Spray Foam Attic Roof

If you look closely you ll see two exhaust flues on the left side.

Spray foam attic roof.

One huge benefit of the spray foam insulated attic is that conditioned air leakage from the ac furnace duct system is contained and used to condition the attic. The installer sprayed foam directly on the metal flues. It will also help keep any duct leaks within the conditioned space of your attic. An attic that is properly vented has 50 intake of fresh air and 50 exhaust of the hot air.

Most people do not realize the requirements for proper venting of an attic. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials. When spray foam is installed on the underside of the roof deck the attic space is insulated from heat that otherwise would be entering the attic.

Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. If you do not have proper ventilation you are in essence cooking your shingles. This will allow for optimal operation of your hvac equipment as well as aid in early detection of situations such as roof leaks and wind driven moisture intrusion. The attic you see in the photo here is a different home but it does have one feature in common besides the spray foam.

Using icynene spray foam as your attic insulation will turn your attic into a conditioned space. You should never do this. 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. It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.

The insulation reduces wildly high temperature spikes and so the attic becomes a conditioned part of the home like any other room. Lstiburek takes blame for bad language. It s important you spray foam attic rafters only if you need to. Consumers are often told by spray foam contractors to do the rafters.

It s quick and easy to do. Using spray foam insulation in an attic is a popular energy saving project. Sealing the top of the house keeps the air you paid to heat and cool inside your home. You ll also see another safety hazard and code violation.

The main concern with spray foam insulation and shingle warranty is proper attic ventilation. In a vented attic all of that expensive airflow is lost to the environment. If you re using the attic for living space then you need to insulate the rafters. When we seal the attic with spray foam it s as tight as a butter tub.