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How Much Does Foam Roofing Cost?

Foam roofing offers a fast way to increase the insulating ability of the roof deck. The high R-value means that spaces such as attics or bedrooms can have more ceiling height by not requiring additional insulation in the trusses or rafters to condition the space. The conditioned space also reduces the amount of drafts from hot and cold spots. The foam stays in place, and the R-value will not change over the years.

See all the costs associated with foam roofs below.

The Costs 

  • Minimum costs: A basic foam roof installation costs approximately $3 per square foot based on standard R-value ratings and common roof construction.

  • Maximum costs: Additional complex roofing and higher R-value foam cost up to $5 per square foot.

After calculating material and labor expenses, additional costs are related to the specific coating requirements for foam. The cost can increase by a third when adding coatings for environments with longer solar cycles. Environments closer to the equator have more intense proximity to solar radiation and longer heat cycles. As a result, foam insulation may require a thermal break and special UV coatings on top of the standard coating for roof substrate sealing.

Spray foam coating comes in either acrylic or silicone coatings. The difference between silicone and acrylic coating is based on cost and viability to the area. A silicone coating may be installed directly over acrylic. These are short-term versus long-term costs to consider. Acrylic coatings can save a substantial cost in priming initially. Silicone coatings can increase long-term energy savings by over 30 percent. Many commercial applications will apply acrylic initially and then upgrade to silicone as time goes on or use a hybrid of the two to combine energy and start-up cost savings.

What is Foam Roofing?

Polyurethane foam roofing consists of a protective coat layer and a foam layer on top of a substrate. It's a simple combination of materials that differs greatly from traditional roofing in terms of time and expertise. Foam roofing is applied using a liquid chemical that expands to over 20-30 times the volume of the original liquid. A chemical reaction occurs between two liquids that combine in a pressurized tank to produce the expansion. Foam roofing can also use a reflective coating to act as an additional thermal barrier during hotter times of the year. The reflective coating is added after all sealers have been applied.

Foam does not require flashing material. The foam itself is self-flashing and dries in seconds upon contact. Spray foam creates a tight fight around these openings when applied directly to the substrate and opening. The proper thickness will need to be calculated for endurance and rigidity, and previous roof flashing will need to be removed to provide the best adherence to the roof deck. The lack of flashing costs can be calculated in the final product cost.

Polyurethane foam roofing is considerably more lightweight than traditional roofing material. In fact, foam can be walked on directly and can handle normal wear and tear. As a result, load calculations often allow for additional components to be stored on the roof deck and substrate. The lightweight nature of foam also means that there is no need for additional materials for roof sloping and pitch. The foam can be made to curve around joints for a waterproof membrane. 

Materials & Types of Foam Roofing

Cool roof coatings fall under the class of elastomeric coatings. These coatings protect the foam underneath and provide a painting surface. This creates an additional waterproof membrane that reduces heat infiltration on the roof. A cool roof coating may require several weeks of drying for additional layers of foam. The elastomeric coating also reduces the UV radiation from the sun that can cause foam to oxidize over time. All of these coatings can be applied at the same time as well.

Installation of a foam roof will require substrate preparation, coating and sealing. A foam roof cannot be applied directly without conditioning the substrate below. A clean, dry surface is prepared for contact, a process that includes the removal of any existing roofing material. The entire surface is primed with an adherence polymer to increase the adhesion of the foam product to the roof deck. This priming also prevents overspray from foam during the curing phase. 

Advantages of Foam Roofing

A traditional roof consists of several components. These components are usually a combination of flashing and underlayment for a moisture-proof barrier. Foam roofing uses all of these elements in one application. Closed-cell foam is a superior material for creating a strong water barrier and sealing against air drafts. There is no need for a felt underlayment or metal flashing against vent stacks or air conditioner units. 

A foam roof does not require the breakdown of individual tasks found in traditional roofing. These tasks often include waterproofing and deck insulation as separate processes to be completed before the roof material can be installed. A foam application combines all these tasks without the additional expertise in flashing experience or shingling. Smaller roofing tasks can easily be completed in one day. In the commercial world, this can increase productivity time towards other projects.

Disadvantages of Foam Roofing

A foam roof may require annual inspection and a recoating every 10 years or so. Other factors such as weather and wind erosion can affect the performance of a foam roof system. The skill of the installer is essential because incorrect application can be detrimental to the lifespan of the roof and substrate. 

An inexperienced installer may make mistakes that are difficult to fix with a closed-cell foam application. Spray foam is a unique roofing material that requires precision and an understanding of chemical reactions to create the desired uniform performance. The timing is also important. Another major drawback is applications that installation cannot be performed on rainy days or during cold and windy weather, which would result in overspray that can adhere to other parts of the roof site.

Last updated on Jun 17, 2014

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