Spray Foam Insulation Attic Ventilation

High attic humidity often results from spray foam insulation.

Spray foam insulation attic ventilation.

Earlier this year i got a question about a home that had spray foam insulation in the attic. Nothing unusual about that. 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. What you re looking at there is the place where a power attic ventilator had been.

The unvented attic space is considered the most effective and up to date building practice particularly by the spray foam industry. Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e. Unvented attics sometimes called sealed enclosed or encapsulated attics feature insulation on the underside of the roof decking rather than on the attic floor. Heat from the house rises up to the attic but when there isn t one the heat rises up to the roof.

Class i e 84 fire retardant meets building code spec. Rigid foam and spray foam are two of them. Spray foam insulation that s convenient and easy to use. 100 free of cfcs vocs penta bdes urea formaldehyde.

This alternative to traditional building insulation fiberglass can be applied into wall cavities holes concrete slabs and even onto roof tiles and. The best attic insulation. 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. The most important thing to remember is to use the correct type of insulation and to ensure it is installed correctly.

Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t any attic space. If a blower door test reveals that your spray foam insulation reduced ventilation beyond an acceptable level you may need to install one of these units in your home. Use closed cell foam it green for attic rafters. R value of 7 in 1 inch 97 closed cell foam.

All insulation materials require proper venting. 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. 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.