Flat Garage Roof Timber Sizes

Supporting imposed load for access and repair only.

Flat garage roof timber sizes.

Wherever possible joists should span the shortest distance. 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. 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. 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 04 2 75 3 47 4 20 4 93 5 66 floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.

The sizing and spacing will depend upon the loads imposed on them and the required span. The joists will normally be placed at 400mm centres but no more than 600mm centres. Completely flat roofs typically present weather proofing problems so the rafters or joists of some flat roofs are laid at a slight angle for drainage. If this is the case the slope of the.

Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. There are several variables to consider when determining the proper rafter size. This sizing guide for roof rafters will help determine what you need for your small project.