Spray Foam Attic Vent

All insulation materials require proper venting.

Spray foam attic vent. The unvented attic space is considered the most effective and up to date building practice particularly by the spray foam industry. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. Nothing unusual about that. Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials.

Rigid foam and spray foam are two of them. Nope you absolutely do not need to ventilate a spray foam house and here s why. 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. Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e.

What you re looking at there is the place where a power attic ventilator had been. Wood has an r value of about one per inch of thickness. This is not an issue specific to spray foam as much as it is a characteristic of peel and stick membranes. Because basically now that attic is a conditioned space.

If spray foam is used a vent space may still be needed directly under the roof deck. Attic ventilation and spray foam don t mix that photo above is from an existing home that had spray foam insulation installed in the attic over the master bedroom. 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. Earlier this year i got a question about a home that had spray foam insulation in the attic.

Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. A lot of builders and homeowners are going with spray foam insulation because of the airtightness benefits but then the questioner mentioned that the spray foam contractor had intentionally left big holes to the outside by not sealing the gable vents. It s terrific because it s pretty much the same temperature as the rest of the house all the time. Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space.