Spray Foam Flat Roof Ventilation

The movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system.

Spray foam flat roof ventilation.

Similarly not everyone can afford to spray nearly 10 in. We have the capabilities to spray and inject a variety of foam systems to achieve a high r value while providing both effective vapor and air barriers. Using closed cell spray foam insulation to fill the cavities and have ventilation throughout the roof will give you roughly an r 31 5. Since ccspf is a vapour retarder some believe it cannot be used in warm humid climates as it prevents water vapour from going in and out of the assembly.

At ifspray we have a spray foam insulation system with special ultimate linings for flat roofs. Of open or closed cell spray foam in their roof or to stack a half foot of rigid foam on the roof deck. Closed cell spray foam has a perm rating of approximately 1 5 to 3 0 per 25 mm 1 in and an r value of approximately 1 05 per 25 mm 6 0 per 1 in. The spray foam solution is a complete vapour barrier which immediately prevents leaks as well as keeping.

However many people think that roof vents cannot be used in conjunction with spray foam insulation. An alternative option is to insulate the rafter bays with a less expensive insulation like fiberglass or cellulose and to control the temperature of the roof sheathing with rigid foam. But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used. However using closed cell spray foam negates the need for ventilation at all and will operate better if you simply do not ventilate the roof and have closed cell spray foam insulation installed.

Spray foam insulation can even be applied with roof vents. Unvented flat roofs a technical discussion flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. Froth pak 620 sealant 2 component foam insulation kit a tank b tank 30 hose closed cell quick cure polyurethane expanding spray foam 3 9 out of 5 stars 16 759 00 759. Roof vents are great for allowing air to move and for removing toxic odours from the home.

However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options.