Timber Roof Purlin 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.

Timber roof purlin sizes.

Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees. Purlins are the wood of 2 by 2 or 50mm by 50mm we nail the roofing sheets on. 2 by 2 i e 50mm by 50mm. Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16.

2 by 4 i e 50mm by 100mm. Purlins are spaced based on designs or type of roofing sheets. They both can be combined well to make sure that the space below the roof. Usually 400 450 or 600mm but any value can be used up to 610mm max.

For pitched roofs flat roofs and ceiling joists. All the figures are based on roofing tiles or slates laid on. This is the distance between rafter centres. Wood timber are sawn into various sizes amongst are.

2 by 3 i e 50mm by 75mm. Purlin and rafter roofs timber sizes and construction details author. But for our calculations we are using 900mm. Purlins near roof edges or changes of roof slope are subject to higher wind forces than interior purlins.

Roof pitch between 15 and 22 5 degrees with rafter spacing strength. Surveyors span tables for designing roof rafters. You don t have a nailing surface on the end of a 1x4. All about purlin span for metal 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. J l neal subject. Vc row vc column vc column text timber purlins supplier we have a large range of tanalised purlins in stock for timber contruction of farm and agricultural. As per as1684 and as4055 spanman adopts a nett pressure coefficient applied along the full length of the purlin of cpn 2 0 for non cyclonic zones n1 to n6 and cpn 2 5 for cyclonic zones c1 to c4.

If so you should use dimension lumber like 2x4. It is suitable to use for roof sheeting from fiber cement.