Pitched Roof Timber Sizes

The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.

Pitched roof timber sizes.

Automatically calculate suitable rafter sizes enter a specific rafter size 1 3 timber strength. With purlin spacing of. 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 following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.

All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. It has been my experience to never use a beam smaller than a two ply 2 x 8. Roof pitch is the measurement of a roof s vertical rise divided by its horizontal run. There are two basic methods of pitched roof construction.

22 5 and 30 degrees. 0 75 kn m snow load. Pitched roof timber sizes 1. Pitched roof timber sizes.

All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. For pitched roofs flat roofs and ceiling joists. This calculator matches up with 90 of the applications in the 2012 international residential code book. Surveyors span tables for designing roof rafters.

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. 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. Structural calculations for timber joists timber beams glulam beams flitch beams using the latest design codes. Shingle roofs typically have a life span of 15 30 years while membrane roofs usually last 5 15 years.

Imposed loads roof snow load and short term point load altitude not exceeding 100m. It is often compared to slope but is not exactly the same. Most interior beams need to include the roof load. A cut roof this is the traditional method of cutting the timber on site and building up the roof using rafters ridge boards joists and purlins etc the exact details being determined by the size of roof size of timbers etc.

Although ceramic tile roofs are expensive they can have a life span of over 100 years. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction. If there is are any questions about anything else then you should contact your supplier or an engineer.