A Foam-Based Solution For Flat Roofs
This week let’s discuss a foam-based solution for flat roofs. Many homes in the southwest feature flat roofs, also known as “pueblo style.”
Before we go any further, we need to clarify what we mean by “flat” roofs. The frame of a flat roof will typically incorporate some slope. A roof with a slope of less than three inches to one foot is considered flat. Water does need to run off this type of roof, so a minimum slope of one-quarter inch per foot will be built in. Many roofing materials are available that will waterproof a flat roof. One of them is foam roofing.
Tim Forstie of Durafoam Roofing LLC explains how and where foam roofing works best.
Why Foam Roofing?
Tim tells us “the primary reason to use foam is the insulation factor it provides”.
- For every inch of foam roofing, you will add an R-value of 6.5 to 7 to the insulation of your roof. Most foam roofs are done using at least one inch of foam. If you want a better insulation value, add additional thickness.
- Foam is self-sealing. The product adheres to surfaces well, creating a tight water barrier for your home.
- Foam roofs are also self-flashing, which means the top layer of the roof does not need fasteners, adhesives, or rocks secured to the insulation or deck below. Roof penetrations such as pipes and ductwork don’t require specialized flashing systems. The foam seals around them.
Installing A Foam Roof
As you may suspect, the foam installation process differs from shingle or tile roofing.
- The foam is sprayed as a liquid in quarter-inch to one-half-inch passes as necessary to achieve the desired depth.
- The foam rises and dries in about one minute.
- If the roof is not constructed with a slope, then the foam can be applied in varying thicknesses to promote water drainage.
The surface that the foam is applied to, known as the substrate, can be any surface that is not blistering, peeling, rotting, or otherwise damaged. Removal or repairs to that subsurface need to be made first.
- If existing roofing needs to be torn off and the wood deck is in good condition, the foam can be applied directly to the wood decking. Underlayment is not required.
- If the existing roofing is not damaged, the foam can be applied directly over it.
- With new construction, foam is installed directly over the roof deck.
Parapets
Most homes with flat roofs will have a parapet wall around the perimeter. Often, cant strip is needed for fabric roofing to transition from a horizontal to a vertical surface. The cant strip is a piece of solid material that creates a 45-degree angle instead of a 90-degree angle and is not needed for foam roofing. Initially applied as a liquid, the 90-degree angle is not a problem and, unlike fabric roofing, this point on the roof is not a stress point for foam.
Tim tells us that his crew often finds that stucco homes have stucco applied on top of the parapet wall. This stress point in the stucco is often cracked and causes leaks. Foam is applied directly over the crack after loose material is removed. This negates the need for costly stucco repairs.
Slope
Let’s get back to the slope. We all know that getting the water off the roof is the goal. When a flat roof does not have a slope built into it, Tim tells us the foam can be applied in varying thicknesses to create one on most roofs. Starting in the middle or where the roof abuts a wall, applicators start with a three to four-inch thickness and taper to one inch at the roof’s edge or at the scupper.
Where the thickness is insufficient, applicators will create a series of slopes and channels to facilitate water flow off the roof.
Protecting the Foam
Like most materials, foam is susceptible to damage by UV rays of the sun. For protection, multiple layers of a UV-resistant coating are applied over the foam.
White is the most common coating color. White helps reflect the hot sun rays, adding to the positive effect of the insulation.
Because some HOAs do not allow white, an off-white or beige color can be added to the coating mix.
Maintaining A Foam Roof
As with all aspects of your house, home, castle, or cabin, there are some steps you need to take to protect your roof.
The most common is accumulation of debris from trees. Leaves falling on the roof can block scuppers, causing water to pond.
After a storm blows through, check your roof. Minor hailstorms are typically not a problem, but branches blown onto the roof can be a big one.
Foam Roof Warranties
Tim tells us that there are basically two types of roof warranties, a five-year and a 10-year. Both are based on time. The difference between them is the number of coats of protection applied. Each coat is about 10 to 15 millimeters thick.
- A 5-year warranty will have two layers of the protective coating, providing 20 to 30 millimeters of protection.
- A 10-year warranty will have three layers of protection, providing 35 to 40 millimeters of protection.
The reason for the timing has to do with the fact that your roof will lose roughly one millimeter a year. When the roof coating gets below 10 millimeters, the UV rays begin to deteriorate the foam.
Foam roofing can be a great roofing material for new and re-roofs. With re-roofs, the foam can hide and protect against many flaws without extensive repairs before application.
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CONTENT PARTNER | Durafoam Roofing
A Rosie on the House Certified Partner since 1996! Since 1989, Durafoam Roofing has been providing top-quality solutions for home and commercial building owners in the area. We are a family business dedicated to delivering high-quality workmanship and providing the best roofing systems in Arizona. We are highly-trained experts in all types of commercial and residential roofing styles and materials. Our goal is to make sure your home or business roof exceeds your expectations.
PODCAST
Thick, bonding foam roofing for flat roofs does more than protect against the elements. It provides effective insulation that can reduce your energy bills year round. Tim Forstie of Durafoam Roofing discusses their process of foam application from preparation to routine maintenance. Its one of the best ways to protect your flat roof! (which isn’t truly flat)
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