Old Roof Sdupport System Inspect Purlin

Fasten the purlin with 16d common nails into each vertical rafter.

Old roof sdupport system inspect purlin.

It s hard to fathom that the roof framing would have passed original inspection with this support system or lack therof. The support system for the roof is comprised of ridgepole and rafters or purlins. 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. 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.

Insert two equally spaced nails into the rafter. Conventional roof framing and roof trusses. Ply roof systems are also lightweight and utilized for retrofits over existing metal roofs figure 2. Photo above is from a jwk inspections framing pre drwall inspection in the san antonio south teaxas area showing the actual roof framing componenents.

I m not sure if it was original construction or not 1978 duplex though it looked like it. Snap a chalk line horizontally across the roof two feet down from the top. Using a combination of rafters and purlins is common. Dale nelson president of roof hugger left with red mcconnohie the product s inventor.

New panels being installed over roof huggers on an old roof above. Collar ties rafter ties tension beams structural ridge beams. Some of these can support the roof and prevent ridge sagging and wall spreading. 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.

Lay the first purlin at the ridge of the roof down to the chalk line beginning at either corner. Use purlins to create a supporting framework and to transfer the loads imposed by the sheeting onto the primary building structure. With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel. 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.

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. Roof huggers in place on an old roof.