![]() ![]() They provide detailed specifications on the strength and span of different types of steel rafters. Steel roof rafter span tables are designed to help you choose the appropriate rafter for your roof. Steel roof rafter span tables provide the information needed to make an informed decision when selecting a rafter type. Different materials have different strengths and span limitations, so it is important to take these factors into account. The most important factor is the overall span of the rafters, which is determined by the size of the roof and the type of steel used. When it comes to steel roof rafters, there are a few things to consider before choosing the right product for your home. But with so many different types of steel rafters, how do you know which one is best for your home? That's where steel roof rafter span tables come in. Steel rafters are strong, durable, and can last for decades if installed correctly. They provide the exact measurements needed to ensure the integrity of your roof and provide the necessary support for a safe and secure structure. The imposed load should be calculated in accordance with BS 6399:Part 3:1988 Code of practice for imposed roof loads, as a rule of thumb for altitudes not exceeding 100m you can use a uniformly distributed load of 0.75 kN/m² and for most other areas exceeding 100m but not exceeding 200m you can use 1 kN/m², for parts of Scotland, Pennines, North East England and heights over 200m you will need to refer to BS 6399 Part 3.Steel roof rafter span tables are an invaluable tool for anyone considering building or remodeling their home. Rafters are to have minimum end bearing of 35mm. Wane as allowed in BS 4978:2007+A2:2017 is permitted in all sections included in these span tables. Timber to be covered, these span tables do not apply to timber which is fully exposed to the elements. Holes and notches cannot be drilled or cut into the rafters unless proved adequate by specialist calculations. ![]() The calculations on which these span tables are based conservatively assume that the rafters are not continuous over the purlins, but they can be continuous over the supporting purlin if required. These span tables are based on the assumption that the tiling battens fastened to the top of the rafters will provide adequate lateral restraint and also ensure that lateral loads are distributed. It is also assumed ceiling joists will be used to transmit the horizontal component of thrust occurring at eaves level to complementary rafters. These span tables only apply to roof systems with four or more rafters. These span tables do not apply to trussed rafter roofs. The dead loads shown at the top of span table above do not include the self weight of the rafters, however, the rafter self weights are included (in addition to the dead loads) in the calculations used to determine permissble clear spans. The allowable clear spans have been calculated in accordance with BS 5268-2:2002 Structural use of timber - Part 2: Code of practice for permissible stress design, materials and workmanship and BS 5268-7.5:1990 Structural use of timber - Section 7.5 Domestic rafters. Dead load per square metre (in kN/m²) supported by raftersĬentre-to-centre spacing of rafters (in mm) ![]()
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