Attic Insulation Moisture Barrier

Newly purchased house 75 years old.

Attic insulation moisture barrier.

If you do there is a chance that moisture that has slipped by the first vapor barrier will become trapped by the second vapor barrier decreasing the value of your insulation. If you live in a cold climate place the vapor barrier between the interior of your home and the insulation. Vapor barriers keep the air moisture in your house from condensing in the insulated cavities. This barrier is meant to keep moisture from getting to the insulation in the walls and ceilings and it is required by building codes when insulating most houses.

This worked well until we added large quantities of attic insulation. Lucyna de barbaro posted in energy efficiency and durability on october 4 2015 02 12am hello i am helping family with their attic insulation in east lansing mi. When adding additional insulation to an attic that is already insulated never use insulation with a vapor barrier. Some regions don t require a vapor barrier.

The attic has 2 ridge vents and 2 additional netted vents in the roof more centrally located. 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. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers. 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.

Whether your vapor barrier is a facing or a film it must be placed on the warm in winter side of the wall. 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. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

Most forms of attic insulation benefit from the addition of a vapor barrier to protect them from the harmful effects of moisture which can reduce their effectiveness over time the following are a few simple steps to help you undertake the task properly so your vapor barrier retains heat without damaging the insulation. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. Over time this trapped moisture can rot the wood framing in your attic or cause mold and mildew to appear. Not every wall does.

Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.