Roof Ventilation With Spray Foam

This type of spray foam offers the specific benefits of continuous insulation interior wall cavity fill and unvented attic applications.

Roof ventilation with spray foam.

It also reported the air sealing qualities of the foam were retained. Open cell spray polyurethane foam or closed cell spray polyurethane foam ccspf insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in all climate zones see figure 1. Leave a gap on both sides. Actually you should probably get rid of power attic ventilators whether or not you re sealing the attic but that s another article.

In comparison to high density spray foam medium density spray foam is applied as a low or high pressure two component polyurethane spray foam. One of the biggest benefits of using spray foam is to get greater airtightness. Temporarily secure long plastic forms between the rafters on the inside of the ceiling. Build the rafters and secure the 5 8 inch cdx sheathing material.

Wood has an r value of about one per inch of thickness. Mark bomber s book spray polyurethane foam in external envelopes of buildings reports on research that demonstrates ccspf under typical building conditions i e. 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. How to vent a foam insulated roof step 1.

That means you get rid of all attic ventilation whether it s passive ridge gable soffit vents or active fans. 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. If spray foam is used a vent space may still be needed directly under the roof deck.

Spray the foam. The point i m making here is that a sealed attic should be well all sealed up.