Putting Up A Moisture Barrier Metal Roof

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

Putting up a moisture barrier metal roof.

One common problem is moisture build up between two layers of roof type which must be avoided. In metal buildings there are a few possible consequences of trapped moisture in wall and roof systems. Corrosion of metal components even on surface treated metal. Metal roof over shingles condensation.

Single bubble vapor barrier and 2. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. It s also a good idea to discuss the options with your roofing contractor because they will be able to check the type of shingles your roof has and advise on the suitability of leaving the shingles in place or removing them. 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.

If you choose to omit the plywood from a residential construction install a vapor barrier between the purlins and the metal roof or plan to spray closed cell foam insulation between the rafters to eliminate the temperature differential between the air in the building and the metal. 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. But a preinstalled membrane may be even more effective at removing condensation. When exposed to moisture metal components can oxidize and weaken decreasing the life of your customer s building.

The problem with using. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. It blocks condensation from dripping into a pole barn and runs it out of the eaves as well as adding a slight r value to the roof and also. It doesn t matter if the air space is a half inch or six inches because the condensation factor will remain the same.

To know if you need a vapor retarder ask yourself a few basic questions. Metal roofs must be laid flat on a vapor barrier because steel will condensate if there s any air space underneath it. Put the steel down directly on a vapor barrier.