Metal roof fasteners

[Kudzu]

Long time since I posted here. But I have a question. I ran into a metal roof today that was installed with the fasteners in the valley of the corrugated sheets. I am under the impression that the fasteners should be installed on the ridges and not the valleys. Am I mistaken?

[JEuriech]

I think it depends on if they are primary fasteners or secondary fasteners. I believe primary fasteners can be in the valleys.

Here are some web sites that you can check:

http://www.mtlsales.com/Technical/

http://www.metalroofing.org/

http://www.mcrma.co.uk/pdf/mcrma_t10.pdf

Jeff Euriech

Peoria Arizona

[Jim Katen]

Originally posted by Kudzu

Long time since I posted here. But I have a question. I ran into a metal roof today that was installed with the fasteners in the valley of the corrugated sheets. I am under the impression that the fasteners should be installed on the ridges and not the valleys. Am I mistaken?

Some manufacturers specify installing the screws on the flat part of the metal. Some specify installing them on the ribs. You'd have to find the installation instructions for the particular product that you were looking at.

In my experience, the skill of the installer is way, way, way more important than the location of the screws.

- Jim Katen, Oregon

[Chad Fabry]

Most of the metal buildings and roofs around here are now being installed by fastening in the flats. The screws should have a captive washer (in a cup) when used on roofs.

[kurt]

Almost always flats. If you run the fasteners in the ridges, they move back & forth when the panels expand & contract. Eventually, the washer opens up a gap & leaks. In the flats, they don't move back & forth nearly as much, and the washer can maintain it's seal better.

Like Katen said, depends on mfg., but it's almost always flats nowadays.