Flat Roof Joists Spacing

Builders aren t bound by standard rafter spacing measurements.

Flat roof joists spacing. 1 enter joist details 1 1 span and joist spacing. This is the distance between joist centres. Live load psf dead load psf span calculator for wood joists and rafters available for the iphone. The size of the ceiling joist also is accounted for in joist spacing.

But they do tend to space rafters in one of several industry standard increments typically. Just because one material may be stronger than another doesn t mean the. Dead load weight of structure and fixed loads 15 lbs ft 2. Flat roof joist calculator.

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. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Code of practice for permissible stress design materials and workmanship and bs 5268 7 2 1989 structural use of timber section 7 2. The figures are based on quality materials.

The tables below give maximum spans for rafters and beams. 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. 2 are indicated below. 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.

The full version allows any size. 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. 1 psf lb f ft 2 47 88 n m 2. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Spacing in exterior exposure. Roof joists can be made of wood metal concrete or any number of materials. After all the roof joists have been installed take the time to measure the spacing again. 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.

Span calculator for wood joists and rafters also available for the. Usually 400 450 or 600mm but any value can be used up to 610mm max. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Live load is weight of furniture wind snow and more.

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.