Flat Roof Rafter And Joists

There is no need for bearing posts under the ridge board which is nonstructural.

Flat roof rafter and joists.

Span calculator for wood joists and rafters also available for the android os. These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Also available for the android os. In a typical roof framed with dimension lumber the rafters rest on the exterior wall top plate at the lower end and bear against a ridge board at the top.

Understanding the difference between them is essential for those working in the construction trades while basic knowledge is useful for homeowners if repair and maintenance issues arise. Rafters attached to ceiling beams. They are nailed securely to exterior wall plates and to each other. 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.

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. Continuous ceiling joists or collar ties span from rafter to rafter. The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof. 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.

Joists and rafters are components used in the construction of buildings. The rafters in a flat roof serve as ceiling joists for the space below. Rafter fall rafter attached flat roof 5a page 23. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.