Roof Timber Sizes And Spans

In any other situation you should refer to trada document span tables for solid timber members in floors.

Roof timber sizes and spans.

All figures are based on normal loading conditions found in domestic construction. 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. Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. For pitched roofs flat roofs and ceiling joists. Pitched roof timber sizes. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.

The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction. This span table is to the format and methodology given in bs 5268 7 2. Click on a span to generate a full calculation you can adjust the exact span. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.

These spans were calculated using our flat roof joist calculation.