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MyBuf ldi ngPermit.cam <br /> a service of eCityGov.net Construction Tip Sheet 05 <br /> Sizing of Structural Elements <br /> When using the tables below, interpolation is allowed (but extrapolation is not allowed). <br /> Maximum Deck Joist Span a,e <br /> Joist Spacing (inches)b Joist Back Span (feet) <br /> Joist <br /> Size 12 16 ( 24 ) 4 6 8 10 12 14 16 _ 18 <br /> Allowable Joist Span d Maximum Cantilever(feet-inches)d <br /> 2x6 7-11 7-1 5-9) 1-0 1-6 NP NP NP NP NP NP <br /> 2x8 10-5 9-5 7-8 1-0 1-6 2-0 2-1 NP NP NP NP <br /> 2x 10 13-3 11-6 9-5 1-0 1-6 2-0 2-6 2-8 NP NP NP <br /> 2x12 15-5 13-4 10-11 1-0 1-6 2-0 2-6 3-0 3-3 NP NP <br /> NP = Not Permitted <br /> a. Includes Incising Factor. <br /> b. When using composite decking, refer to manufacturer's installation instructions for maximum spacing <br /> of joists. <br /> c. Spans based on Doug Fir-Larch, Hem Fir and Spruce-Pine-Fir, Number 2 grade, wet service factor. <br /> d. For fire-retardant-treated wood (exterior grade), follow the manufacturer's span tables. <br /> Minimum Beam Size <br /> Deck Joist Span (feet) <br /> 6 ) 8 10 12 14 16 18 <br /> Beam Size a.d.e,r a'b.d,f <br /> Maximum Beam Span (feet-inches) <br /> 4x6 ( 5-2 ') 4-6 4-0 3-5 3-1 2-10 2-7 <br /> 4x8 6-11 6-0 5-3 4-7 4-1 3-8 3-5 <br /> 4x10 8-5 7-4 6-6 5-10 5-2 4-9 4-5 <br /> 4x12 9-10 8-6 7-7 6-11 6-4 5-9 5-4 <br /> 6x6 6-6 5-7 5-0 4-7 4-2 3-9 3-5 <br /> 6x8 8-8 7-6 6-8 6-1 5-6 5-0 4-7 <br /> 6x10 10-7 9-2 8-2 7-6 6-11 6-4 5-10 <br /> 6x12 12-4 10-8 9-7 8-9 8-1 7-7 7-1 <br /> a. Spans based on Doug Fir-Larch, Hem Fir and Spruce-Pine-Fir, Number 2 grade, wet service factor. <br /> b. If 2x built up beams to make 4x or 6x beams, they shall be fastened with two rows of 10d (3-inch x <br /> 0.128-inch) nails minimum at 16 inches on center along each edge (R507.5). <br /> c. Beam depth shall be equal to or greater than the depth of intersecting joist for a flush <br /> beam connection. <br /> d. Beam cantilevers are limited to the adjacent beam's span divided by 4. <br /> e. Includes incising factor. <br /> f. For fire-retardant-treated wood (exterior grade), follow the manufacturer's span tables. <br /> May 29,2024 MyBuildingPermit.com I Basic Deck 3 <br /> .'eCityGov.net <br /> 2C05.F eCkyGcti•A6encw <br />