Putting Up A Moisture Barrier Metal Roof

The problem with this is that as the metal heats up and expands or cools down and contracts it moves a little on the roof.

Putting up a moisture barrier metal roof.

But a preinstalled membrane may be even more effective at removing condensation. The problem with using insulation alone. 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. I have a 16 x 20 unheated with no insulation garage that has shingles on it.

Traditionally condensation is managed by insulating the metal roof so that the panel temperature never reaches the dew point. 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. 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.

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. That reduction of air and moisture infiltration can then help improve roof longevity. 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. It serves as a moisture barrier as well as a slip sheet.

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. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. Once again this is used on cold roof construction. This type of underlayment is critical to a quality roof installation.