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Roofing/IBR metal sheets on carport -condensation



I have carports that is giving us problems with condensation.

The carports have IBR metal sheeting and underneath is ISO boards its compressed polystyrene ceilings, during the night a lot of condensation happens and in the mornings it drips through the boards.

My question is what can I do to rectify the problem without taking down the ceilings again as it will break when removed,is there any solution to try and put something on top of the roof to try and keep the sheets from cooling down so drastically during the night.

I looked into torch-on membranes but it is a costly solution.Someone also recommended that i paint on a thick layer of industrial waterproofing roof paint.

Please if any can you give me a solution to my problem.

Thank you
Mari Lize

ANSWER: Somehow you need some insulation. Probably the easiest way to accomplish this would be to have the underside of the carport roofs sprayed with closed cell urethane foam.

Thanks for your question.

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Thank you but the problem is the ceilings cant be removed as it is attached to the IBR sheets  and if we do remove it it will break and all ISO boards will have to be replaced.

mari Lize

I believe that spraying to the underside of the ceilings will stop the problem though I realize that aesthetically that may not be pleasing.

I do not believe that applying any sort of coating or membrane to the top of the metal roof will change the situation.  

You could install a new roof system of some type which includes 2-4 inches of insulation or even vented airspace above the existing roof.  I think that would solve the issue as well.


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Todd E. Miller


I am available to answer any questions pertaining to residential (or other sloped) metal roofing. I have knowledge of most available products but I like to approach projects from a "needs" basis and analyze them individually. Additionally, I can answer most questions about building ventilation.


I have worked for a manufacturer of residential metal roofing since 1980. I currently serve as President and have been involved with a wide variety of projects of all types across the world.

I am a board member for Metal Construction Association, Metal Roofing Alliance, the local United Way, our church, and our son's school.

Over the years, I have had articles appear in several trade journals including RSI, Remodeling, and Qualified Remodeler.

I have a B.A. in Communications and have also completed three years of training with the E-Myth Academy.

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