Roof Ventilation With Spray Foam

Leave a gap on both sides.

Roof ventilation with spray foam.

How to vent a foam insulated roof step 1. This type of spray foam offers the specific benefits of continuous insulation interior wall cavity fill and unvented attic applications. That means you get rid of all attic ventilation whether it s passive ridge gable soffit vents or active fans. Actually you should probably get rid of power attic ventilators whether or not you re sealing the attic but that s another article.

One of the biggest benefits of using spray foam is to get greater airtightness. Spray the foam. Temporarily secure long plastic forms between the rafters on the inside of the ceiling. That is now a conditioned part of your house just like any room in your house.

These forms are only 1. But with spray foam ventilation is not an issue. Now we use attic ventilation when we use products like fiberglass because we have to manage the moisture. Mark bomber s book spray polyurethane foam in external envelopes of buildings reports on research that demonstrates ccspf under typical building conditions i e.

This is not an issue specific to spray foam as much as it is a characteristic of peel and stick membranes. It also reported the air sealing qualities of the foam were retained. When installed over wood framing that has 28 to 35 per cent moisture content took approximately 35 days to dry less than 19 per cent moisture content compared to 8 5 days to dry with no foam attached. If spray foam is used a vent space may still be needed directly under the roof deck.

Build the rafters and secure the 5 8 inch cdx sheathing material. The point i m making here is that a sealed attic should be well all sealed up.