Old Roof Sdupport System Inspect Purlin

Ply roof systems are also lightweight and utilized for retrofits over existing metal roofs figure 2.

Old roof sdupport system inspect purlin.

Using a combination of rafters and purlins is common. Purlins are not required or needed unless rafters are overspanned and then the purlins serve as support to prevent roof sag deflection due to the overspanned and or undersized rafters. Insert two equally spaced nails into the rafter. With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.

Fasten the purlin with 16d common nails into each vertical rafter. The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge. Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc. Use purlins to create a supporting framework and to transfer the loads imposed by the sheeting onto the primary building structure.

Snap a chalk line horizontally across the roof two feet down from the top. The use of purlins as opposed to closely spaced rafters is common in pre engineered metal building systems and both the ancient post and beam and newer pole building timber frame construction. Some of these can support the roof and prevent ridge sagging and wall spreading. This article describes and illustrates the different types of support that prevents roof sagging and wall bulging at buildings including definitions of collar ties rafter ties and structural ridge beams.

Dale nelson president of roof hugger left with red mcconnohie the product s inventor. The support system for the roof is comprised of ridgepole and rafters or purlins. Photo above is from a jwk inspections framing pre drwall inspection in the san antonio south teaxas area showing the actual roof framing componenents. Many single ply membrane roofs rely on the existing metal roof to function as a structural deck for support and attachment of the roof system including board insulation as well as for support of live snow and wind.

Conventional roof framing and roof trusses. The lack of which imo allowed the purlin to twist away from the rafter. Collar ties rafter ties tension beams structural ridge beams. I m not sure if it was original construction or not 1978 duplex though it looked like it.

New panels being installed over roof huggers on an old roof above. Roof huggers in place on an old roof.