Lumber Roof Loads

Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.

Lumber roof loads.

Wood screws withdrawal forces allowable withdrawal load force wood species moisture content and weight weight of green and air dried fire wood wood panel and structural timber products mechanical properties density fibre stress compressive strength and modulus of elasticity of clear wood panel and structural timber products. For roof live loads of 12 psf or 16 psf. For roof live loads less than 20 pounds per square foot psf rafter spans and required e values tabulated for 20 psf shall be permitted to be adjusted in accordance with the fol lowing table. The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot.

These numbers are for roofs supporting light loads of 20 pounds for square foot. Span calculator for wood joists and rafters also available for the android os. If you place the 2x6s at 16 o c then syp can span over 16 and spf can span 14. The roof load is composed of a dead load and a live load.

A clay tiled roof may have a dead. A complete analysis of wood s mechanical properties is complex but understanding a few basics of lumber strength will allow you to size joists and rafters with the use of span tables. For example if building is 24 x 24 and has trusses and the load on the roof will be for 30 lb snow load and a ceiling with no storage will total out like this. An spf roof at the same spacing and lumber size will span 11.

Sawn lumber limits design potential and in some cases just doesn t work. For heavy loads at 24 o c 2 6 syp can span up to 9. Let s start by taking a broad view. The dead load is constant and is estimated as 10 pounds per square foot for wood framed construction.

You can t beat sawn lumber for most small window headers but as spans and loads increase stronger materials are a better choice. Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope. The structural goal of a house is to safely transfer building loads weights through the foundation to the supporting soil. The load increases with the use of heavier roofing material.

Determine the load per square foot that the roof must support. The loads are based on adjusted roof snow loads from the governing building code. Spf 2 6 rafters can span 8. Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.