Roof Rafter Spacing Uk

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak.

Roof rafter spacing uk.

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. Usually 400 450 or 600mm but any value can be used up to 610mm max are there any brittle finishes e g. Here the number is 941 86 inches. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall. Plasterboard on the underside of the rafter. Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.

Mm this is the distance between rafter centres. Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16 size of rafters in mm. Surveyors span tables for designing roof rafters. But they do tend to space rafters in one of several industry standard increments typically either 12 16 or 24 inches apart.

These spans were calculated using our flat roof joist calculation. Builders aren t bound by standard rafter spacing measurements. For pitched roofs flat roofs and ceiling joists. It is always better to have a large rafter rather than be concerned with a sagging roof.