Vapour Barrier Garage Ceiling

As long a the ceiling is air tight and the ventilation is only above the garage adding ventilation is fine.

Vapour barrier garage ceiling.

If you re adding new garage doors be sure to install insulated options. 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. If you plan to insulate you should use a 6 mil poly vapour barrier on the walls and ceiling. 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.

Install as directed typically cutting to fit and using a staple gun to attach the vapor barrier to the studs. To know if you need a vapor retarder ask yourself a few basic questions. The classic answer is that the vapor barrier goes on the warm in winter side of the assembly. 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.

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. Plastic vapor barriers should only be installed in vented attics in climates with more than 8 000 heating degree days. 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. And the ceiling acts as a enough of a vapor retarder.

Turbine vents are overkill. 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. This is because no matter how warm you keep you garage when that overhead door opens you fill the garage with cold moist air and this will build up as condensation between the poly and the spray foam. You don t mention whether there is a bonus room or living space above the garage.

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.