Attic Venting With Spray Foam

Unvented attic space the unvented attic space is considered the most effective and up to date building practice particularly by the spray foam industry.

Attic venting with spray foam. Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space. From a design perspective attic venting is not provided to address roof leaks. The basic design assumption regarding all roofing systems is that the roof system deflects water away from moisture sensitive materials. But then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents.

To add to what brian said closed cell spray foam ccspf applied directly to the underside of the roof sheathing would seal a ridge vent shut. The two products most often used in an unvented attic assembly are medium and low density sprayed polyurethane foam spf. One huge benefit of the spray foam insulated attic is that conditioned air leakage from the ac furnace duct system is contained and used to condition the attic. They also need to seal off areas of air leakage to the outdoors.

Gable vents and soffits are the big culprits here. An open cell foam low density spray polyurethane is a spray applied to provide continuous insulation and an air sealing barrier. When you use it instead of the fluffy stuff fiberglass cellulose cotton a house will be more airtight. If it does not do this it has failed.

Otherwise humidity will quickly creep into your attic. Rigid foam and spray foam are two of them. This spray foam is applied as a low or high pressure two component polyurethane spray foam that can be applied onto walls in unvented attics to ducts and ceilings and in vented attics and crawl spaces. Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof.

Unvented attics sometimes called sealed enclosed or encapsulated attics feature insulation on the underside of the roof decking rather than on the attic floor. Spray foam insulation performance can offer different ways to address problematic situations. All insulation materials require proper venting. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits.

Most installations of spray foam insulation when properly installed act as an air barrier. However in a traditionally insulated attic insulation on the ceiling the attic is vented. When a house is airtight the nasties in the indoor air tend to stick around. You don t need soffit or gable vents either since the attic is now conditioned space.

In a proper spray foam job a contractor doesn t just spray foam all over the top of your attic and go home.