Flat Roof Rafter And Joists

Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.

Flat roof rafter and joists. 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. Rafter fall rafter attached flat roof 5a page 23. 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.

Assuming that your builders have chosen to use wood for your house s frame your roofing joists ceiling joists rafters or trusses will be made from long planks of wood placed parallel to one another at evenly spaced intervals along the length of your roof. Rafters attached to ceiling beams. 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. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

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. The rafters in a flat roof serve as ceiling joists for the space below. 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. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.

Also available for the android os. Joists and rafters are components used in the construction of buildings. Continuous ceiling joists or collar ties span from rafter to rafter. Span calculator for wood joists and rafters also available for the android os.