Putting Up A Moisture Barrier Metal Roof

It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer.

Putting up a moisture barrier metal roof.

The problem with using insulation alone. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. Do i really need a moisture barrier underlayment for this project. That reduction of air and moisture infiltration can then help improve roof longevity.

In order to add moisture barrier under metal roof you can spray the undersides of the roof by using a thick layer of polyurethane spray foam. It serves as a moisture barrier as well as a slip sheet. This is often accomplished using vinyl backed fiberglass insulation to prevent humid air from coming into contact with the cooler metal roof which may be at or below the dew point. Some people think that they can just install the metal roofing right over the old shingles roof without any barrier in between but this is highly not recommended.

When you install a metal roof over a finished living space in just about any place other than the atacama desert where it s not rained for decades water vapor can and will float up through. Traditionally condensation is managed by insulating the metal roof so that the panel temperature never reaches the dew point. This type of underlayment is critical to a quality roof installation. A roof design that includes an adhered roof membrane with multiple layers of insulation with board joints offset and staggered over a vapor retarder air barrier helps lower the risk that air and the moisture it carries will infiltrate the roof system.

I have a 16 x 20 unheated with no insulation garage that has shingles on it. Once again this is used on cold roof construction. I plan on putting down 1 x 4 strapping on top of the shingles screwed to the joists and then screw the metal panels to the strapping. But a preinstalled membrane may be even more effective at removing condensation.