Vapour Barrier Garage Ceiling

Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days.

Vapour barrier garage ceiling.

And the ceiling acts as a enough of a vapor retarder. First of all a garage is not a signicant source of vapor as it is not occupied that much and you don t cook or bath in in it. If you re using old uninsulated doors pick up a retrofit kit that add insulating panels. 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.

If you plan to insulate you should use a 6 mil poly vapour barrier on the walls and ceiling. Because the closed cell spray foam acts as a vapour barrier if you cover it again with the poly vapour barrier you will have condensation troubles between the two materials. However if you live in a cold climate zone such as alaska it s a good idea to install a vapor barrier on the warm in winter side of the wall. Most garages don t need vapor barriers because the amount of vapor that diffuses through garage walls ceilings and the floor is not enough to cause wet walls that result in moisture damages.

A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. If your garage is 45 degrees and you have a bonus room heated to 72 degrees above the garage the vapor retarder faces the upstairs room. As long a the ceiling is air tight and the ventilation is only above the garage adding ventilation is fine. Paper faced insulation is not a good vapour barrier.

If you re adding new garage doors be sure to install insulated options. A rigid vent with somewhat less free air area than the existing soffit ventilation is preferred since that lowers the pressure difference across your ceiling air barrier. Turbine vents are overkill. The classic answer is that the vapor barrier goes on the warm in winter side of the assembly.

You can forego the plastic and use a vapor retarder kraft faced insulation or latex ceiling paint in all other climates except hot humid or hot dry climates. Install as directed typically cutting to fit and using a staple gun to attach the vapor barrier to the studs.