Flat Roof Joists Spacing

Before installing any roof joists always measure the area at least twice.

Flat roof joists spacing.

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. 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. The size of the ceiling joist also is accounted for in joist spacing. Spacing in exterior exposure.

Span calculator for wood joists and rafters also available for the. 1 ft 0 3048 m. Although 2 inch by 6 inch lumber is used most often in ceiling construction to support 5 foot by 8 foot sheetrock the material commonly used for ceilings other sizes of lumber may be used such as 2 inch by 4 inch and 2 inch by 8 inch lumber. Roof joists can be made of wood metal concrete or any number of materials.

In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Dead load weight of structure and fixed loads 15 lbs ft 2. Rafter and roof joist spacing is only one part of a complex roof design that works together to form a structure that meets building codes and can hold up the weight of the roof and roof load. Code of practice for permissible stress design materials and workmanship and bs 5268 7 2 1989 structural use of timber section 7 2.

Live load is weight of furniture wind snow and more. The figures are based on quality materials. Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41. 1 enter joist details 1 1 span and joist spacing.

Builders aren t bound by standard rafter spacing measurements. Live load psf dead load psf span calculator for wood joists and rafters available for the iphone. Usually 400 450 or 600mm but any value can be used up to 610mm max. The full version allows any size.

After all the roof joists have been installed take the time to measure the spacing again. Boarding to be fastened on top of flat roof joists with a depth to width ratio greater than 4 the allowable clear spans have been calculated in accordance with bs 5268 2 2002 structural use of timber part 2. Just because one material may be stronger than another doesn t mean the. 1 psf lb f ft 2 47 88 n m 2.

The tables below give maximum spans for rafters and beams. This demo version is fixed at 1m clear span. But they do tend to space rafters in one of several industry standard increments typically. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

Flat roof joist calculator.