Garage Roof Timber Sizes

Surveyors span tables for designing roof rafters.

Garage roof timber sizes.

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. 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. For pitched roofs flat roofs and ceiling joists. This sizing guide for roof rafters will help determine what you need for your small project.

This is the distance between joist centres. 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. Garage roof sheets are made from a variety of materials and each material comes with its own benefits so it is important to select the best one for your garage roof. 125mm x 16mm nominal size high quality scandinavian redwood tongue and groove boards.

The joists will normally be placed at 400mm centres but no more than 600mm centres. Wherever possible joists should span the shortest distance. Common joists sizes are 200 x 50mm 175 x 50mm and 150 x 50mm. 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.

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. The sizing and spacing will depend upon the loads imposed on them and the required span.