Top chord dead load 10 psf.
Timber roof truss span tables.
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.
Required size for a given span.
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.
Spacing of trusses are center to center in inches.
Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.
Timber frame truss and purlins.
Spacing should be interpreted as the centre to centre distance between adjacent parallel members.
An added benefit are the strong lines that purlins create by running parallel to the ridge beam s.
View size selection tables.
View joist rafter tables.
Bottom chord dead load 5 psf.
For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.
A maximum roof pitch of 25 degrees is assumed.
Center line chase 24 max.
Construction details should be in accordance with as1684 2.
Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70.
Trusses must be designed for any special loading such as concentrated loads.
Other more complex load condition spans can be determined with our free hyne timber design 7 5 software.
Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.
Technical diagram span tables f7 rafters on page 35 30mm m aximum allow able sp ans mm sheet roof spacing mm rafter size 600 760 900 1000 1200 66 x 30 1250 1150 1050 1000 950 90 x 30 1650.
Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.
