Shed Roof Purlin Size

Wet service factor c m 1 because purlins are protected from moisture by roof c t.

Shed roof purlin size.

Hi i am putting a pitched roof over my mobile home. Metal roof purlins are installed horizontally under metal roofs. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Because i am using.

Temperature factor c t 1 nds 2 3 3. The common 4 on center design is suitable for snow loads up to 60 for most applications. Allowable bending pressure f b f b c d c m c t c l c f c fu c i c r c d. For sake of discussion we will assume a minimal roof snow load of 20 psf pounds per square foot and a 4 12 roof slope.

Because this style of a shed has a flat roof it can facilitate a wider overhang which is ideal for storage. Wide span sheds then offered an experienced builder to oversee the erection of the new components at our own costs. Bending stresses f b. My rafters are 2x6 ridge beam is 2x8 collar ties 2x6.

The term plate means a major horizontal supporting timber. Load duration factor c d 1 15 nds 2 3 2 c m. The size of the roof overhang you choose depends largely on the style of your shed s roof. By supporting the rafters they allow longer spans than the rafters alone.

Higher snow loads and larger spans will require purlins to be spaced closer together than 24 on center in the drift area. Exterior paneling and all exterior sidings what size for purlins. For snow loads exceeding 60 trusses are recommended to be closer together. The rule of thumb is that the gusset should be twice the width of the wood you use for your rafters.

Engineers calculate this on a job site basis. You are going to cut out triangles that will cover the apex of each set of rafters. 20 psf x 949 1 5 psf x 12 x 949 x 11 625 2 8 x 3 0625 x 1 15 x 1 15 972 75 psi. With a flat shed roof the roof simply extends past the wall plate to provide an overhang.

A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. Purlin plates in wooden construction. Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16 size of rafters in mm 400mm 450mm 600mm. Despite the fact that it was found that wide span sheds were not at fault the directors paid for the new steel components to be supplied at our costs only to be reimbursed if there was a successful insurance claim.

Purlin plates are beams which support the mid span of rafters and are supported by posts. Check for gravity loads. For an 8 10 shed one sheet of plywood should be fine. Purlins are 2 by 4 feet and are installed much like metal roofing.