Timber Roof Truss Span Tables

Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.

Timber roof truss span tables.

Spacing of trusses are center to center in inches. Center line chase 24 max. A maximum roof pitch of 25 degrees is assumed. Bottom chord dead load 5 psf.

Trusses must be designed for any special loading such as concentrated loads. View allowable load tables. An added benefit are the strong lines that purlins create by running parallel to the ridge beam s. Required size for a given span.

Adding purlins between heavy timber trusses is an elegant way to reduce the cost of a timber frame roof because purlins permit an increased on center distance between trusses so you purchase fewer trusses. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3. View joist rafter tables. Other more complex load condition spans can be determined with our free hyne timber design 7 5 software.

Construction details should be in accordance with as1684 2. View size selection tables. Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope. Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.

Spacing should be interpreted as the centre to centre distance between adjacent parallel members. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.

Timber frame truss and purlins.