Garage Roof Timber Sizes

This sizing guide for roof rafters will help determine what you need for your small project.

Garage roof timber sizes.

Surveyors span tables for designing roof rafters. There are several variables to consider when determining the proper rafter size. The sizing and spacing will depend upon the loads imposed on them and the required span. We use 100mm x 38mm framework which run top to bottom in the roof rather than the purling effect which has a higher likelihood of twisting then we support these with 100mm x 38mm trusses.

Metal roof sheets metal garage roof sheets are popular due to their ability to withstand extreme weather conditions affordability and ability to withstand high temperatures. Size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41 75 x 170 4 50. Usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below. Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.

Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. Common joists sizes are 200 x 50mm 175 x 50mm and 150 x 50mm. 125mm x 16mm nominal size high quality scandinavian redwood tongue and groove boards. For pitched roofs flat roofs and ceiling joists.

They also tell you what the maximum spacing should be between each section or timber member size of joists mm clear span c16 joist m clear span c24 joist m 47 x 95 47 x 120 47 x 145 47 x 170 47 x 195 47 x 220 1 77 2 40 2 89 3 38 3 87 4 36 2 05 2 67 3 22 3 77 4 31 4 85 assumptions at 400mm centers. Wherever possible joists should span the shortest distance.