Old Roof Sdupport System Inspect Purlin

Use purlins to create a supporting framework and to transfer the loads imposed by the sheeting onto the primary building structure.

Old roof sdupport system inspect purlin.

Photo above is from a jwk inspections framing pre drwall inspection in the san antonio south teaxas area showing the actual roof framing componenents. 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. 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. Using a combination of rafters and purlins is common.

Ply roof systems are also lightweight and utilized for retrofits over existing metal roofs figure 2. Snap a chalk line horizontally across the roof two feet down from the top. Insert two equally spaced nails into the rafter. New panels being installed over roof huggers on an old roof above.

The support system for the roof is comprised of ridgepole and rafters or purlins. Dale nelson president of roof hugger left with red mcconnohie the product s inventor. The lack of which imo allowed the purlin to twist away from the rafter. 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.

Collar ties rafter ties tension beams structural ridge beams. It s hard to fathom that the roof framing would have passed original inspection with this support system or lack therof. Fasten the purlin with 16d common nails into each vertical rafter. 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. Conventional roof framing and roof trusses. We won t go into attic inspection too deeply since this series of articles from mastering roof inspections is primarily about roofing defect recognition but you should have an understanding of the two main basic roof structure systems. I m not sure if it was original construction or not 1978 duplex though it looked like it.

With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel. Roof huggers in place on an old roof.