FAQ for Architects, Specifiers, and Builders

Question:

I am in the planning stages of building a poultry house and due to the high cost of metal roofing I would like to know if there is a inexpensive way to spray foam the roof instead of metal. I understand spray foam is used extensively on flat commercial roofs but would this same product be able to be used on a low slope agricultural structure with limited substructure?

Answer:

You can apply SPF roofing on top of most substrates and is not limited to low slope commercial buildings. A complete system with a UV protective coating is very lightweight. Most likely, SPF roofing would be perfect for your application. Let me know if you have any other questions.

Question:

Answer:

Normally, spray polyurethane insulation is installed at the same point in the construction cycle as other types of insulation. That is, using traditional building techniques, spray foam should be installed after the rough plumbing, electrical wiring, and heating and air conditioning ducts have been installed. If you decide to seal the entire exterior shell with spray polyurethane, spray insulation may need to be applied in some areas before the ductwork is installed.

Question:

Can spray polyurethane insulation be applied directly to electrical wiring? What about installed electrical devices like recessed lights?

Answer:

Spray polyurethane foam can be applied directly to electrical wiring. Recessed lights or other fixtures may require a certain amount of air circulation around them for cooling purposes. In these cases, a box can be build around the fixture with gypsum wall board; then spray foam can be sprayed directly to the outside of the box.

Question:

Have any fire-rating tests been performed for Gaco 183?

Answer:

You'll have to contact Gaco Western for that information. I'm sure they would be happy to help.

Question:

How does closed-cell spray foam provide moisture protection, yet still breathe?

Answer:

Unlike cellulose and fiberglass materials, closed-cell foam is impervious to water penetration and wicking. Yet, like Gortex® fabric, the closed-cell structure allows the diffusion of water vapor (high energy particles) to permit your building's envelope to "breathe". Liquid water has much larger structure and is unable to pass into or through a closed-cell foam barrier.

Question:

How does spray polyurethane insulation seal my building?

Answer:

Spray polyurethane insulation is sprayed on as a liquid which reacts and expands in place. This expansion action also seals all of the cracks and crevasses in your wall's exterior sheathing. The result is that air can no longer slip in: your building will be less drafty and more comfortable. Air leakage can also introduce moisture into the wall cavity, resulting in wet insulation and mold and mildew. With the sealing effects of spray polyurethane foam, this will not be a concern

Question:

How much does spray foam cost?

Answer:

I'm afraid this question is difficult to answer without more information. Especially in roofing, there are a lot of variables, beyond just the cost of the material, that go into creating a SPF roof. You need to contact one of the SPF suppliers advertised on Sprayfoam.com or contact a local SPF roofing contractor to get an estimate

Question:

Is spray polyurethane insulation code approved?

Answer:

Yes. Building codes provide for the use of spray polyurethane insulation in the Foam Plastic section. This section of the code also describes the use of thermal barriers.

Question:

Won't sealing my building with spray polyurethane foam lead to indoor air quality problems?

Answer:

Your building does need to be ventilated in order to maximize the quality of indoor air (moisture levels and contaminant levels). Most design professionals will advise you to seal the structure as tight as possible and provide the necessary ventilation through the heating and air conditioning system. Many systems employ a highly energy efficient "air exchanger" which is designed to pre-condition (either warm or cool) the incoming outside air with the outgoing exhaust air. In this manner, you can build an extremely energy efficient exterior shell using spray polyurethane foam while still providing controlled and energy efficient ventilation.

Question:

Building a new addition I am am planning on foaming the entire house. Going to use a cedar roof. Should I put the cedar roofing on plywood and attach a rain breather then roofing or can I just put roofing on slats and spray right to roofing material?

Answer:

The building code in unvented attic section 2012 R806.5 or 2009 R806.4 states that wood shingles or shakes should have a minimum 1/4 inch vented air space between the shake and the roofing underlayment. Spraying directly to the underside of shakes is not recommended per this code