Do I Need Vapor Barrier In Garage Ceiling

The space that will become the attic is vented via wall vents under the peak of the roof on both sides of the garage.

Do i need vapor barrier in garage ceiling.

Where the poly meets the spray foam at a. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. 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. This is normally done because it s the most cost effective method to achieve the desired level of comfort and ease of installation.

There should be a continuous ridge and soffit ventilation. Installing the vapour barrier in this type of insulated garage is a little different then normal. Without making sure of these components you could end up with a mold and mildew mess. Between the two air leakage moves far more moisture than vapor diffusion.

And the ceiling acts as a enough of a vapor retarder. Understand that this is a climate specific recommendation. And again do i need a vapor barrier. This will help to exhaust the water vapor that will collect.

Because you do not want to add a vapour barrier over the spray foamed area all you need to do is install one in the area that you did yourself. If you are going the extra mile to insulate your garage ceiling try to stay away from faced insulation. There s one other important qualification. Having said that i do not have a problem with relieving some of the moisture load in the house via diffusion hence a vapor retarder in a ceiling rather than a vapor barrier through a roof assembly that can handle it i e.

So poly the walls and ceiling and seal everything up well. Not every wall does. Vapor moves in two ways by diffusion through materials and by air leakage through gaps and holes in building assemblies. Unless you have converted your garage into a kitchen a bathroom a laundry room or a space that generates a lot of moisture even for that a dehumidifier can absorb all the moisture in the garage to keep the air dry.

Hence the need to reduce moisture flow into the attic and the need for a vapor barrier. The traditional way to insulate the walls and ceiling of a typical garage is to install fibreglass batt insulation in the walls and attic space followed by a six mil poly air vapour barrier and drywall. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. Whether or not you need a vapor retarder hinges on three main factors.