Do I Need A Vapor Barrier For Attic Insulation

The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it.

Do i need a vapor barrier for attic insulation.

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. To be able to answer this question correctly for your home there are a few factors you need to consider before any major attic insulation project. Hence the need to reduce moisture flow into the attic and the need for a vapor barrier. If you need a vapor barrier and your insulation is unfaced you must cover it with a polyethylene film.

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 facing on faced insulation acts as a vapor retarder. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. I install my vapor barrier in the middle of the wall system between the two walls.

Take the measurements with you when purchasing materials. Do not overlook attic access door. 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. Measure the entire area and write down the results.

This worked well until we added large quantities of attic insulation. If you are planning to have an attic insulation project for your home you may be wondering whether it is important to have a vapor barrier installed as well. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. In mixed climate areas the vapor barrier is optional depending on the total design of a building.

In cold climates a vapor barrier is almost always needed. Take a note of the construction of the attic and figure out which type of barrier will be suitable. Not every wall does. To install an efficient vapor barrier you need the dimensions of the room.

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.