Most authorities now agree that vapor barriers are important under certain conditions but not necessarily as a whole house solution for every home.
Spray on vapor barrier insulation.
A common misconception is that all insulations require vapor barriers in all situations.
Not every wall does.
After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.
Research has shown that this is incorrect.
Moisture barriers are specifically designed not to be a vapor barrier as the minimum water vapor permeance for a water resistive barrier is 300 perms.
Resolution of the vapor barrier debate.
If you need a vapor barrier and your insulation is unfaced you must cover it with a polyethylene film.
In circumstances where conditions inside a home or office are much different than outdoor conditions water.
There are three classes of vapor barriers.
Many of them don t agree that vapor barriers are so necessary even with open cell foam insulation.
In mixed climate areas the vapor barrier is optional depending on the total design of a building.
They are combined with flashing and other materials to ensure that there is a shingled assembly to direct liquid water.
Moisture barriers should be installed on the cold side of the insulation.
Map is divided into 7 climate zones every of which has its own requirements to the barrier class.
Cima does not recommend the use of vapor barriers with cellulose insulation except in circumstances of exceptionally high moisture levels such as an indoor pool facility or very cold climates.
Some debate still occurs over how necessary vapor barriers are but a consensus is growing closer.
In cold climates a vapor barrier is almost always needed.