A continuous geomembrane or plastic liner behind the drywall protects the interior walls from any water damage. Because bathrooms and kitchens produce the most water vapor of any house or building, it has become standard practice to also use semigloss paint on the walls to act as a secondary vapor barrier as well.
Regardless of your environment, you should consider using a moisture barrier in basements and crawlspaces as well as beneath flooring and behind the drywall in high-moisture places like kitchens and bathrooms. It's better to be safe than sorry when moisture damage could put your home's structural integrity at risk.
Because a vapor barrier is a low permeable barrier, it keeps moisture from passing through. This is beneficial to keep moisture away from a dry surface but will trap moisture behind it if installed on a water-damaged concrete wall, causing the wall to fail further.
“For minor projects, the absence of a vapor barrier leads to water intrusion, leading to an unstable foundation or a cracked slab.” The American Society for Testing and Materials (ASTM) outlines national standards for underslab vapor barriers.
This liquid water can accumulate on interior walls and between internal and external walls. If it accumulates excessively, it can result in a significant damp issue. To safeguard your structure from the detrimental effects of dampness, it is advisable to install vapor barriers or a damp proof membrane.
Yes, covering your insulation with a vapor barrier plastic before installing drywall is crucial.
VCLs are a requirement in Building Regulations in certain new build situations. Existing properties might require a VCL if you are: introducing internal stud walls and insulation. installing a new concrete floor with insulation.
Materials such as rigid foam insulation, reinforced plastics, aluminum, and stainless steel are relatively resistant to water vapor diffusion. These types of vapor retarders are usually mechanically fastened and sealed at the joints.
Painted drywall should not be considered a Class III vapor retarder unless the paint is rated/tested at ≤10 perms – standard paint should be considered vapor permeable (not a vapor retarder). Wall components have vapor retarding characteristics that can affect moisture migration.
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.
Bathrooms and Kitchens: Due to high moisture levels, vapor barriers are particularly important in bathrooms and kitchens. They are often installed behind the drywall and around plumbing fixtures to prevent moisture from penetrating the walls and causing mold growth.
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.
If you live in a mixed climate – hot and humid with several heating months in the winter, you probably need a vapor retarder. Specifically, if you live in climate zones 4C (marine), 5, 6, 7 and 8. Not sure your climate zone? You can check here.
There are many types of insulation from which to choose when looking to put something behind your drywall. Here is a look at three of the most common types: Fiberglass batting and blankets, spray foam, and blown-in insulation.
In Most Cases, Attic Insulation Does Not Need To Provide A Vapor Barrier. The good news is that blown-in insulation should not need a vapor barrier. Blown-in is primarily used on the attic floor, and vapor barriers are not a concern for attics in our climate zone.
Not to be confused with a vapor barrier—which is placed on the warm side of the wall just in front of the insulation and behind the drywall— a moisture barrier goes against the basement wall and behind the insulation and framing.
Water vapour diffusion through building materials accounts for only about 2% of moisture penetration through walls, and a vapour retarder primer can be twice as effective as it needs to be.
Water Vapor Permeability: To limit the possibility of mold and rot, house wraps that offer certain levels of vapor permeability are usually best. Look for products rated at 1 Perm (US rating) or 60 Ng (Canadian rating), as these are benchmark permeability rates for what defines a type II residential vapor barrier.
Depending on where you live, the vapour barrier will either go on the inner surface of the insulation (if you live in a cold climate) or the outer surface of the insulation (if you live in a hot climate). It's safe to say that a vapour barrier will be needed for almost all projects.
Aluminium foil is considered to be very resistant, tear- resistant and vapour diffusion-tight. A PE-aluminium laminated vapour barrier is particularly suitable for a vapour-tight construction.
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.
Foil-faced insulation can be used in very specific situations such as: Pitched roof – between rafters creating vapour barrier and preventing moisture build up. Ceiling - between floor joists where it acts as a sound transmission barrier.
Vapor barriers are installed along, in, or around walls, ceilings, and floors. Of course this is done to prevent moisture from spreading and potentially causing water damage.
All attics — vented or unvented — should have an air barrier (a properly detailed airtight drywall ceiling, for example) regardless of climate. Omitting a ceiling vapor barrier by arguing that "you have to let the moisture escape" or "because the house has to breathe out the top" is actually correct, in a way.