Flat Roof Timber Sizes

Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.

Flat roof timber sizes.

Where a new flat roof abuts an existing external wall the joists can be hung on metal joist hangers which are fixed to a horizontal timber plate wall bolted to the wall. Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load. Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists 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. For pitched roofs flat roofs and ceiling joists.

Supporting imposed load. Flat roof joists. Structural calculations for timber joists timber beams glulam beams flitch beams using the latest design codes. Surveyors span tables for designing roof rafters.

This sizing guide for roof rafters will help determine what you need for your small project. These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Here the number is 941 86 inches. A cavity closer should be provided to the top of the walls to prevent fire spread and to stop damp air entering the roof space.

Flat roofs timber sizes and construction. Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall. Calculations to bs 5268 2. 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. Automatically calculate suitable rafter sizes enter a specific rafter size. There are several variables to consider when determining the proper rafter size. 2002 bs 5268 7 5.

Here the number is 1166 66 inches.