Polyurethane Foam Installation


The main component is polyurethane foam. This originates as a two-part liquid system which mixes in the spray nozzle. Chemical reaction starts immediately and as the mixed liquid hits the deck it rises (like yeast) and solidifies. Spray applying the foam at parapets and projections results in a monolithic membrane in areas that are usually troublesome, potential leak points, providing an absolute water-tight seal. Drainage can be built-in by adjusting the foam thickness.

Foam is non-intracellular which means each foam cell is a complete “bubble”, unlike a sponge where all the cells are connected. This means, if the foam is punctured it will not soak up moisture.

If polyurethane foam is exposed to sunlight it will “rust” or degrade from the ultraviolet light. A coating is applied to prevent this. This protective coating is the principle maintenance item on a foam roof.


Several coatings are compatible with foam. Acrylic and silicone are used most frequently. the coating is spray applied to the specified thickness, usually in more than one application. The first coat is commonly a darker color so coverage can be easily monitored. The top coat is normally white, although pigmented coatings are available.

The integrity of the coating must be checked every 5-7 years and touched up as necessary.

Foam roofs can be walked on, but the surface is more susceptible to wear from foot traffic than a built-up roof. Granules can be applied for added surface protection by broadcasting them into final coating application while wet. It is also advisable to install walk pads from the roof access to where maintenance will be done of roof-mounted equipment.

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