Flat Roof Joist Sizes Uk

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

Flat roof joist sizes uk.

Although flat roofs are cheaper to build than pitched roofs they have a shorter life span. Supporting imposed load. Flat roof joist calculator. The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof.

2011 control of condensation in buildings is the document to view. For pitched roofs flat roofs and ceiling joists. Enter a specific joist size 2 loadings. Flat roof construction for residential.

More common timber sizes used in flat roof construction. Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support. They are nailed securely to exterior wall plates and to each other. This air is vented at either end of the roof to allow a continuous air flow.

All the figures are based on the normal loading conditions. 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. Flat roof with asphalt finish with felt. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal. In terms of rules on ventilation bs 5250. The rafters in a flat roof serve as ceiling joists for the space below. Surveyors span tables for designing roof rafters.

All figures are based on. Automatically calculate sizes suitable for supporting the loads below or. 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. A flat roof usually consists of the following.

Waterproof membrane to prevent water penetrating the structure and interior of the. Subject ceilings and flat roofs timber sizes and construction details 09 issued 01 04 13 rev page 1 of 2 the following tables give details of the allowable spans and spacing for some of the more common timber sizes used in ceiling and flat roof construction. Solid timber joist sizes are provided in the bs 8103 3 span tables.