Rob Ormiston
can metal go over wet shingles
4/22/2016
My metal roof blew of of a large portion of my barn. It has an old shingle roof and wood furing strips. Can I install the new metal roof over damp shingles and wood strips with getting mold? The ridgecap will have 1 inch foam under the edge to keep water out and the bottom of the roof panel will have foam also. Will it mold? Or any other concerns?. It rained yesterday but has been 80 degrees for the last week, and will rain again tomorrow. I am renting a lift and need to know if it will mold if roofed over ? I really appreciate your expertise. Thanks.
Todd Miller
Isaiah Industries, Inc.
4/22/2016
I would not anticipate any problems with this.
David Stermer
4/22/2016
Hi Roy, Thanks for your question about metal roofing. The IBC code does not permit roofing over a water-soaked roof covering (section 1510.3). I guess there is some interpretation required for a damp roof. The safe course of action is to wait for the roof to dry before installing metal. Trapped moisture certainly would support mold growth as well as corrosion of the metal roof from the inside. Regards, David
Eric Novotny
An informed customer is the Best Customer!
4/22/2016
I agree that it drying out is the best course of action. In this case, I am going to guess that as soon as it stopped raining though, that the shingles were basically dry. The shingles should not absorb that much water that they don't dry out in a matter of hours provided there is no rain. You do not want to cover it up like David said, if it is sopping wet.
Lynn Noesser
4/24/2016
I agree that the area should dry out very quickly. Additionally, if this is a barn with an open space to the lathing on the inside you would have plenty of air circulation from underneath to assist in the drying cycle.

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