Thickness Of Vapor Barrier For Attic

Most authorities now agree that vapor barriers are important under certain conditions but not necessarily as a whole house solution for every home.

Thickness of vapor barrier for attic.

On the other hand an air barrier a properly detailed air tight drywall ceiling for example in the absence of a vapor barrier can be effective since it stops the flow of vapor laden air. Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. No you don t need a vapor barrier. A vapor barrier in an attic assembly in a severely cold climate with the absence of an air barrier will likely be ineffective.

Attic vapor barrier detail for cold climates the best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. Plastic specifically 6 mil polyethylene plastic is. The thickness of your vapor barrier is just one of the many considerations you need to take into account when installing a crawl space encapsulation system.

Avoidance of the installation of vapor barriers such as polyethylene vapor barriers foil faced batt insulation and reflective radiant barrier foil insulation on the interior of air conditioned assemblies a practice that has been linked with moldy buildings lstiburek 2002. Whether using loose fill or batts put the vapor barrier closest to the warm side of your installation where hot moist air would get in facing the house s interior in cold climates beneath floor insulation and the attic s interior in hot climates on top of floor insulation. The basics of air sealing are covered in this article. Do not add a vapor barrier on top of the insulation in your attic since the paper facing on the existing insulation is the vapor barrier.

Choosing a crawlspace vapor barrier thickness. Resolution of the vapor barrier debate. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. What you need is an air barrier that is at every step of the way you have to pay attention to airtightness.

There are two measurements you should be familiar with when choosing your poly for your crawlspace vapor barrier. Polyethylene sheeting is measured in mils a mil is equal to 0 001. Some regions don t require a vapor barrier. Air sealing an attic.

Mils is the measurement of the poly s thickness and perms represent permeability to moisture. In circumstances where conditions inside a home or office are much different than outdoor conditions water. When it comes to the stairway leading into your attic you should heed the advice in this article.