Span Flat Roof Joist

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.

Span flat roof joist.

These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Live load is weight of furniture wind snow and more. 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 75 x 170 4 50 4 38 3 99. Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.

Dead load weight of structure and fixed loads 15 lbs ft 2. 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 full version allows any size. Span calculator for wood joists and rafters also available for the android os.

At least 40mm bearing on supports. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3. Span is clear span between supports.

1 psf lb f ft 2 47 88 n m 2. 2 are indicated below. 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. Usually 400 450 or 600mm but any value can be used up to 610mm max.

Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support. Maximum slop3 10 deg. Joist breadth 47mm. Surveyors span tables for designing roof rafters.

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 enter joist details 1 1 span and joist spacing. Flat roof joist calculator. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.

For pitched roofs flat roofs and ceiling joists. This is the distance between joist centres. Floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2. This demo version is fixed at 1m clear span.