Existing metal roof condensation solutions?

Cliff Farman
I bought a house in SW FL with a metal shop building. It's a carport style building with horizontal siding/roofing, uninsulated. The 2 1/4" square tubing trusses, have a lower chord, that I would like to attach a ceiling to. (Under the truss lower chord) I would then put insulation on top of the ceiling. Do I need to put in a vapor barrier, and if so where? One thought was to put the vapor barrier on the bottom of the lower truss chords, and put the ceiling (metal) under the barrier. If I only wanted to insulate 1/2 of the building, with the dropped ceiling, Would the vapor barrier do anything, with the roof over the enclosed area, being open to the uninsulated part of the building? Spray foam in out of the budget. Thoughts on this?
Eric Novotny
An informed customer is the Best Customer!
Are you going to condition the space? Vapor retarder levels should go to the warm side in in FL, that is the exterior wall/roof/etc. If you are not going to condition, don't worry about it as you won't have cool enough interior temps to create a condensing surface in a majority of the situations. I would look at some foil faced rigid foam to help reject some of the radiant heat. Is the roof vented?

If you would like to reply to this thread, please log in. If you do not have an Ask the Experts forum user account, create one here.

Find a Professional

Get Started Today

Take the first step to increasing the value of your home with a great looking, durable, fire resistant and energy efficient metal roof. Browse our list of qualified MRA Member Roofing Professionals in your area for a free consultation and estimate.