Should you put plastic behind 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.

Do you need a vapor barrier between insulation and drywall?

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.

Do you use vapor barrier on inside walls?

However, if a vapor barrier is required for the building, the general rule is to put it on the interior. This is the recommended placement because any humidity is more likely to come from the inside of the home than from the outside.

Can you use plastic sheeting as 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.

Is it OK to cover insulation with plastic?

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.

Vapor Barriers: Need one or not?

Is 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.

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.

Can I use plastic instead of Tyvek?

You can use plastic if you put polyethylene between your drywall and the wall studs. This way, you should get a tighter wall without trapping moisture inside the exterior walls. If you are framing out a below-grade basement, however, do not use plastic as a vapor barrier.

Is Tyvek considered 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.

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.

What is the difference between vapor barrier and 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.

Does paint act as a vapor barrier?

Two coats of a good oil paint will provide a vapour barrier of less than 1 Perm as well. There are even some latex vapour barrier primers that will do the job.

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.

Can you use 4 mil plastic for vapor barrier?

4 Mil Clear Plastic Sheeting - . 004 inches thick plastic sheeting engineered from low-density polyethylene. Our rolls of clear plastic sheeting are strong and durable - they will not tear or rip easily. Useful as a painter's tarp, vapor barrier, or for general use.

Do I need a vapor barrier if I have house wrap?

House wrap material does not need to be an air barrier, BUT the product used must be installed to manufacture specs (which most likely includes sealed joints and seams).

Is tar paper considered a vapor barrier?

Fortunately a number of materials, including traditional asphalt felt (tar paper) have this ability to stop liquid water while remaining “permeable” to water vapor.

Can you staple Tyvek house wrap?

Tyvek says you can use 4 staples per 9 feet of house wrap if you tape over them an apply the siding right away. But a cap stapler is better. Apply house wrap up the gables before installing exterior trim, even if the attic is not conditioned.

Should you put plastic on basement walls?

Should I use Visqueen or plastic sheeting on the framed basement walls? No, you should not, as plastic will prevent moisture from moving through the wall and will lead to mold and damage.

Why are houses wrapped in plastic?

Housewrap (or house wrap) generally denotes a synthetic material used to protect buildings. Housewrap functions as a weather-resistant barrier, preventing rain from getting into the wall assembly while allowing water vapor to pass to the exterior.

Why are vapor barriers bad?

Vapor barriers are supposed to stop vapor diffusion through roofs, walls, and floors. But they can also can trap moisture, causing rot and mold. Where moisture comes from: Water vapor can be forced into wall assemblies from the warm side of the house.

How important is a moisture barrier under house?

A vapor barrier is important for a couple of reasons. Firstly, the air in your crawl space enters your home. Your home is made of porous materials, such as wood, concrete and fiberglass insulation. Also, in part, the air in your HVAC unit circulates air from your crawl space into your home.