Roof Rafter Sizes For Pitched Roof

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.

Roof rafter sizes for pitched roof.

This is the distance between rafter centres. The length of rafter per meter of run is 1 1543. All we do now is use a calculator to multiply 1 610 by the measurement in the book. For pitched roofs flat roofs and ceiling joists.

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 are there any brittle finishes e g. Here the number is 941 86 inches. 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. 1 1543 x 1 610 1 858m.

It is always better to have a large rafter rather than be concerned with a sagging roof. Plasterboard on the underside of the rafter. Again make sure to consult local codes. Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak.

This means that for every 1m the rafter travels horizontally the angled length of the roof will be 1 1543m. 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. Here the number is 1166 66 inches.