Do You Need Attic Ventilation With Spray Foam Insulation

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

Do you need attic ventilation with spray foam insulation.

Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof. Becoming more affordable significant long term energy savings sealing restricts air movement through the building envelope. This alternative to traditional building insulation fiberglass can be applied into wall cavities holes concrete slabs and even onto roof tiles and. Oh and when you put it in your attic spray foam.

Rigid foam and spray foam are two of them. Now we use attic ventilation when we use products like fiberglass because we have to manage the moisture. That is now a conditioned part of your house just like any room in your house. 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.

Compared to traditional insulation whether fiberglass or cellulose spray foam has the potential to provide better performance via its air sealing properties high r values per inch of thickness and in the case of closed cell spray foam ability to repel moisture. Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space. 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. All insulation materials require proper venting.

Earlier this year i got a question about a home that had spray foam insulation in the attic. But with spray foam ventilation is not an issue. Nothing unusual about that. When we seal the attic with spray foam it s as tight as a butter tub.

You may not have heating ducts up there but it does not need to be ventilated. The most important thing to remember is to use the correct type of insulation and to ensure it is installed correctly. 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 foam insulation will not prevent ventilation and so there s no need to avoid it thinking that it will result in mould and mildew from building up inside the attic space.

However in a traditionally insulated attic insulation on the ceiling the attic is vented.