SPAN TABLES FOR JOISTS AND RAFTERS

1 American Wood CouncilSPAN TABLES FORJOISTS AND RAFTERS2005 EDITIONA mericanForest &PaperAssociationAmerican Softwood LumberStandard (PS 20-05) SizesThe American Wood Council (AWC) is the wood products division of the AmericanForest & Paper Association (AF&PA). AF&PA is the national trade association of theforest, paper, and wood products industry, representing member companies engagedin growing, harvesting, and processing wood and wood fiber, manufacturing pulp,paper, and paperboard products from both virgin and recycled fiber, and producingengineered and traditional wood products. For more information see every effort has been made to insure the accuracyof the information presented, and special effort has beenmade to assure that the information reflects the state-of-the-art, neither the American Forest & Paper Associationnor its members assume any responsibility for anyparticular design prepared from this publication.

2 Thoseusing this document assume all liability from its 1993, 2006 American Forest & Paper Association, Wood Council1111 19th St., NW, Suite 800 Washington, DC TABLES FORJOISTS AND RAFTERS2005 EDITIONTABLE OF of TablesPageExplanation of JOISTS WITH L/360 DEFLECTION LIMITSF-1 Live Load of 30 psf plus dead load of 10 psf ..4F-2 Live Load of 40 psf plus dead load of 10 psf ..5F-3 Live Load of 50 psf plus dead load of 10 psf ..6F-4 Live Load of 60 psf plus dead load of 10 psf ..7F-5 Live Load of 40 psf plus dead load of 20 psf ..8F-6 Live Load of 50 psf plus dead load of 20 psf ..9F-7 Live Load of 60 psf plus dead load of 20 psf ..10 CEILING JOISTS WITH L/240 DEFLECTION LIMITSC-1 Live Load of 10 psf plus dead load of 5 psf.

3 11C-2 Live Load of 20 psf plus dead load of 10 psf ..12 RAFTERS WITH L/240 DEFLECTION LIMITSR-1 Live Load of 20 psf plus dead load of 10 psf ..13R-2 Live Load of 30 psf plus dead load of 10 psf ..14R-3 Live Load of 40 psf plus dead load of 10 psf ..15R-4 Live Load of 50 psf plus dead load of 10 psf ..16R-5 Live Load of 20 psf plus dead load of 15 psf ..17R-6 Live Load of 30 psf plus dead load of 15 psf ..18R-7 Live Load of 40 psf plus dead load of 15 psf ..19R-8 Live Load of 50 psf plus dead load of 15 psf ..20R-9 Live Load of 20 psf plus dead load of 20 psf ..21R-10 Live Load of 30 psf plus dead load of 20 psf ..22R-11 Live Load of 40 psf plus dead load of 20 psf.

4 23R-12 Live Load of 50 psf plus dead load of 20 psf ..24 RAFTERS WITH L/180 DEFLECTION LIMITSR-13 Live Load of 20 psf plus dead load of 10 psf ..25R-14 Live Load of 30 psf plus dead load of 10 psf ..26R-15 Live Load of 40 psf plus dead load of 10 psf ..27R-16 Live Load of 50 psf plus dead load of 10 psf ..28R-17 Live Load of 20 psf plus dead load of 15 psf ..29R-18 Live Load of 30 psf plus dead load of 15 psf ..30R-19 Live Load of 40 psf plus dead load of 15 psf ..31R-20 Live Load of 50 psf plus dead load of 15 psf ..32R-21 Live Load of 20 psf plus dead load of 20 psf ..33R-22 Live Load of 30 psf plus dead load of 20 psf ..34R-23 Live Load of 40 psf plus dead load of 20 psf.

5 35R-24 Live Load of 50 psf plus dead load of 20 psf .. A-1 SPAN TABLES FOR JOISTS AND RAFTERS1 AMERICAN FOREST & PAPER ASSOCIATIONEXPLANATION OF span TABLES for JOISTS and RAFTERS are calcu-lated on the basis of a series of modulus of elasticity (E)and bending design values (Fb). Additionally, compres-sion perpendicular to grain design values (Fc ) areincluded as a consideration for selection of JOISTS andrafters. The range of values in the TABLES providesallowable spans for all species and grades of nominal 2-inch framing lumber customarily used in span TABLES assume installation of at least threejoists or RAFTERS that are spaced not more than 24" oncenter.

6 The calculated spans assume fully supportedmembers, properly sheathed and nailed on the top edgeof the joist or rafter. Straight-line interpolation shall bepermitted for intermediate spans and design design VALUESUse of these span TABLES requires reference to theapplicable design values for the various species andgrades of lumber. TABLES W-1 and W-2 of DesignValues for JOISTS and RAFTERS , a supplement to thesespan TABLES , provide such values for the most commonlyused framing sizes. Modulus of elasticity (E), bendingdesign values (Fb), and compression design valuesperpendicular to grain (Fc ) therein are based on theNational design Specification (NDS ) for WoodConstruction and incorporate adjustments appropriatefor repetitive-member use under various durations SIZEST abulated spans apply to surfaced (S4S) lumberhaving dimensions which conform to the AmericanSoftwood Lumber Standard, PS 20-05.

7 These sizes areas follows:NominalActual SurfacedSizeDry Size2 x 41-1/2 x 3-1/22 x 61-1/2 x 5-1/22 x 81-1/2 x 7-1/42 x 101-1/2 x 9-1/42 x 121-1/2 x 11-1 CONTENTThe listed dry sizes are based on lumber at 19percent maximum moisture content. Since the changein dimension that occurs in wet service conditions hasalready been accounted for in the fully adjusted designvalue, tabulated spans are applicable to lumber in dry orwet service MEASUREMENTT abulated spans are the distance from face to faceof supports. For sloping RAFTERS the span is measuredalong the horizontal projection. The commentary pro-vides further information on span measurements in-cluding a chart which converts horizontal distances tosloping distances, or vice LOADSR after spans are tabulated for the most commonroof loads.

8 The loads are based on adjusted roof snowloads from the governing building code. For roof liveloads less than 20 pounds per square foot (psf), rafterspans and required E values tabulated for 20 psf shall bepermitted to be adjusted in accordance with the follow-ing table:For roof live loads of 12 psf or 16 psfTableMultiply tabulatedMultiply requirednumberspan byE- value by12 psf16 psf12 psf16 intermediate values of roof live loads, use straight OF TABLESAMERICAN WOOD IDENTIFICATIONThe tabulated spans in these TABLES apply to lum-ber identified by the grade stamp of, or certificate ofinspection issued by, a lumber grading or inspectionbureau or agency recognized as being competent by theBoard of Review of the American Lumber StandardCommittee or the Canadian Lumber Standards Ac-creditation REQUIREMENTSThe quality of wood products and fasteners andthe design of load-supporting members and connec-tions shall conform to the NDS.

9 All members shall be soframed, anchored, tied, and braced that they have thenecessary strength and rigidity. Adequate bracing andbridging to resist wind and other lateral forces shall COMPRESSIONPERPENDICULAR TO GRAINThe required compression perpendicular to graindesign value , Fc , for the joist or rafter shall be deter-mined from Table The table assumes a total load plf on the joist or rafter. The required Fc valueshall be permitted to be adjusted in direct proportion toalternate total loads using factors tabulated in Table commentary outlines several examples that includeprovisions for determining required compression per-pendicular to grain design TABLES FOR JOISTS AND RAFTERS3 AMERICAN FOREST & PAPER ASSOCIATIONT able compression perpendicular to grain design values (Fc ) in pounds per square inch forsimple span JOISTS and RAFTERS with uniform Length, , : 1) Bearing width is assumed to be ".

10 2) Total uniform load is assumed to be ) Alternate Fc values are possible by adjusting the tabulated values in direct proportion to the desiredload. Adjustment factors are tabulated in Table ) See for 2 span floor joist factors for alternate loading and spacing conditions for determining requiredcompression perpendicular to grain design values (Fc ) for JOISTS and , psfOn-center spacing, :Multiply Table values by adjustment factors to obtain required compression perpendicularto grain design Span TABLES for JOISTS and RaftersAmerican Wood CouncilDESIGN CRITERIA:Deflection - For 30 psf live to span in inches divided by - Live load of 30 psf plus dead loadof 10 psf determines the required bending design - 49 - 910 - 110 - 510 - 911 - 011 - 311 - 711 - 1012 - 012 - 312 - 612 - 912 - 1113 - 113 - 413 - - 68 - 109 - 29 - 69 - 910 - 010 - 310 - 610 - 910 - 1111 - 211 - 411 - 711 - 911 - 1112 - 112 - - 08 - 48 - 88 - 119 - 29 - 59 - 89 - 1010 - 110 - 410 - 610 - 810 - 1011 - 111 - 311 - 511 - - 57 - 98 - 08 - 38 - 68 - 98 - 119 - 29 - 49 - 79 - 99 - 1110 - 110 - 310 - 510 - 710 - - 412 - 1013 - 413 - 914 - 214 - 614 - 1115 - 315 - 715 - 1016 - 216 - 616 - 917 - 017 - 417 - 717 - - 311 - 812 - 112 - 612 - 1013.