Blown Attic Insulation Vapor Barrier

Some regions don t require a vapor barrier.

Blown attic insulation 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. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. Cima does not recommend the use of vapor barriers with cellulose insulation except in circumstances of exceptionally high moisture levels such as an indoor pool facility or very cold climates. 70 to 75 per sq.

With the added insulation the attic stayed cold and so did the ventilating air from outside which was now unable to effectively remove attic moisture. 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. Not every wall does. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below.

Now with attic insulation heat is no longer lost from the living space such that moisture may remain trapped in the attic vapor barriers were therefore necessary to reduce moisture flow into the attic. The heat being lost from the house below warmed up the attic so that moisture was lost through the vents as vapor. A common misconception is that all insulations require vapor barriers in all situations. 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.

Attic insulation new construction or retrofit work. But in some cases water vapor builds up in tight houses until it forces its way through the inside wall surface the vapor barrier and insulation hitting the back of the cool sheathing then. Hence the need to reduce moisture flow into the attic and the need for a vapor barrier. 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.

R value declines by as much as 50 percent at temps below 0 degrees f. Fluffy bits of spun glass that are noncombustible and can t decay.