Roof Venting With Spray Foam Insulation

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

Roof venting with spray foam insulation.

However many people think that roof vents cannot be used in conjunction with spray foam insulation. But today i m focusing on roofers because of something i saw recently. They could be in any trade really insulation hvac drywall. Roof vents are great for allowing air to move and for removing toxic odours from the home.

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. These are the home performance contractors green builders and spray foam insulation contractors. Attic ventilation and spray foam don t mix.

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. 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. Spray polyurethane foam is a chemical product that is created by two materials isocyanate and polyol resin that will react with each other when they are mixed and will expand up to 30 to 60 times its liquid volume as it is sprayed in place. 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.

Spray foam insulation can even be applied with roof vents. Rigid foam and spray foam are two of them. All insulation materials require proper venting. This alternative to traditional building insulation fiberglass can be applied into wall cavities holes concrete slabs and even onto roof tiles and.

Some are in the latter camp.