Do I Need A Vapor Barrier In My Attic

However all attics vented or unvented and in all climates should have an air barrier such as an airtight drywall ceiling.

Do i need a vapor barrier in my attic.

No you don t need a vapor retarder class i or otherwise. Not every wall does. You have loose fill insulation in the attic which doesn t have a vapor barrier. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.

Vapor barriers can also be important for certain rooms where moisture levels are especially high. 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. 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. Seal the air leakage pathways.

Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic. Vapour barrier is on the top of the rafter then insul then board if heating garage insul vapour then board need hatch for summer to let out hot air i m a insulator typar is a better product in a. It s also incorrect in a way. The theory is that part of the moisture vapor in the house is actually blocked by the drywall and paint on the.

In hot dry climates your attic can be vented though like in hot humid climates you should not install any vapor retarder or barrier. All attics vented or unvented should have an air barrier a properly detailed airtight drywall ceiling for example regardless of climate. Omitting a ceiling vapor barrier by arguing that you have to let the moisture escape or because the house has to breathe out the top is actually correct in a way. In circumstances where conditions inside a home or office are much different than outdoor conditions water vapor is likely to move through wall cavities and can get trapped inside and a well installed vapor barrier is recommended.

By the time you paint the drywall though you ve brought it into the class iii vapor retarder range between 1 and 10 perms and even less water vapor will diffuse through.