lumber, structural glue-laminated members or I-joists are prohibited except where permitted by the manufacturer's recommendations or where the effects of such alterations are specifically considered in the design of the member by a registered design professional.
Floor framing shall be nailed in accordance with Table R602.3(1). Where posts and beam or girder construction is used to support floor framing, positive connections shall be provided to ensure against uplift and lateral displacement.
Openings in floor framing shall be framed with a header and trimmer joists. When the header joist span does not exceed 4 feet (1219 mm), the header joist may be a single member the same size as the floor joist. Single trimmer joists may be used to carry a single header joist that is located within 3 feet (914 mm) of the trimmer joist bearing. When the header joist span exceeds 4 feet (1219 mm), the trimmer joists and the header joist shall be doubled and of sufficient cross section to support the floor joists framing into the header. Approvedhangers shall be used for the header joist to trimmer joist connections when the header joist span exceeds 6 feet (1829 mm). Tail joists over 12 feet (3658 mm) long shall be supported at the header by framing anchors or on ledger strips not less than 2 inches by 2 inches (51 mm by 51 mm).
Wood trusses shall be designed in accordance with approvedengineering practice. The design and manufacture of metal plate connected wood trusses shall comply with ANSI/TPI 1. The truss design drawings shall be prepared by a registered professional where required by the statutes of the jurisdiction in which the project is to be constructed in accordance with Section R106.1.
Trusses shall be braced to prevent rotation and provide lateral stability in accordance with the requirements specified in the construction documents for the building and on the individual truss design drawings. In the absence of specific bracing requirements, trusses shall be braced in accordance with accepted industry practices, such as, the SBCA Building Component Safety Information (BCSI) Guide to Good Practice for Handling, Installing & Bracing of Metal Plate Connected Wood Trusses.
Truss members and components shall not be cut, notched, spliced or otherwise altered in any way without the approval of a registered design professional. Alterations resulting in the addition of load (e.g., HVAC equipment, water heater, etc.), that exceed the design load for the truss, shall not be permitted without verification that the truss is capable of supporting the additional loading.
Concentrated loads and their points of application; and
Controlling wind and earthquake loads.
Adjustments to lumber and joint connector design values for conditions of use.
Each reaction force and direction.
Joint connector type and description, e.g., size, thickness or gauge, and the dimensioned location of each joint connector except where symmetrically located relative to the joint interface.
Calculated deflection ratio and/or maximum description for live and total load.
Maximum axial compression forces in the truss members to enable the building designer to design the size, connections and anchorage of the permanent continuous lateral bracing. Forces shall be shown on the truss drawing or on supplemental documents.
End joints in lumber used as subflooring shall occur over supports unless end-matched lumber is used, in which case each piece shall bear on at least two joists. Subflooring may be omitted when joist spacing does not exceed 16 inches (406 mm) and a 1-inch (25.4 mm) nominal tongue-and-groove wood strip flooring is applied perpendicular to the joists.
Where used as subflooring or combination subfloor underlayment, wood structural panels shall be of one of the grades specified in Table R503.2.1.1(1). When sanded plywood is used as combination subfloor underlayment, the grade, bond classification, and Performance Category shall be as specified in Table R503.2.1.1(2).
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
The allowable total loads were determined using a dead load of 10 psf. If the dead load exceeds 10 psf, then the live load shall be reduced accordingly.
Panels continuous over two or more spans with long dimension (strength axis) perpendicular to supports. Spans shall be limited to values shown because of possible effect of concentrated loads.
Applies to panels 24 inches or wider.
Lumber blocking, panel edge clips (one midway between each support, except two equally spaced between supports when span is 48 inches), tongue-and-groove panel edges, or other approved type of edge support.
Uniform load deflection limitation: 1/180 of span under live load plus dead load, 1/240 of span under live load only.
Maximum span 24 inches for 15/32-and 1/2-inch panels.
Maximum span 24 inches where 3/4-inch wood finish flooring is installed at right angles to joists.
Maximum span 24 inches where 1.5 inches of lightweight concrete or approved cellular concrete is placed over the subfloor.
Unsupported edges shall have tongue-and-groove joints or shall be supported with blocking unless minimum nominal 1/4-inch thick underlayment with end and edge joints offset at least 2 inches or 1.5 inches of lightweight concrete or approved cellular concrete is placed over the subfloor, or 3/4-inch wood finish flooring is installed at right angles to the supports. Allowable uniform live load at maximum span, based on deflection of 1/360 of span, is 100 psf.
Unsupported edges shall have tongue-and-groove joints or shall be supported by blocking unless nominal 1/4-inch-thick underlayment with end and edge joints offset at least 2 inches or 3/4-inch wood finish flooring is installed at right angles to the supports. Allowable uniform live load at maximum span, based on deflection of 1/360 of span, is 100 psf, except panels with a span rating of 48 on center are limited to 65 psf total uniform load at maximum span.
Allowable live load values at spans of 16" o.c. and 24" o.c taken from reference standard APA E30, APA Engineered Wood Construction Guide. Refer to reference standard for allowable spans not listed in the table.
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
Plywood continuous over two or more spans and face grain perpendicular to supports. Unsupported edges shall be tongue-and-groove or blocked except where nominal 1/4-inch-thick underlayment or 3/4-inch wood finish floor is used. Allowable uniform live load at maximum span based on deflection of 1/360 of span is 100 psf.
Applicable to all grades of sanded exterior-type plywood.
Particleboard underlayment shall be installed in accordance with the recommendations of the manufacturer and attached to framing in accordance with Table R602.3(1).
Pressure preservatively treated-wood basement floors and floors on ground shall be designed to withstand axial forces and bending moments resulting from lateral soil pressures at the base of the exterior walls and floor live and dead loads. Floor framing shall be designed to meet joist deflection requirements in accordance with Section R301.
Unless special provision is made to resist sliding caused by unbalanced lateral soil loads, wood basement floors shall be limited to applications where the differential depth of fill on opposite exterior foundation walls is 2 feet (610 mm) or less.
Joists in wood basement floors shall bear tightly against the narrow face of studs in the foundation wall or directly against a band joist that bears on the studs. Plywood subfloor shall be continuous over lapped joists or over butt joints between in-line joists. Sufficient blocking shall be provided between joists to transfer lateral forces at the base of the end walls into the floor system.
Where required, resistance to uplift or restraint against buckling shall be provided by interior bearing walls or properly designed stub walls anchored in the supporting soil below.
The area within the foundation walls shall have all vegetation, topsoil and foreign material removed, and any fill material that is added shall be free of vegetation and foreign material. The fill shall be compacted to assure uniform support of the pressure preservatively treated-wood floor sleepers.
A minimum 4-inch-thick (102 mm) granular base of gravel having a maximum size of 3/4 inch (19.1 mm) or crushed stone having a maximum size of 1/2 inch (12.7 mm) shall be placed over the compacted earth.
Polyethylene sheeting of minimum 6-mil (0.15 mm) thickness shall be placed over the granular base. Joints shall be lapped 6 inches (152 mm) and left unsealed. The polyethylene membrane shall be placed over the pressure preservatively treated-wood sleepers and shall not extend beneath the footing plates of the exterior walls.
All framing materials, including sleepers, joists, blocking and plywood subflooring, shall be pressure-preservative treated and dried after treatment in accordance with AWPA U1 (Commodity Specification A, Use Category 4B and Section 5.2), and shall bear the labelof an accredited agency.
Elements shall be straight and free of any defects that would significantly affect structural performance. Cold-formed steel floor framing members shall comply with the requirements of this section.
The provisions of this section shall control the construction of cold-formed steel floor framing for buildings not greater than 60 feet (18 288 mm) in length perpendicular to the joist span, not greater than 40 feet (12 192 mm) in width parallel to the joist span, and less than or equal to three stories above grade plane. Cold-formed steel floor framing constructed in accordance with the provisions of this section shall be limited to sites subjected to a maximum design wind speed of 110 miles per hour (49 m/s), Exposure B or C, and a maximum ground snow load of 70 pounds per square foot (3.35 kPa).
When supported by cold-formed steel framed walls in accordance with Section R603, cold-formed steel floor framing shall be constructed with floor joists located in-line with load-bearing studs located below the joists in accordance with Figure R505.1.2 and the tolerances specified as follows:
The maximum tolerance shall be 3/4 inch (19.1 mm) between the centerline of the horizontal framing member and the centerline of the vertical framing member.
Where the centerline of the horizontal framing member and bearing stiffener are located to one side of the centerline of the vertical framing member, the maximum tolerance shall be 1/8 inch (3 mm) between the web of the horizontal framing member and the edge of the vertical framing member.
Cold-formed steel trusses shall be designed, braced and installed in accordance with AISI S100, Section D4. In the absence of specific bracing requirements, trusses shall be braced in accordance with accepted industry practices, such as the SBCA Cold-Formed Steel Building Component Safety Information (CFSBCSI), Guide to Good Practice for Handling, Installing & Bracing of Cold-Formed Steel Trusses. Truss members shall not be notched, cut or altered in any manner without an approveddesign.
Load-bearing cold-formed steel floor framing members shall comply with Figure R505.2(1) and with the dimensional and minimum thickness requirements specified in Tables R505.2(1) and R505.2(2). Tracks shall comply with Figure R505.2(2) and shall have a minimum flange width of 11/4 inches (32 mm).
a. The member designation is defined by the first number representing the member depth in 0.01 inch, the letter "S" representing a stud or joist member, the second number representing the flange width in 0.01 inch, and the letter "t" shall be a number representing the minimum base metal thickness in mils [See Table R505.2(2)].
TABLE R505.2(2) MINIMUM THICKNESS OF COLD-FORMED STEEL MEMBERS
Load-bearing cold-formed steel framing members shall be cold formed to shape from structural quality sheet steel complying with the requirements of one of the following:
Screws for steel-to-steel connections shall be installed with a minimum edge distance and center-to-center spacing of 1/2 inch (12.7 mm), shall be self-drilling tapping, and shall conform to ASTM C 1513. Floor sheathing shall be attached to cold-formed steel joists with minimum No. 8 self-drilling tapping screws that conform to ASTM C 1513. Screws attaching floor-sheathing to cold-formed steel joists shall have a minimum head diameter of 0.292 inch (7.4 mm) with countersunk heads and shall be installed with a minimum edge distance of 3/8 inch (9.5 mm). Gypsum board ceilings shall be attached to cold-formed steel joists with minimum No. 6 screws conforming to ASTM C 954 or ASTM C 1513 with a bugle head style and shall be installed in accordance with Section R702. For all connections, screws shall extend through the steel a minimum of three exposed threads. All fasteners shall have rust inhibitive coating suitable for the installation in which they are being used, or be manufactured from material not susceptible to corrosion.
Where No. 8 screws are specified in a steel-to-steel connection, the required number of screws in the connection is permitted to be reduced in accordance with the reduction factors in Table R505.2.4 when larger screws are used or when one of the sheets of steel being connected is thicker than 33 mils (0.84 mm). When applying the reduction factor, the resulting number of screws shall be rounded up.
Web holes in floor joists shall comply with all of the following conditions:
Holes shall conform to Figure R505.2.5.1;
Holes shall be permitted only along the centerline of the web of the framing member;
Holes shall have a center-to-center spacing of not less than 24 inches (610 mm);
Holes shall have a web hole width not greater than 0.5 times the member depth, or 21/2 inches (64.5 mm);
Holes shall have a web hole length not exceeding 41/2 inches (114 mm); and
Holes shall have a minimum distance between the edge of the bearing surface and the edge of the web hole of not less than 10 inches (254 mm).
Framing members with web holes not conforming to the above requirements shall be reinforced in accordance with Section R505.2.5.2, patched in accordance with Section R505.2.5.3 or designed in accordance with accepted engineering practices.
Reinforcement of web holes in floor joists not conforming to the requirements of Section R505.2.5.1 shall be permitted if the hole is located fully within the center 40 percent of the span and the depth and length of the hole does not exceed 65 percent of the flat width of the web. The reinforcing shall be a steel plate or C-shape section with a hole that does not exceed the web hole size limitations of Section R505.2.5.1 for the member being reinforced. The steel reinforcing shall be the same thickness as the receiving member and shall extend at least 1 inch (25.4 mm) beyond all edges of the hole. The steel reinforcing shall be fastened to the web of the receiving member with No. 8 screws spaced no more than 1 inch (25.4 mm) center-to-center along the edges of the patch with minimum edge distance of 1/2 inch (12.7 mm).
Patching of web holes in floor joists not conforming to the requirements in Section R505.2.5.1 shall be permitted in accordance with either of the following methods:
Framing members shall be replaced or designed in accordance with accepted engineering practices where web holes exceed the following size limits:
The depth of the hole, measured across the web, exceeds 70 percent of the flat width of the web; or
The length of the hole measured along the web, exceeds 10 inches (254 mm) or the depth of the web, whichever is greater.
Web holes not exceeding the dimensional requirements in Section R505.2.5.3, Item 1, shall be patched with a solid steel plate, stud section, or track section in accordance with Figure R505.2.5.3. The steel patch shall, as a minimum, be of the same thickness as the receiving member and shall extend at least 1 inch (25 mm) beyond all edges of the hole. The steel patch shall be fastened to the web of the receiving member with No. 8 screws spaced no more than 1 inch (25 mm) center-to-center along the edges of the patch with minimum edge distance of 1/2 inch (13 mm).
Cold-formed steel framed floors shall be anchored to foundations, wood sills or load-bearing walls in accordance with Table R505.3.1(1) and Figure R505.3.1(1), R505.3.1(2), R505.3.1(3), R505.3.1(4), R505.3.1(5) or R505.3.1(6). Anchor bolts shall be located not more than 12 inches (305 mm) from corners or the termination of bottom tracks. Continuous cold-formed steel joists supported by interior load-bearing walls shall be constructed in accordance with Figure R505.3.1(7). Lapped cold-formed steel joists shall be constructed in accordance with Figure R505.3.1(8). End floor joists constructed on foundation walls parallel to the joist span shall be doubled unless a C-shaped bearing stiffener, sized in accordance with Section R505.3.4, is installed web-to-web with the floor joist beneath each supported wall stud, as shown in Figure R505.3.1(9). Fastening of cold-formed steel joists to other framing members shall be in accordance with Section R505.2.4 and Table R505.3.1(2).
TABLE R505.3.1(1) FLOOR TO FOUNDATION OR BEARING WALL CONNECTION REQUIREMENTSa, b
Floor joist to wall track of exterior wall per Figure R505.3.1(1)
2-No. 8 screws
3-No. 8 screws
Rim track or end joist to load-bearing wall top track per Figure R505.3.1(1)
1-No. 8 screw at 24 inches o.c.
1-No. 8 screw at 24 inches o.c.
Rim track or end joist to wood sill per Figure R505.3.1(2)
Steel plate spaced at 4 feet o.c. with 4-No. 8 screws and 4-10d or 6-8d common nails
Steel plate spaced at 2 feet o.c. with 4-No. 8 screws and 4-10d or 6-8d common nails
Rim track or end joist to foundation per Figure R505.3.1(3)
1/2 inch minimum diameter anchor bolt and clip angle spaced at 6 feet o.c. with 8-No. 8 screws
1/2 inch minimum diameter anchor bolt and clip angle spaced at 4 feet o.c. with 8-No. 8 screws
Cantilevered joist to foundation per Figure R505.3.1(4)
1/2 inch minimum diameter anchor bolt and clip angle spaced at 6 feet o.c. with 8-No. 8 screws
1/2 inch minimum diameter anchor bolt and clip angle spaced at 4 feet o.c. with 8-No. 8 screws
Cantilevered joist to wood sill per Figure R505.3.1(5)
Steel plate spaced at 4 feet o.c. with 4-No. 8 screws and 4-10d or 6-8d common nails
Steel plate spaced at 2 feet o.c. with 4-No. 8 screws and 4-10d or 6-8d common nails
Cantilevered joist to exterior load-bearing wall track per Figure R505.3.1(6)
2-No. 8 screws
3-No. 8 screws
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa, 1 mile per hour = 0.447 m/s, 1 foot = 304.8 mm.
Anchor bolts are to be located not more than 12 inches from corners or the termination of bottom tracks (e.g., at door openings or corners). Bolts extend a minimum of 15 inches into masonry or 7 inches into concrete. Anchor bolts connecting cold-formed steel framing to the foundation structure are to be installed so that the distance from the center of the bolt hole to the edge of the connected member is not less than one and one-half bolt diameters.
Floor joist size and thickness shall be determined in accordance with the limits set forth in Table R505.3.2(1) for single spans, and Tables R505.3.2(2) and R505.3.2(3) for multiple spans. When continuous joist members are used, the interior bearing supports shall be located within 2 feet (610 mm) of mid-span of the cold-formed steel joists, and the individual spans shall not exceed the spans in Table R505.3.2(2) or R505.3.2(3), as applicable. Floor joists shall have a bearing support length of not less than 11/2 inches (38 mm) for exterior wallsupports and 31/2 inches (89 mm) for interior wall supports. Tracks shall be a minimum of 33 mils (0.84 mm) thick except when used as part of a floor header or trimmer in accordance with Section R505.3.8. Bearing stiffeners shall be installed in accordance with Section R505.3.4.
TABLE R505.3.2(1) ALLOWABLE SPANS FOR COLD-FORMED STEEL JOISTS—SINGLE SPANSa, b, c, d 33 ksi STEEL
JOIST DESIGNATION
30 PSF LIVE LOAD
40 PSF LIVE LOAD
Spacing (inches)
Spacing (inches)
12
16
19.2
24
12
16
19.2
24
550S162-33
11'-7"
10'-7"
9'-6"
8'-6"
10'-7"
9'-3"
8'-6"
7'-6"
550S162-43
12'-8"
11'-6"
10'-10"
10'-2"
11'-6"
10'-5"
9'-10"
9'-1"
550S162-54
13'-7"
12'-4"
11'-7"
10'-9"
12'-4"
11'-2"
10'-6"
9'-9"
550S162-68
14'-7"
13'-3"
12'-6"
11'-7"
13'-3"
12'-0"
11'-4"
10'-6"
550S162-97
16'-2"
14'-9"
13'-10"
12'-10"
14'-9"
13'-4"
12'-7"
11'-8"
800S162-33
15'-8"
13'-11"
12'-9"
11'-5"
14'-3"
12'-5"
11'-3"
9'-0"
800S162-43
17'-1"
15'-6"
14'-7"
13'-7"
15'-6"
14'-1"
13'-3"
12'-4"
800S162-54
18'-4"
16'-8"
15'-8"
14'-7"
16'-8"
15'-2"
14'-3"
13'-3"
800S162-68
19'-9"
17'-11"
16'-10"
15'-8"
17'-11"
16'-3"
15'-4"
14'-2"
800S162-97
22'-0"
20'-0"
16'-10"
17'-5"
20'-0"
18'-2"
17'-1"
15'-10"
1000S162-43
20'-6"
18'-8"
17'-6"
15'-8"
18'-8"
16'-11"
15'-6"
13'-11"
1000S162-54
22'-1"
20'-0"
18'-10"
17'-6"
20'-0"
18'-2"
17'-2"
15'-11"
1000S162-68
23'-9"
21'-7"
20'-3"
18'-10"
21'-7"
19'-7"
18'-5"
17'-1"
1000S162-97
26'-6"
24'-1"
22'-8"
21'-0"
24'-1"
21'-10"
20'-7"
19'-1"
1200S162-43
23'-9"
20'-10"
19'-0"
16'-8"
21'-5"
18'-6"
16'-6"
13'-2"
1200S162-54
25'-9"
23'-4"
22'-0"
20'-1"
23'-4"
21'-3"
20'-0"
17'-10"
1200S162-68
27'-8"
25'-1"
23'-8"
21'-11"
25'-1"
22'-10"
21'-6"
21'-1"
1200S162-97
30'-11"
28'-1"
26'-5"
24'-6"
28'-1"
25'-6"
24'-0"
22'-3"
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Deflection criteria: L/480 for live loads, L/240 for total loads.
Floor dead load = 10 psf.
Table provides the maximum clear span in feet and inches.
Bearing stiffeners are to be installed at all support points and concentrated loads.
TABLE R505.3.2(2) ALLOWABLE SPANS FOR COLD-FORMED STEEL JOISTS—MULTIPLE SPANSa, b, c, d, e, f 33 ksi STEEL
JOIST DESIGNATION
30 PSF LIVE LOAD
40 PSF LIVE LOAD
Spacing (inches)
Spacing (inches)
12
16
19.2
24
12
16
19.2
24
550S162-33
12'-1"
10'-5"
9'-6"
8'-6"
10'-9"
9'-3"
8'-6"
7'-6"
550S162-43
14'-5"
12'-5"
11'-4"
10'-2"
12'-9"
11'-11"
10'-1"
9'-0"
550S162-54
16'-3"
14'-1"
12'-10"
11'-6"
14'-5"
12'-6"
11'-5"
10'-2"
550S162-68
19'-7"
17'-9"
16'-9"
15'-6"
17'-9"
16'-2"
15'-2"
14'-1"
550S162-97
21'-9"
19'-9"
18'-7"
17'-3"
19'-9"
17'-11"
16'-10"
15'-4"
800S162-33
14'-8"
11'-10"
10'-4"
8'-8"
12'-4"
9'-11"
8'-7"
7'-2"
800S162-43
20'-0"
17'-4"
15'-9"
14'-1"
17'-9"
15'-4"
14'-0"
12'-0"
800S162-54
23'-7"
20'-5"
18'-8"
16'-8"
21'-0"
18'-2"
16'-7"
14'-10"
800S162-68
26'-5"
23'-1"
21'-0"
18'-10"
23'-8"
20'-6"
18'-8"
16'-9"
800S162-97
29'-6"
26'-10"
25'-3"
22'-8"
26'-10"
24'-4"
22'-6"
20'-2"
1000S162-43
22'-2"
18'-3"
16'-0"
13'-7"
18'-11"
15'-5"
13'-6"
11'-5"
1000S162-54
26'-2"
22'-8"
20'-8"
18'-6"
23'-3"
20'-2"
18'-5"
16'-5"
1000S162-68
31'-5"
27'-2"
24'-10"
22'-2"
27'-11"
24'-2"
22'-1"
19'-9"
1000S162-97
35'-6"
32'-3"
29'-11"
26'-9"
32'-3"
29'-2"
26'-7"
23'-9"
1200S162-43
21'-8"
17'-6"
15'-3"
12'-10"
18'-3"
14'-8"
12'-8"
10'-6"
1200S162-54
28'-5"
24'-8"
22'-6"
19'-6"
25'-3"
21'-11"
19'-4"
16'-6"
1200S162-68
33'-7"
29'-1"
26'-6"
23'-9"
29'-10"
25'-10"
23'-7"
21'-1"
1200S162-97
41'-5"
37'-8"
34'-6"
30'-10"
37'-8"
33'-6"
30'-7"
27'-5"
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Deflection criteria: L/480 for live loads, L/240 for total loads.
Floor dead load = 10 psf.
Table provides the maximum clear span in feet and inches to either side of the interior support.
Interior bearing supports for multiple span joists consist of structural (bearing) walls or beams.
Bearing stiffeners are to be installed at all support points and concentrated loads.
Interior supports shall be located within 2 feet of mid-span provided that each of the resulting spans does not exceed the appropriate maximum span shown in the table above.
TABLE R505.3.2(3) ALLOWABLE SPANS FOR COLD-FORMED STEEL JOISTS—MULTIPLE SPANSa, b, c, d, e, f 50 ksi STEEL
JOIST DESIGNATION
30 PSF LIVE LOAD
40 PSF LIVE LOAD
Spacing (inches)
Spacing (inches)
12
16
19.2
24
12
16
19.2
24
550S162-33
13'-11"
12'-0"
11'-0"
9'-3"
12'-3"
10'-8"
9'-7"
8'-4"
550S162-43
16'-3"
14'-1"
12'-10"
11'-6"
14'-6"
12'-6"
11'-5"
10'-3"
550S162-54
18'-2"
16'-6"
15'-4"
13'-8"
16'-6"
14'-11"
13'-7"
12'-2"
550S162-68
19'-6"
17'-9"
16'-8"
15'-6"
17'-9"
16'-1"
15'-2"
14'-0"
550S162-97
21'-9"
19'-9"
18'-6"
17'-2"
19'-8"
17'-10"
16'-8"
15'-8"
800S162-33
15'-6"
12'-6"
10'-10"
9'-1"
13'-0"
10'-5"
8'-11"
6'-9"
800S162-43
22'-0"
19'-1"
17'-5"
15'-0"
19'-7"
16'-11"
14'-10"
12'-8"
800S162-54
24'-6"
22'-4"
20'-6"
17'-11"
22'-5"
19'-9"
17'-11"
15'-10"
800S162-68
26'-6"
24'-1"
22'-8"
21'-0"
24'-1"
21'-10"
20'-7"
19'-2"
800S162-97
29'-9"
26'-8"
25'-2"
23'-5"
26'-8"
24'-3"
22'-11"
21'-4"
1000S162-43
23'-6"
19'-2"
16'-9"
14'-2"
19'-11"
16'-2"
14'-0"
11'-9"
1000S162-54
28'-2"
23'-10"
21'-7"
18'-11"
24'-8"
20'-11"
18'-9"
18'-4"
1000S162-68
31'-10"
28'-11"
27'-2"
25'-3"
28'-11"
26'-3"
24'-9"
22'-9"
1000S162-97
35'-4"
32'-1"
30'-3"
28'-1"
32'-1"
29'-2"
27'-6"
25'-6"
1200S162-43
22'-11"
18'-5"
16'-0"
13'-4"
19'-2"
15'-4"
13'-2"
10'-6"
1200S162-54
32'-8"
28'-1"
24'-9"
21'-2"
29'-0"
23'-10"
20'-11"
17'-9"
1200S162-68
37'-1"
32'-5"
29'-4"
25'-10"
33'-4"
28'-6"
25'-9"
22'-7"
1200S162-97
41'-2"
37'-6"
35'-3"
32'-9"
37'-6"
34'-1"
32'-1"
29'-9"
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Deflection criteria: L/480 for live loads, L/240 for total loads.
Floor dead load = 10 psf.
Table provides the maximum clear span in feet and inches to either side of the interior support.
Interior bearing supports for multiple span joists consist of structural (bearing) walls or beams.
Bearing stiffeners are to be installed at all support points and concentrated loads.
Interior supports shall be located within 2 feet of mid-span provided that each of the resulting spans does not exceed the appropriate maximum span shown in the table above.
The top flanges of cold-formed steel joists shall be laterally braced by the application of floor sheathing fastened to the joists in accordance with Section R505.2.4 and Table R505.3.1(2).
Floor joists with spans that exceed 12 feet (3658 mm) shall have the bottom flanges laterally braced in accordance with one of the following:
Gypsum board installed with minimum No. 6 screws in accordance with Section R702.
Continuous steel straps installed in accordance with Figure R505.3.3.2(1). Steel straps shall be spaced at a maximum of 12 feet (3658 mm) on center and shall be at least 11/2 inches (38 mm) in width and 33 mils (0.84 mm) in thickness. Straps shall be fastened to the bottom flange of each joist with one No. 8 screw, fastened to blocking with two No. 8 screws, and fastened at each end (of strap) with two No. 8 screws. Blocking in accordance with Figure R505.3.3.2(1) or Figure R505.3.3.2(2) shall be installed between joists at each end of the continuous strapping and at a maximum spacing of 12 feet (3658 mm) measured along the continuous strapping (perpendicular to the joist run). Blocking shall also be located at the termination of all straps. As an alternative to blocking at the ends, anchoring the strap to a stable building component with two No. 8 screws shall be permitted.
Blocking is not required for continuous back-to-back floor joists at bearing supports. Blocking shall be installed between every other joist for single continuous floor joists across bearing supports in accordance with Figure R505.3.1(7). Blocking shall consist of C-shape or track section with a minimum thickness of 33 mils (0.84 mm). Blocking shall be fastened to each adjacent joist through a 33-mil (0.84 mm) clip angle, bent web of blocking or flanges of web stiffeners with two No. 8 screws on each side. The minimum depth of the blocking shall be equal to the depth of the joist minus 2 inches (51 mm). The minimum length of the angle shall be equal to the depth of the joist minus 2 inches (51 mm).
Blocking shall be installed between every other joist over cantilever bearing supports in accordance with Figure R505.3.1(4), R505.3.1(5) or R505.3.1(6). Blocking shall consist of C-shape or track section with minimum thickness of 33 mils (0.84 mm). Blocking shall be fastened to each adjacent joist through bent web of blocking, 33 mil clip angle or flange of web stiffener with two No. 8 screws at each end. The depth of the blocking shall be equal to the depth of the joist. The minimum length of the angle shall be equal to the depth of the joist minus 2 inches (51 mm). Blocking shall be fastened through the floor sheathing and to the support with three No. 8 screws (top and bottom).
Bearing stiffeners shall be installed at each joist bearing location in accordance with this section, except for joists lapped over an interior support not carrying a load-bearing wall above. Floor joists supporting jamb studs with multiple members shall have two bearing stiffeners in accordance with Figure R505.3.4(1). Bearing stiffeners shall be fabricated from a C-shaped, track or clip angle member in accordance with the one of following:
C-shaped bearing stiffeners:
Where the joist is not carrying a load-bearing wall above, the bearing stiffener shall be a minimum 33 mil (0.84 mm) thickness.
Where the joist is carrying a load-bearing wall above, the bearing stiffener shall be at least the same designation thickness as the wall stud above.
Track bearing stiffeners:
Where the joist is not carrying a load-bearing wall above, the bearing stiffener shall be a minimum 43 mil (1.09 mm) thickness.
Where the joist is carrying a load-bearing wall above, the bearing stiffener shall be at least one designation thickness greater than the wall stud above.
Clip angle bearing stiffeners: Where the clip angle bearing stiffener is fastened to both the web of the member it is stiffening and an adjacent rim track using the fastener pattern shown in Figure R505.3.4(2), the bearing stiffener shall be a minimum 2 inch by 2 inch (51 mm by 51 mm) angle sized in accordance with Tables R505.3.4(1), R505.3.4(2), R505.3.4(3), and R505.3.4(4).
The minimum length of a bearing stiffener shall be the depth of member being stiffened minus 3/8 inch (9.5 mm). Each bearing stiffener shall be fastened to the web of the member it is stiffening as shown in Figure R505.3.4(2). Each clip angle bearing stiffener shall also be fastened to the web of the adjacent rim track using the fastener pattern shown in Figure R505.3.4(2). No. 8 screws shall be used for C-shaped and track members of any thickness and for clip angle members with a designation thickness less than or equal to 54. No. 10 screws shall be used for clip angle members with a designation thickness greater than 54.
Floor cantilevers for the top floor of a two- or three-story building or the first floor of a one-story building shall not exceed 24 inches (610 mm). Cantilevers, not exceeding 24 inches (610 mm) and supporting two stories and roof (i.e., first floor of a two-story building), shall also be permitted provided that all cantilevered joists are doubled (nested or back-to-back). The doubled cantilevered joists shall extend a minimum of 6 feet (1829 mm) toward the inside and shall be fastened with a minimum of two No. 8 screws spaced at 24 inches (610 mm) on center through the webs (for back-to-back) or flanges (for nested joists).
Openings in floors shall be framed with header and trimmer joists. Header joist spans shall not exceed 6 feet (1829 mm) or 8 feet (2438 mm) in length in accordance with Figure R505.3.8(1) or R505.3.8(2), respectively. Header and trimmer joists shall be fabricated from joist and track members, having a minimum size and thickness at least equivalent to the adjacent floor joists and shall be installed in accordance with Figures R505.3.8(1), R505.3.8(2), R505.3.8(3), and R505.3.8(4). Each header joist shall be connected to trimmer joists with four 2 inch by 2 inch (51 mm by 51 mm) clip angles. Each clip angle shall be fastened to both the header and trimmer joists with four No. 8 screws, evenly spaced, through each leg of the clip angle. The clip angles shall have a thickness not less than that of the floor joist. Each track section for a built-up header or trimmer joist shall extend the full length of the joist (continuous). FIGURE R505.3.8(1) COLD-FORMED STEEL FLOOR CONSTRUCTION: 6-FOOT FLOOR OPENING
Concrete slab-on-ground floors shall be designed and constructed in accordance with the provisions of this section or ACI 332. Floors shall be a minimum 3.5 inches (89 mm) thick (for expansive soils, see Section R403.1.8). The specified compressive strength of concrete shall be as set forth in Section R402.2.
Fill material shall be free of vegetation and foreign material. The fill shall be compacted to assure uniform support of the slab, and except where approved, the fill depths shall not exceed 24 inches (610 mm) for clean sand or gravel and 8 inches (203 mm) for earth.
A 4-inch-thick (102 mm) base course consisting of clean graded sand, gravel, crushed stone or crushed blast-furnace slag passing a 2-inch (51 mm) sieve shall be placed on the prepared subgrade when the slab is below grade.
Exception: A base course is not required when the concrete slab is installed on well-drained or sand-gravel mixture soils classified as Group I according to the United Soil Classification System in accordance with Table R405.1.
A 6-mil (0.006 inch; 152 µm) polyethylene or approvedvapor retarder with joints lapped not less than 6 inches (152 mm) shall be placed between the concrete floor slab and the base course or the prepared subgrade where no base course exists.
Where provided in slabs on ground, reinforcement shall be supported to remain in place from the center to upper one third of the slab for the duration of the concrete placement.
Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. For decks with cantilevered framing members, connections to exterior walls or other framing members, shall be designed and constructed to resist uplift resulting from the full live load specified in Table R301.5 acting on the cantilevered portion of the deck.
For decks supporting a total design load of 50 pounds per square foot (2394 Pa) [40 pounds per square foot (1915 Pa) live load plus 10 pounds per square foot (479 Pa) dead load], the connection between a deck ledger of pressure-preservative-treated Southern Pine, incised pressure-preservative-treated Hem-Fir or approveddecay-resistant species, and a 2-inch (51 mm) nominal lumber band joist bearing on a sill plate or wall plate shall be constructed with 1/2-inch (12.7 mm) lag screws or bolts with washers in accordance with Table R507.2. Lag screws, bolts and washers shall be hot-dipped galvanized or stainless steel.
TABLE R507.2 FASTENER SPACING FOR A SOUTHERN PINE OR HEM-FIR DECK LEDGER AND A 2-INCH-NOMINAL SOLID-SAWN SPRUCE-PINE-FIR BAND JOISTc, f, g (Deck live load = 40 psf, deck dead load = 10 psf)
JOIST SPAN
6' and less
6'1" to 8'
8'1" to 10'
10'1" to 12'
12'1" to 14'
14'1" to 16'
16'1" to 18'
Connection details
On-center spacing of fastenersd, e
1/2 inch diameter lag screw with 15/32 inch maximum sheathinga
30
23
18
15
13
11
10
1/2 inch diameter bolt with 15/32 inch maximum sheathing
36
36
34
29
24
21
19
1/2 inch diameter bolt with 15/32 inch maximum sheathing and 1/2 inch stacked washersb, h
36
36
29
24
21
18
16
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. 1 pound per square foot = 0.0479 kPa.
The tip of the lag screw shall fully extend beyond the inside face of the band joist.
The maximum gap between the face of the ledger board and face of the wall sheathing shall be 1/2 inch.
Ledgers shall be flashed to prevent water from contacting the house band joist.
Lag screws and bolts shall be staggered in accordance with Section R507.2.1.
Deck ledger shall be minimum 2 × 8 pressure-preservative-treated No. 2 grade lumber, or other approved materials as established by standard engineering practice.
A minimum 1 × 91/2 Douglas Fir laminated veneer lumber rimboard shall be permitted in lieu of the 2-inch nominal band joist.
Wood structural panel sheathing, gypsum board sheathing or foam sheathing not exceeding 1 inch in thickness shall be permitted. The maximum distance between the face of the ledger board and the face of the band joist shall be 1 inch.
Deck ledger connections not conforming to Table R507.2 shall be designed in accordance with accepted engineering practice. Girders supporting deck joists shall not be supported on deck ledgers or band joists. Deck ledgers shall not be supported on stone or masonry veneer.
The lateral load connection required by Section R507.1 shall be permitted to be in accordance with Figure R507.2.3. Where the lateral load connection is provided in accordance with Figure 507.2.3, hold-down tension devices shall be installed in not less than two locations per deck, and each device shall have an allowable stress design capacity of not less than 1500 pounds (6672 N). FIGURE 507.2.3 DECK ATTACHMENT FOR LATERAL LOADS
Wood/plastic composites used in exterior deck boards, stair treads, handrails and guardrail systems shall bear a label indicating the required performance levels and demonstrating compliance with the provisions of ASTM D 7032.
