Metal Roof Rafter Span Tables

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.

Metal roof rafter span tables.

Imposed loads roof snow load and short term point load. Surveyors span tables for designing roof rafters for pitched roofs flat roofs and ceiling joists 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. Are there any brittle finishes e g. The span tables have been prepared for attached 1 side and free standing 4 sides open or 3 sides open 1 enclosed sides pitched roofs that are empty under 50 blocking in accordance with as nzs 1170 2 2011 requirements.

The imposed uniformly distributed live load in the main span. These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. 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.

Span tables all span tables. Design of single span rafters in roofs in houses office buidlings schools and other structures. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. This diagram illustrates the typical arrangement of a rafter and purlin roof and shows the dimensions referred to in the tables above.

This is the distance between rafter centres. Rafter spans for southern yellow pine douglas fir and eastern spruce. Usually 400 450 or 600mm but any value can be used up to 610mm max. For other awning arrangements use the awning selection tables section to determine type and reduction factor.

Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002. Plasterboard on the underside of the rafter. Gable walls need to be strapped to the roof at the maximum 2m centres using 30 x 5m galvanised mild steel straps. Click here for structural design calculations.