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 put vapor barrier before 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 a plastic vapor barrier with faced insulation?
In climates requiring a vapor retarder on the interior surface, a
kraft-faced insulation
is usually sufficient. When a loose-fill product such as fiberglass or cellulose is installed, a 4 mil continuous polyethylene sheet or a vapor retarder paint on the interior drywall should be used .
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.
Does vapor barrier go over insulation?
So one of your home’s most common vapor barriers — and one of the most important — is the one used
over the insulation in your exterior walls
. It’s designed to stop the moisture before it can enter the wall cavities. There are two basic types of vapor barriers used with exterior wall insulation.
Is Tyvek a vapor barrier?
No, DuPont
TM
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.
Can you put plastic over unfaced 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.
Can I use plastic as a vapor barrier?
You can use plastic if you put polyethylene between your drywall and the wall studs. … If you are framing out a below-grade basement, however,
do not use plastic as a vapor barrier
. Concrete tends to wick moisture, and if you cover insulated cavities with plastic they can become wet and optimal for mold growth.
Should I put plastic under my 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.
Can you put plastic over insulation in attic?
Once you talked about stapling down sheets of plastic over rolls of insulation. … In any case, a vapor barrier always faces the heated side, so
it would never be put on top of batt insulation in an attic
.
Can I put new vapor barrier over old?
Our best practices are that
the old vapor barrier is left in place and the new one is placed over it
. The old barrier even if it does not cover the entire crawl space serves to provide some additional moisture blocking and also help protect your new vapor barrier from any rocks or debris on your crawl space floor.
Which way does insulation face in a basement?
The first layer will sit between the joists, and the second layer will run perpendicular over the joists. The first layer should have the facing against the drywall to act as a vapor barrier. (The general rule for insulation is that
the facing always goes toward the conditioned space
.)
Where should vapor barrier be installed?
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.
How much does it cost to have a vapor barrier installed?
Overall, the average cost of installation for a vapor barrier is
between $1,200 and $4,000
. This includes materials and labor. Prices for materials vary more than those for labor (see the costs of different thicknesses, below, for an outline of different labor costs).
Can you put 2 layers of house wrap on?
3 Answers. There is no problem with doing this. Housewrap is “breathable” by design so you won’t trap moisture anywhere. You could build a wall with ten layers of housewrap and it would be more durable, not less.
Is it OK to staple Tyvek?
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.
