How do you vapor barrier a basement?

Polyurethane sheeting is a typical vapor barrier that contractors use to prevent moisture from penetrating the walls of a basement. The material is stapled to the frame of a basement wall before it is finished with plaster or drywall. A vapor barrier is also helpful to keeping a basement insulated and warm.

Where should I put the vapor barrier in my basement?

Vapor barriers should be located on the exterior of basement assemblies allowing inward drying to the basement space where moisture can be removed by ventilation or dehumidification.

Do you have to put a vapor barrier in basement walls?

Building codes usually require a vapor barrier (4 mil plastic sheeting) on exterior basement walls if the framing is attached to masonry or concrete surfaces, or if the wood framing butts up against the outer basement walls.

How do you install a vapor barrier in a basement floor?

How do you secure a vapor barrier to a concrete floor?

While laying the vapor barrier, ensure a 6-inch overlap along any seam between sheets. Seal the seams with no gaps using duct tape or moisture-resistant and long-lasting tape. Some plastic sheeting vapor barriers have self-sealing edges, so you don't have to worry about running out of tape or using the wrong kind.

How Vapor Barriers Work

Does vapor barrier go before or after 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.

Do you need vapor barrier in basement ceiling?

In the basement heat flow must be blocked, and “faced” insulation does a good job. With spray foam insulation (unfaced) there's no need for a vapour barrier because the installed material naturally acts as this barrier. A thermal barrier will need to be applied over the spray foam.

Should I put plastic behind drywall in a basement?

It's like sealing a wet blanket inside a plastic bag. Vapour barrier or not, any kind of fiber-based insulation is risky to use in basements. It could work out or it might not. Waterproofing the inside of the foundation wall does reduce the risk, but leaks or vapour infiltration are still a distinct possibility.

What happens if you don't have a vapor barrier?

The short answer is: if your wall doesn't have a vapor retarder, there is no need to worry. Builders worry way too much about vapor diffusion and vapor retarders. It's actually very rare for a building to have a problem caused by vapor diffusion.

How do you insulate basement walls to prevent mold?

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 install a vapor barrier on a cinder block wall?

Stick the vapor barrier material to the foundation seal tape and then use mechanical fasteners to hold it forever. Drill holes through the plastic and through the seal tape into the block. If you drill through the seal tape you will prevent the plastic from peeling off when you remove the drill.

Should you insulate concrete basement walls?

Walls. Basement walls should be insulated with non-water sensitive insulation that prevents interior air from contacting cold basement surfaces—the concrete structural elements and the rim joist framing.

Should you insulate basement walls below grade?

Your best bang for the dollar in this instance is to insulate the coldest part of the wall, again typically to 2-feet below grade. However, there are many instances where insulating the full wall is the best option, such as if your walls are stone, or the floor is earth or crushed stone with no vapor barrier.

Do you really need to insulate basement walls?

Insulating your basement may seem like a project best suited for another day, but truthfully, insulating your basement walls can help improve comfort and reduce energy and maintenance costs to HVAC systems. It also allows for extra living space within a home, which can be invaluable.

Can I install vapor barrier myself?

Provided you're not claustrophobic, installing a vapor barrier is a project most homeowners can DIY. You will need to calculate the square footage of your crawl space, so you can buy the appropriate amount of liner.

Which side of the wall do you put a vapor barrier?

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.

Should I 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.

Do I need vapor barrier over concrete?

You'll typically need a vapor barrier if you're installing flooring over concrete. Therefore, in high-humidity areas, moisture will move to a relatively low-humidity area, even through concrete.

Can I 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.