Putting Up A Moisture Barrier Metal Roof

In metal buildings there are a few possible consequences of trapped moisture in wall and roof systems.

Putting up a moisture barrier metal roof.

Corrosion of metal components even on surface treated metal. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating. Put the steel down directly on a vapor barrier.

Metal roof over shingles condensation. 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. Single bubble vapor barrier is a bubble wrap type material that is faced with reflective foil on the upper side and white vinyl on the inside. But a preinstalled membrane may be even more effective at removing condensation.

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. When exposed to moisture metal components can oxidize and weaken decreasing the life of your customer s building. 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. It doesn t matter if the air space is a half inch or six inches because the condensation factor will remain the same.

Several considerations must be addressed in the roofing system design including ensuring that the four barriers needed in any building enclosure i e water barrier thermal insulation barrier vapor retarder and air barrier are provided and are in the correct location for a given climate. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. To know if you need a vapor retarder ask yourself a few basic questions. Single bubble vapor barrier and 2.

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 using. 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.