Metal Roof Experts

[homnspector]

I don't run into many metal roofs. Is there supposed to be flashing between the roof jacks and metal roofing, that is, secondary flashing above the metal roof? These have a roof jack attached to the roof sheeting and a hole cut in the metal for the vent. The roofing is sealed to the roof jack with silicone. It looks wrong to me as it is not possible to cut that accurately so quite a bit of sealant is needed to fill the gap.

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[SonOfSwamp]

It's highly likely that the manufacturer of that roof system has specs that show the right way to flash those vents.

I can tell you with high confidence that running a bead of caulk around the holes is not the right way to waterproof those vents.

I always got the manufacturer's specs. Best I recall, I never found an installation that conformed to the specs.

For general info/specs on flashings and metalwork in general, one needs a SMACNA manual.

WJ

[Jim Baird]

The metal roofing vendors sell a jack that goes outside with a very malleable wide flange that has to be sort of mashed (note that word is used South of a certain geographic line instead of "press", as in "mash the button" instead of "press the button".) to conform to the roof profile, then silicone caulked. It still relies on caulk. I've had roofers tell me they are no better than just gobs of goo.

[Jim Katen]

Originally posted by Jim Baird

The metal roofing vendors sell a jack that goes outside with a very malleable wide flange that has to be sort of mashed (note that word is used South of a certain geographic line instead of "press", as in "mash the button" instead of "press the button".) to conform to the roof profile, then silicone caulked. It still relies on caulk. I've had roofers tell me they are no better than just gobs of goo.

Those boots are supposed to be installed with the caulk between the metal roof surface and the boot to make a caulk sandwich. Once it's stitched in place with screws, this creates a very effective gasketed joint.

If you just caulk two adjacent surfaces on a metal roof, the metal will move and the joint will fail. If, on the other hand, you create a gasket, it'll last for a long, long time.

- Jim Katen, Oregon

[Bain]

Those exposed fasteners are yucko. The grommets dry-rot after several years and begin to leak. Make certain you advise your client about this to protect your keister.

These kinds of roofs are becoming more popular in my area 'cause they're inexpensive to install. I've seen several where the undersides of the decking were streaked from water seeping in around the nail holes.