Roof Venting With Spray Foam Insulation

Attic ventilation and spray foam don t mix.

Roof venting with spray foam insulation.

But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used. Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space. Spray foam insulation can even be applied with roof vents.

Attic ceiling to stop airborne moisture from reaching a cold surface and condensing inside the building envelope in this design insulation effectively separates the interior and exterior spaces while slowing down moisture flow so the dewpoint is not achieved within. Unless you re bulk filling rafter bays between 2 10 or 2 8 rafters with closed cell spray foam this approach will likely require you to fur out the rafters to accommodate additional insulation to achieve desired r values. Rigid foam and spray foam are two of them. The movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system.

However many people think that roof vents cannot be used in conjunction with spray foam insulation. For best performance the airspace in the vent chute should be a minimum of 2 in. These are the home performance contractors green builders and spray foam insulation contractors. This alternative to traditional building insulation fiberglass can be applied into wall cavities holes concrete slabs and even onto roof tiles and.

But today i m focusing on roofers because of something i saw recently. While fiberglass insulation is an excellent and effective product for insulating most building cavities in areas where there is extra risk of trapping moisture and thus rot or mold infections such as crawl spaces and cathedral ceilings where roof venting may be absent or minimal we prefer to use closed cell foam insulation products or spray. Roof vents are great for allowing air to move and for removing toxic odours from the home. All insulation materials require proper venting.

Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e.