Roof Ventilation With Spray Foam

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.

Roof ventilation with spray foam.

It also reported the air sealing qualities of the foam were retained. These forms are only 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.

How to vent a foam insulated roof step 1. Spray the foam. If spray foam is used a vent space may still be needed directly under the roof deck. In comparison to high density spray foam medium density spray foam is applied as a low or high pressure two component polyurethane spray foam.

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. Wood has an r value of about one per inch of thickness. Build the rafters and secure the 5 8 inch cdx sheathing material. 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. Temporarily secure long plastic forms between the rafters on the inside of the ceiling. This type of spray foam offers the specific benefits of continuous insulation interior wall cavity fill and unvented attic applications. One of the biggest benefits of using spray foam is to get greater airtightness.

This is not an issue specific to spray foam as much as it is a characteristic of peel and stick membranes. Leave a gap on both sides.