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.

Moisture can infiltrate the underside of metal roofs through condensation and strong rain events. Moisture can collect on the inside of your metal roof whenever warm moist air inside your building meets the cold metal of your roof. What causes condensation on metal panels. Most buildings especially those with metal roofing or siding can benefit from a roof vapor barrier.

Make sure the product is designed to be used under metal. Condensation in a roof causes mold which is unhealthy and damages the integrity of the building. 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. 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.

In a residential application however condensation is a concern. How does a vapor barrier work. Once again this is used on cold roof construction. Having vents in all elevations of the shed is an effective way of minimising metal roof sweating.

In cold climates condensation in the roof may freeze into sheets which can also damage the roof. Many metal roof problems are due to moisture. Moisture damage from rain snow and ice is a big no no when it comes retaining the integrity of any building. Felt underlayment provides little resistance to air and moisture vapor migration and does not serve as an effective air barrier.

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. Having ventilation holes around the roof at eaves level and in the gable walls allows moisture rich air to escape. It serves as a moisture barrier as well as a slip sheet. We recommend a polypropylene scrim reinforced underlayment made up of multiple layers.

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. Those drips from ceilings and surface moisture occur when warm air comes in contact with the cooler roofline or walls. In a barn shop or other outbuilding you can attach your metal roof directly to the purlins. The key to getting condensation to evaporate is air flow.