Metal Roof Decking Question

Haven’t done a lot of metal roofs and so hoped someone could answer a couple questions for me.

Did an inspection today on a house built in 2006 that had a metal roof. While in the attic, I noticed that there was no plywood or OSB sheathing/decking between the rafters and the metal sheets. Is this allowable/correct? All the metal roofs I have seen have had some sort of decking, but then again, most of those roofs were installed over an already existing roof.

Also, there was a vent pipe that didn’t go through the roof. I assume that is incorrect for a metal roof as it is for a shingle roof.

Any help would be appreciated.

Roof-Attic View.jpg

Roof-Attic View.jpg


the purlins support the metal roof without sheating Clint, but You are right about the vent…that is just plain wrong…IMO…jim

Thanks, Jim.

Is that a typical metal roof installation for a new roof, i.e., with no decking/sheathing? If so, is it done that way because it is cheaper and/or faster? Just curious…

Yes to all of the above as far as I know…I’m sure no expert , but this is the way i see them on new construction…jim

This link may help a little.

Marcel :slight_smile: :smiley:

In your photo there appears to be a lot of eave daylight. That usually is an indication that the profile vent/stop material was not installed, is displaced or has failed.

Vermin, insects and birds can become problematic when this feature is omitted. This is not necessarily a defect, more of a nuisance issue and advising the client along with a note in the report…avoids call-backs :roll:


Thanks fellas. That was a big help!

I see a lot of metal roofs and have never seen one installed without roof sheathing. According to this link it depends on the product. Most metal roofing is not very thick. Did you walk the roof? I would definitely call out the lack of a membrane.

Could this house be a converted shed?
Up here in wet country, on a closed-in dwelling with heat, some kind of sheathing would be recommended, and even 15 lb felt is better than nothing.
But just tin on strapping is pretty common for sheds and workshops with lots on open air under them. Makes it easier to find the leaks after a windstorm! :smiley:

John Kogel