Spray Foam Underside Of Roof

The spray foam can also serve as the thermal and vapor control layers in both new and retrofit construction.

Spray foam underside of roof.

I have a conditioned attic currently insulated with r19 fiberbatts between the rafters. Should i put any membrane or the like on the underside of the roof sheathing before spraying the foam in. When the choice is made to insulate along the underside of the roof deck spray foams have advantages over other insulation types because of the ability of spray foams to effectively air seal complex assemblies. Thanks for filling in the missing details.

This construction approach was first used in the 1970s and it has been implemented much more widely since it was first included in the international code council s icc model building code in 2007 irc section 806 4. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Closed cell foam also contributes additional rigidity to the roof while remembering our minimum safety assumption. Open cell spray polyurethane foam ocspf and closed cell spray polyurethane foam ccspf insulation sprayed to the underside of roof sheathing is a popular strategy for increasing roof insulation levels in all climate zones.

The roofing materials are installed and consist of timberline shingles and full coverage ice and water barrier the entire roof. This is important because you do not want water vapor within the foam condensing at the juncture where it contacts the metal. I m constructing a new home along the rhode island shore. Closed cell foam is a vapor retarder while open cell is more vapor permeable.

When it comes to spray foam insulation that is applied to the underside of the roof between the rafters the financial benefits are even more impressive with the initial outlay recouped within just a few years on average. As i m sure you know 8 inches of closed cell spray foam is neither cheap nor particularly green but in your circumstances the spray foam may make sense. Watch this video on youtube. Yes you can spray foam the underside of your roof.

Moisture generated indoors or that infiltrates into the home is responsible for the bulk of the moisture in an attic insulated with spray foam on the underside of the roof sheathing. The attic is unvented for instance no ridge vent exists. The attic will be a conditioned space and i m planning to apply spray foam insulation to the underside of the roof sheathing. No airsealing hence i want to remove the fiberbatts and spray 3 inches of closed cell spray foam in before putting the fiberbatts back in place.

It s not coming from above the roof and it s not some new moisture source resulting from the spray foam. Installing the baffles will provide a better installation than spraying directly against the underside of the roof sheathing. You can spray foam anywhere you d like to separate the inside from the outside.