In most climates, it needs a vapor barrier. Some builders rely on batts with attached kraft-paper facing to do that job, but Tom recommends unfaced batts, covered in plastic with all the seams taped shut.

What do you cover unfaced insulation with?

Cover the newly installed insulation with a layer of plastic sheeting or other vapor barrier only if there isn't already a vapor barrier in place. If the insulation is installed over existing insulation, either faced or with a barrier over top, adding another vapor barrier will lead to structural problems.

Does paper faced insulation need a vapor barrier?

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.

Is a vapor barrier necessary?

A vapour barrier is an important component in building construction. Its purpose is to help prevent water vapour from reaching building walls, ceilings, attics, crawlspaces or roofs, where it can condense and cause building materials to rot or grow mould.

Does all 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.

Vapor Barriers: Need one or not?

Should you cover insulation with plastic?

Show activity on this post. 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.

Can you use unfaced insulation in exterior walls?

Unfaced insulation is non-combustible.

However, it's common for a layer of faced insulation to be used in the exterior walls and attic ceilings to prevent water from entering the home, while unfaced insulation can be added to improve the heat retention ability and reduce the risk of fire.

Should I put plastic over insulation before drywall?

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.

Where should vapor barrier be placed?

Vapor barriers are usually best installed on the side of the wall that experiences the hotter temperature and moister conditions: the inner surface in colder climates and the outer surface in hot, humid climates. In existing spaces, oil-based paints or vapor-barrier latex paints offer an effective moisture barrier.

Can you put vapor barrier on both sides of insulation?

In order to prevent condensation from forming, a vapor barrier should be placed on the warm side of your insulation to stop warm, moist air from condensing on a cold surface inside your wall. In cold climates like Canada, for most of the year the vapor barrier should be on the inside of the insulation.

When should you use unfaced insulation?

Unfaced insulation is great for new construction, remodels, walls, floors, ceilings, basements, attics and crawlspaces. It's best used for interior wall applications that do not face the outside and also in rooms that don't need moisture control, like living rooms, dining rooms and studies.

Do you need to put Poly over insulation?

Standard Installation Practices

Install the plastic sheeting only after the insulation, wiring and plumbing have been completed. Stretch the plastic sheet tightly across the top of the wall and staple it to the studs and plates with a hammer-tacker, a tool designed to install staples quickly and efficiently.

Do I need to cover unfaced insulation?

Fiberglass Insulation

In most climates, it needs a vapor barrier. Some builders rely on batts with attached kraft-paper facing to do that job, but Tom recommends unfaced batts, covered in plastic with all the seams taped shut.

Do you need to staple unfaced insulation?

Unfaced insulation goes up more quickly than insulation with paper or plastic facing. Flaps on faced insulation must be stapled between rafters to hold it in place. However, the lack of facing means that you must add a moisture barrier over the insulation.

Is it OK to use unfaced insulation in attic?

When installing between the roof rafters of finished attic spaces, you can use either faced or unfaced batting. When using insulation that has paper or plastic batting, that moisture barrier should face outward toward the attic space.

Can you staple vapor barrier?

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. Staple through the plastic into the sole plate -- the horizontal board running under the studs – at bottom.

Is Tyvek a vapor barrier?

Is DuPont^™ Tyvek^® a vapor barrier? No, DuPont^™ Tyvek^® is not a vapor barrier. It is made with unique material science to keep air and bulk water out while allowing moisture vapor inside walls to escape.

What is the best material to 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.

Do you need a vapor barrier when insulating a garage?

The majority seem to agree that insulated, unheated garages, should be allowed to breathe. If the garage is heated, you will need a vapor barrier, otherwise you will get frost and mold.

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.

Do vapor barriers cause mold?

One of the more common problems with crawl spaces that do not have a crawl space vapor barrier system is that they create high moisture levels, which may result in mold growth – as dampness creates the ideal environment for mold growth.

How do you secure unfaced insulation in walls?

Place unfaced insulation on top of existing material, such as loose-fill cellulose. Press the insulation firmly into place between joists, taking care to not compress the fiberglass and reduce its efficiency. Fasten batts loosely to perpendicular joists with plastic straps just to keep it from shifting.

What is the purpose of paper backing on insulation?

The Purpose of Insulation Facing

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. For this reason, faced insulation is typically installed on the "warm in winter" side of the wall.

Should insulation paper face in or out?

Regardless of whether fiberglass insulation is installed in a wall, attic, or crawlspace; the paper facing should always face toward the inside of the home. That's because the paper contains a layer of asphalt adhesive which prevents water vapor from passing through it.