I have a 6 year old steel roof a older home that I purchased last fall.......
This spring I noticed that many of the screws are loose and not tight to the roofing.
The asphalt shingles were removed prior to the steel roof being applied.
The sheathing is not sheathing - it's 2 X 6 cedar laid diagonally on the rafters. The screws are 1 1/2" long.
I live in a northern climate, not unlike Spokane, Washington (less snow).
Does anyone know what is causing the screws to loosen or lift?
My guess would be that the screws holes have become somewhat enlarged over time. This is pretty much inevitable, especially in the substrate you mentioned. Basically the cedar is exposed to all sorts of temperature and humidity conditions since it's in direct contact with you attic air. It's likely that it absorbs a lot of moisture during some months, compressing the wood fibers. Then, during the dryer seasons when it dries out, the wood fibers don't spring all the way back to where they were. As this happens over and over, the screw holes get larger. By the way, this is the same thing that causes checking in wood, especially in boards that are constantly exposed to wet then dry, like deck boards. Anyway, once the holes enlarge, I would think the upward force of the wind might tend to work the screws out.
Josh
Porte Homme (takout) wrote:
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