Timber Roof Beam Sizes

Per wwpa guidelines for standard dimension timbers a nominal 4 x6 timber nets to 3 x5 actual dimensions after it has been sawn all beams larger than 8 inch will mill to the inch.

Timber roof beam sizes.

For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3. These tables are provided as a guideline. Click on a span to generate a full calculation you can adjust the exact span. Aitc beam capacity tables.

In the example d calculates to 7 75. A 8x12 beam will net an overall 7 x 11. Stress grades and timber sizes combine to determine the spanning ability of load carrying members. This tells you the size of the beam needed to support the porch s roof.

Starting from scratch with no previous knowledge of structures required. Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs. This span table is to the format and methodology given in bs 5268 7 2. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.

Table specifications are provided with each table indicating conditions and assumptions used to calculate the loads. This means the example porch would need a 6 inch by 8 inch beam. Aitc capacity tables provide the uniformly distributed load that a glued laminated timber beam can support based on beam size span and material properties. Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres.

All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. These spans were calculated using our flat roof joist calculation. This calculator matches up with 90 of the applications in the 2012 international residential code book. Designing with roof rafter span tables lvl 2 0e 2900fb power beam anthony forest s co raising ceiling joists jlc roofdek manual structural roof decking and trays.

Our heavy timber beams are cut to standard dimensions. 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below c16 cost effective for most applications c24 stronger more demanding c14 c18 c22 c27 c30 c35 c40. Calculate the initial value for d then round it up to the nearest inch. Here s how to calculate the size of a timber beam you need to span a given distance.

Pitched roof timber sizes.