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.
What happens if you don’t use vapor barrier?
If water vapor diffuses or infiltrates into the wall cavity and finds the cool surface,
moisture problems
can occur. Of course, you can have moisture problems here even without the exterior vapor barrier because of what Bill Rose calls the rule of material wetting.
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.
Where are vapor barriers required?
A vapor barrier is likely required
if the building is cladded with absorptive material
and if the structure is in United States climate zones 4C, 5 through 8. If you are building in a colder climate, check local laws or consult with your architect if a vapor barrier is required.
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.
Can I use plastic sheeting as a vapor barrier?
In simple terms, a vapor barrier is a material that won’t allow
moisture
to pass through it, such as plastic sheeting. A very simple experiment to show how a vapor barrier works is to lay a plastic garbage bag down on some damp soil. … There are two basic types of vapor barriers used with exterior wall insulation.
Should you put plastic over insulation before drywall?
Normally interior walls do not require a vapor barrier, but there are some situations where it is highly recommended. … A
continuous plastic
vapor barrier behind the drywall will protect the interior walls of these areas from water damage.
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.
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.
When should you not use a vapor barrier?
You may find that vapour barriers are
often not required in warmer climates
. And, if installed in the wrong climate or on the wrong side of building materials, a vapour barrier can cause more harm than good. This circumstance may prevent water vapour from drying, which in turn can cause rot and mold. (Source: Dupont.)
What qualifies as a vapor barrier?
A vapor barrier (or vapour barrier) is
any material used for damp proofing
, typically a plastic or foil sheet, that resists diffusion of moisture through the wall, floor, ceiling, or roof assemblies of buildings to prevent interstitial condensation and of packaging.
Is vapor barrier required by code?
A vapour barrier is required by the
National Construction Code (NCC) Volume Two under slab-on-ground construction
for all Class 1 buildings and Class 10 buildings where the slab is a continuation of the Class 1 slab.
How much does it cost to have a vapor barrier installed?
An average vapor barrier installation costs
$2 to $4 per square foot
or between $1,200 and $4,000 for materials and labor. *Labor costs to install add $1.50 to $3.00 per square foot on average.
What kind of plastic do you 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.
Can I use Tyvek as 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.
