Moisture Barrier Under Metal Roof

Architectural metal roofs with felt underlayment are best suited for buildings with proper slope and low moisture loads in dry or arid climates.

Moisture barrier under metal roof.

Felt underlayment provides little resistance to air and moisture vapor migration and does not serve as an effective air barrier. These covers are designed to block moisture damage and further insulate your home or business. What causes condensation on metal panels. When temperature and humidity conditions reach dew point moisture can condense on the underside of metal roofing and potentially cause water damage to the inside of your customer s building.

Most buildings especially those with metal roofing or siding can benefit from a roof vapor barrier. How does a vapor barrier work. In cold climates condensation in the roof may freeze into sheets which can also damage the roof. 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 will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer. The lower the pitch of a metal shed roof. Those drips from ceilings and surface moisture occur when warm air comes in contact with the cooler roofline or walls. Moisture can infiltrate the underside of metal roofs through condensation and strong rain events.

The key to getting condensation to evaporate is air flow. We recommend a polypropylene scrim reinforced underlayment made up of multiple layers. In a barn shop or other outbuilding you can attach your metal roof directly to the purlins. Condensation in a roof causes mold which is unhealthy and damages the integrity of the building.

In a residential application however condensation is a concern. Many metal roof problems are due to moisture. Once again this is used on cold roof construction. Having ventilation holes around the roof at eaves level and in the gable walls allows moisture rich air to escape.

Build your structure where possible in an elevated position with good natural drainage place a vapor retarder under floor gravel or concrete ventilate enclosed building when concrete is being poured and continue to ventilate until it is cured use heaters that are vented to the. This type of underlayment is critical to a quality roof installation. Moisture can collect on the inside of your metal roof whenever warm moist air inside your building meets the cold metal of your roof. It serves as a moisture barrier as well as a slip sheet.