Should I put plastic over insulation?

Without a vapor barrier in place, condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. Plastic, specifically 6-mil polyethylene plastic, is the most commonly used vapor barrier.

Should wall insulation be covered with plastic?

Without poly beneath the drywall, water vapor hits the drywall and diffuses through to the drier (in summer) indoor air. By installing a sheet of poly there, you cut off that drying mechanism and water that finds its way into walls can stay there longer and do more damage.

Can I put plastic sheeting over faced insulation?

More than likely, installing an additional layer of poly over kraft facing won't cause any problems — it's no more risky than if the wall had only unfaced batts and poly — and the risk of using poly on the interior is relatively low in a cold climate like New York's.

Should you put plastic over ceiling insulation?

Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days. You can forego the plastic and use a vapor retarder (kraft-faced insulation or latex ceiling paint) in all other climates except hot-humid or hot-dry climates.

Should I put Poly over faced insulation?

No, you should not do this. As mentioned above, faced insulation that has a vapor barrier can easily trap moisture. If you put another faced insulation on top of face insulation, a significant amount of moisture can form inside your insulation and in your walls to damage them.

Vapor Barriers: Need one or not?

Do you need vapor barrier over insulation?

After the insulation is in place you will want to add a vapor retarder, sometimes called a vapor barrier, if you need one. Not every wall does. A vapor retarder is a material used to prevent water vapor from diffusing into the wall, ceiling or floor during the cold winter.

Does ceiling insulation need a vapor barrier?

Vapor Blockers

Vapor barriers—sheets of plastic or kraft paper—keep water vapor out of the wall cavity, so the insulation stays dry. Not every type of insulation needs a vapor barrier. But if it does, the barrier should face inside in northern, heating climates, and outside in humid southern climates.

Can you put plastic over insulation in attic?

Plastic isn't recommended in this situation because it would create a second vapor barrier that can trap moisture and result in condensation and mold. Craft paper would have the same problem, this is what is most likely on the other side of the insulation for the vapor barrier you want.

Does fiberglass insulation have to be covered?

Whether your home has spray foam, foam board, or fiberglass roll (or batten) insulation, each type should always be covered because each poses hazards such as: Fire risk. Irritated skin issues (due to chemical irritants in the materials)

Are vapor barriers necessary?

Simple, no one. Here is the problem, moisture, condensation or vapor drive is inevitable. More simply, it is impossible to avoid some derivative of moisture in these cavities – with or without a vapor barrier.

How do you cover insulation with plastic?

Work down the wall, driving a staple through the plastic into the wall stud every 12 to 16 inches vertically. Tug and smooth the vapor barrier to ensure a completely smooth surface lacking wrinkles or gaps through which moisture and air may escape, defeating the vapor barrier's purpose.

Do I use faced or unfaced insulation?

Unfaced insulation—the type without paper—is what you would use if you are adding insulation to your attic or to place between floors when living space is above and below. Unfaced is also your best choice for adding soundproofing to interior walls.

Is Kraft-faced insulation considered a vapor barrier?

The facing on kraft-faced insulation is made of kraft paper with an asphalt coating that makes the paper impermeable to water vapor. The paper creates a vapor barrier that helps keep the water vapor in the warm, moist, heated indoor air from migrating outward into the wall or other structure.

What do you cover insulation with?

After the insulation is installed, it is necessary to cover it up with a vapor barrier so the glass fibers are not inhaled. The best vapor barrier to use is roll of plastic sheeting. This vapor barrier is easy to install and does an excellent job.

Do vapor barriers cause mold?

The Problem With Vapor Barriers

This can lead to significant moisture problems and mold; problems occur when walls get wet during construction or more often throughout the home's life.

Can you put vapor barrier on both sides of insulation?

Avoid installing vapor barriers on both sides of a structure. Walls and ceiling cavities should ideally have the ability to dry out in one direction if the other side is constructed to prevent moisture penetration. Seal all wall cracks and holes in the wall being vapor-proofed to block air gaps.

Is it safe to leave insulation exposed?

"Fiberglass insulation should never be left exposed in an occupied area, according to the American Lung Association," says ALA's Godfrey. "Exposed fiberglass insulation, once in the air, does cause respiratory reactions, such as dry, scratchy throat and coughing, as well as acting as a skin and eye irritant.

Can I cover fiberglass insulation with plastic?

Fiberglass insulation will not degrade unless exposed to water. The fiber could become airborne if a vent is blowing on it or it is disturbed in some way. It can be covered with a plastic vapor barrier to protect your home air quality.

How do you seal insulation?

Seal the gaps with caulk or expanding foam. When complete and dry, push the insulation back into place. Fill wiring and plumbing holes with expanding foam. Caulk around electrical junction boxes, and fill holes in box with caulk.

What kind of plastic do you use for a vapor barrier?

Reinforced polyethylene plastic sheeting (poly) comes in a variety of thicknesses and strengths. A 6 mil thick poly is commonly used as a vapor barrier and offers short-term savings to the homeowner.

Can you put foam board over fiberglass insulation?

If you can use the foam board and fiberglass - without compressing the fiberglass batts, then I say go for it. However, if you end up compressing the fiberglass then you will greatly lose the rated R-Value with an improper installation and almost certainly negate any possible benefits from the foam board.

Which way does the vapor barrier go on insulation?

Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. 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. In any case, the vapor barrier must point to the warm side.

Can you use 4 mil plastic for vapor barrier?

OVERVIEW. Our 4-mil plastic sheeting is a multipurpose film perfect for a wide variety of construction or DIY projects. This medium-duty plastic sheeting is commonly used as a vapor barrier in between insulation and drywall, used as a drop cloth or a temporary cover for equipment and supplies.

What is the difference between a vapor barrier and a moisture barrier?

Moisture barriers function to help in preventing water from entering inside of the wall cavity. On the other hand, vapor barriers basically prevent water vapor from the interior of the house to filter through the wall and condense on the warm side of the insulation.

What is the purpose of kraft-paper on insulation?

Kraft-Faced insulation is so named because it has a paper vapor retarder on the paper-facing side of the batt. This helps prevent mold and mildew, which is why this insulation type is most effective in exterior walls, basement walls, and attic ceilings for moisture control.