I just had a standing seam metal roof installed on my house.  My
builder is concerned that it may not be ventilated properly.  He
believes there should be an air gap between my tongue in groove
vaulted ceiling and the metal.  He claims that an air gap is needed to
provide proper ventilation for any moisture to escape, due to
condensation on the underside of the metal.  Is this necessary?

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Request for Question Clarification by redhoss-ga on 04 Mar 2005 06:52 PST

There is a pretty good answer to your question in this previous question:

http://answers.google.com/answers/threadview?id=456334

I hope that you at least have 30# felt installed under your metal
roof. I looked at several standing seam manufacturers websites and
could find none that recommended an "air gap". The general consensus
seems to favor a breathable membrane for best protection from
condensation.

I am not a researcher, but have many years in the building trades. 
There are a variety of questions here:  Is there a 'felt paper type
membrane' put down between the metal roof and the plywood or OSB
sheathing?  Did the builder install ridge venting?  Have you
considered checking in with the manufacturer's website tech help?  Has
his builder done this type or roof before?  Did he let you know of his
concerns prior to starting the project or once it was under way?
Were you acting as the general contractor or was the builder totally in charge?
Best of luck to you.

I work in the Home Improvement industry. I deal with ASC, Genesys
(Formerly Vic West) and Metal Sales Steel Roofing on a daily basis. I
cannot think of any reason why you should have an air gap between the
sheathing (your t&g roof deck) and steel roofing. If you had your
contractor put steel roofing over your existing 3-tab roofing, you
would of course have some sort of skip sheathing (1x4's) anchored to
the 3-tab. Now, when talking to my customers about insulation, an
entirely differnet subject, you need a 1-2 inch air gap between your
insulation and your T&G. This you cannot do with your application
since you actually see the underside of your roof decking. I do not
believe that you will have any problem with condensation with your
home.