Timber Roof Joist Span Tables Uk

This is the distance between joist centres.

Timber roof joist span tables uk.

Span tables for solid timber joists. 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. 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. The weight of the timber floor itself consists of the timber joists the plasterboard ceiling underneath it except for suspended timber ground floors the floorboards and the nails or screws used to fix both of the aforementioned coverings.

Usually 400 450 or 600mm but any value can be used up to 610mm max usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size. Solid timber strutting to be at least 38mm thick and be a minimum of three quarters of the joist depth. Surveyors span tables for designing roof rafters. Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3.

Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. For spans of between 2 5 and 4 5 m one row of strutting is needed at the mid span position. Span tables span tables can be used to determine the size of a timber member of a particular strength class required for a given span. For spans in excess of 4 5 m two rows of strutting will be required positioned at the one third and two third span positions.

Where the joists span over 2 5m strutting is required to prevent joists twisting when loaded. For pitched roofs flat roofs and ceiling joists. Joist spans over 4 5m provide 2 rows of strutting at third span positions. Where the tables do not apply or where there are concentrated loads floor joists should be designed by an engineer in accordance with technical requirement r5.

Timber floor joists shall be adequate for the spans and loads and be correctly installed. Solid timber joist sizes are provided in the bs 8103 3 span tables. These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Proprietary strutting is to be used in accordance with manufacturers recommendations.