Standard tables have been developed for sizing repetitive members International Residential Code (IRC) Major lumber associations American Forest and Paper Association Western Wood Products Association Southern Forest Products AssociationĬommon types of framing lumber Douglas fir–larch (DFL #2) Southern pine (SP #2) Spruce-pine-fir (SPF #2) Hemlock-fir (Hem-fir #2) 1 Sizing Joists and Rafters using Span TablesĬhapter 30 Sizing Joists and Rafters using Span TablesĢ Introduction Structure complexity and drafter experience determines who sizes framing members Even if determined by an engineer, drafter should understand how span tables are used Standard framing practice is to place structural members at 12', 16', 19.2', or 24' on center
