2304.8 Floor and roof sheathing.
BC § 2304.8
Structural floor sheathing and structural roof sheathing shall comply with Sections 2304.8.1 and 2304.8.2, respectively. Table 2304.8(1)Allowable Spans for Lumber Floor and Roof Sheathing Span (inches)Minimum Net Thickness (inches) of Lumber PlacedPerpendicular to supportsDiagonally to supportsSurfaced dry aSurfaced unseasonedSurfaced dry aSurfaced unseasonedSpan (inches)Minimum Net Thickness (inches) of Lumber PlacedPerpendicular to supportsDiagonally to supportsSurfaced dry aSurfaced unseasonedSurfaced dry aSurfaced unseasonedFloors243/425/323/425/32165/811/165/811/16Roofs245/811/163/425/32 For SI: 1 inch = 25.4 mm. a. Maximum 19-percent moisture content. Table 2304.8(2)Sheathing Lumber, Minimum Grade Requirements: Board Grade Solid Floor or Roof SheathingSpaced Roof SheathingGrading RulesUtilityStandardNLGA, WCLIB, WWPA4 common or utility 3 common or standardNLGA, WCLIB, WWPA, NSLB or NELMA No. 3No. 2SPIBMerchantableConstruction commonRIS Table 2304.8(3)Allowable Spans and Loads for Wood Structural Panel Sheathing and Single-Floor Grades Continuous over Two or More Spans with Strength Axis Perpendicular to Supports a Sheathing GradesRoof bFloor cPanel span rating roof / floor spanPanel thickness(inches)Maximum span (inches)Load d (psf)Maximum span(inches)With edge support eWithout edge supportTotal loadLive load16/03/816164030020/03/820204030024/03/8, 7/16, 1/22420 f4030024/167/16, 1/2242450401632/1615/32, 1/2, 5/83228403016 g40/2019/32, 5/8, 3/4, 7/84032403020 g, h48/2423/32, 3/4, 7/8483645352454/327/8, 1544045353260/327/8, 1 1/86048453532Single Floor GradesRoof bFloor cPanel span ratingPanel thickness(inches)Maximum span (inches)Load d (psf)Maximum span(inches)With edge support eWithout edge supportTotal loadLive load16 o.c.1/2, 19/32, 5/82424504016 g20 o.c.19/32, 5/8, 3/43232403020 g, h24 o.c.23/32, 3/4483635252432 o.c.7/8, 1484050403248 o.c.1 3/32, 1 1/86048504048 For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kN/m 2 . a. Applies to panels 24 inches or wider. b. Uniform load deflection limitations 1/180 of span under live load plus dead load, 1/240 under live load only. c. Panel edges shall have approved tongue-and-groove joints or shall be supported with blocking unless 1/4-inch minimum thickness underlayment or 1 1/2 inches of approved cellular or lightweight concrete is placed over the subfloor, or finish floor is 3/4-inch wood strip. Allowable uniform load based on deflection of 1/360 of span is 100 pounds per square foot except the span rating of 48 inches on center is based on a total load of 65 pounds per square foot. d. Allowable load at maximum span. e. Tongue-and-groove edges, panel edge clips (one midway between each support, except two equally spaced between supports 48 inches on center), lumber blocking or other. Only lumber blocking shall satisfy blocked diaphragm requirements. f. For 1/2-inch panel, maximum span shall be 24 inches. g. Span is permitted to be 24 inches on center where 3/4-inch wood strip flooring is installed at right angles to joist. h. Span is permitted to be 24 inches on center for floors where 1 1/2 inches of cellular or lightweight concrete is applied over the panels. Table 2304.8(4)Allowable Span for Wood Structural Panel Combination Subfloor-Underlayment (Single Floor), a(Panels Continuous Over Two or More Spans and Strength Axis Perpendicular to Supports) IdentificationMaximum Spacing of Joists (inches)1620243248Species group bThickness (inches)11/25/83/4——2, 35/83/47/8——43/47/81——Single floor span rating c16 o.c.20 o.c.24 o.c.32 o.c.48 o.c. For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kN/m 2 . a. Spans limited to value shown because of possible effects of concentrated loads. Allowable uniform loads based on deflection of 1/360 of span is 100 pounds per square foot except allowable total uniform load for 1 1/8-inch wood structural panels over joists spaced 48 inches on center is 65 pounds per square foot. Panel edges shall have approved tongue-and-groove joints or shall be supported with blocking, unless 1/4-inch minimum thickness underlayment or 1 1/2 inches of approved cellular or lightweight concrete is placed over the subfloor, or finish floor is 3/4-inch wood strip. b. Applicable to all grades of sanded exterior-type plywood. See DOC PS 1 for plywood species groups. c. Applicable to Underlayment grade, C-C (Plugged) plywood, and Single Floor grade wood structural panels. Table 2304.8(5)Allowable Load (psf) for Wood Structural Panel Roof Sheathing Continuous over Two or More Spans and Strength Axis Parallel to Supports(Plywood Structural Panels Are Five-Ply, Five-Layer Unless Otherwise Noted) a Panel GradeThickness(inch)Maximum Span (inches)Load at Maximum Span (psf)LiveTotalPanel GradeThickness(inch)Maximum Span (inches)Load at Maximum Span (psf)LiveTotalStructural I sheathing 7/1624203015/322435 b45 b1/22440 b50 b19/32, 5/824708023/32, 3/42490100Sheathing, other grades covered in DOC PS 1 or DOC PS 27/1616405015/322420251/224253019/322440 b50 b5/82445 b55 b23/32, 3/42460 b65 b For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kN/m 2 . a. Uniform load deflection limitations 1/180 of span under live load plus dead load, 1/240 under live load only. Edges shall be blocked with lumber or other approved type of edge supports. b. For composite and four-ply plywood structural panel, load shall be reduced by 15 pounds per square foot.
