Open Cell Insulation Vapor Barrier

Open cell foam insulation is a porous material that can allow air and moisture to penetrate the insulation.

Open cell insulation vapor barrier.

So if you re considering spraying foam to the roof deck of your new or existing home you want open cell. Closed cell foam insulation is non porous with all of the voids closed to each other which makes it difficult for water vapor and air to pass through it. Open cell foam is not a vapor barrier so it allows the water from the roof leak to weep through the foam to the space below so it is the better choice for most residential applications. If there s a roof leak water will pass through the foam and you will quickly be able to find your problem.

R value at 1 3 7. Vapor barrier vapor permeability. There are three classes of vapor barriers. Open cell spray foam is not a moisture vapor barrier and will allow moisture to pass.

Spray in insulation and air barrier material. In most applications the buildings energy performance will be the same regardless whether you used open or closed cell foam. Closed cell foam has a much higher r value than open cell foam about r 6 5 per inch and it s a vapor barrier as well as an air barrier. Open cell needs a class ii vapor retarder old term barrier only in certain climates not all.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. Scientists still discuss if those methods are efficient. Foam insulation porosity vapor barrier issue. When an area is accessible for maintenance or repair then any foam must have an ignition barrier over the foam or an equivalent material such as properly tested and listed intumescent coating matched to the type and brand of foam or it must be.

Open cell spray foam closed cell spray foam. Not every type of insulation needs a vapor barrier. Ft and it s unaffected by water. Vapor barriers sheets of plastic or kraft paper keep water vapor out of the wall cavity so the insulation stays dry.

One manufacturer demilec says its heatlok high lift spray foam has an even higher r value r 7 5 per in closed cell foam is much denser about 2 lb. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. For example closed cell foam is from class ii and open cell is from class iii. Not every wall does.

Structural reinforcement able to deflect water and reject bulk water able to accommodate seasonal shifting.