Rafter And Purlin Roof Construction

Metal building roof purlins provide three structural functions.

Rafter and purlin roof construction.

Roofing terms when framing a roof figure 7 2 carpenters must be familiar with commonly used roofing terms figures 7 3 and 7 4. In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face. These structural supports run perpendicular across the rafter beams. In lightweight timber roof construction under purlins were used to support rafters over longer spans than the rafters alone could span.

Under purlins were typically propped off internal walls. Roofs and not for traditional purlin and rafter roof construction. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin.

There are two basic methods of pitched roof construction. J l neal subject. For example an 8 x 4 under purlin would support the center of a row of 6 x 2 rafters that in turn would support 3 x 2 roof purlins to which the roof cladding was fixed. They are inclined members spaced from 16 to 48 inches apart.

A notch in the rafter can be used on sloping purlins but a birds mouth is easier to locate and a quicker joint to cut on site. By supporting the rafters they allow longer spans than the rafters alone. The purpose of purlins. A cut roof this is the traditional method of cutting the timber on site and building up the roof using rafters ridge boards joists and purlins etc the exact details being determined by the size of roof size of timbers etc.

Rafters rafters make up the main framework of all roofs. Purlin plates in wooden construction. Building control guidance note purlin and rafter roofs timber sizes and construction details author. The tops of inclined rafters are fastened to.

Purlin plates are beams which support the mid span of rafters and are supported by posts. The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. Pitched roof construction.

2 the purlins allow the rafter to be birds mouthed over them thus avoiding the tendency for the rafter to slide off the roof. They vary in size depending on length and spacing.