Spray foam insulation and elastomeric roof coatings go together by lowering energy cost:
High aged R-value (depending on Manufacture R-value of 6-6.5)
Most roof coatings are light colored which helps reduce internal building heat
Reduces or eliminates thermal bridging
Reduces land fill by reducing future tear off and replacement
Spray foam insulation requires protection from the sun's ultra-violet radiation
and the elements. These elastomeric spray roof coatings protect and seal the
spray foam insulation from these elements.
Once the spray foam roof is applied, it has an elastomeric roof coating sprayed down which creates a protective layer. This protective layer produces a durable weather resistant surface that can be walked on for routine maintenance of other components located on a roof.
Below are the most common elastomeric roof coatings used over spray foam insulation?
Acrylic
Silicone
Urethanes
Polyurea
Crushed Rock (Look on the Portfolio of jobs tab, under rock Spray Foam)
Yes, crushed rock spread over the spray foam insulation is a successful system;
however, elastomeric roof coatings are more common. Elastomeric roof coatings are
spray applied as a single component, or in some cases plural component. The above
list of elastomeric roof coatings all have different physical properties and vary
in cost.
Roof coatings are usually installed as a base coat followed by a top coat. Granules
can be embedded into the final coat which adds an added protection against UV
light, light roof traffic, birds, and hail resistance.
In time, these coatings will require maintenance or recoating. Once these elastomeric
roof coatings are recoated, the warranty can be renewed as well. The average life span
between recoats is fifteen to twenty years.
A spray foam roof, like most other systems, will expand and contract during different
climate conditions. It is very important that the protective elastomeric roof coating
expand with the spray foam insulation, or damage will occur in the form of cracks
or delamitation. Physical characteristics, of elastomeric roof coatings such as elongation
and tensile strength are something you, the consumer, should take in great consideration
when picking the right elastomeric roof coating.
The use of roof Coating in the Midwest
Silicone
Pros of Silicone roof coatings: These roof coatings are often used along the coast where the humidity is high and hail is of little concern. Silicone roof coatings need water to cure, thus the high humidity helps them set faster. If it were to rain shortly after coating, silicone would quickly cure, where other coatings would wash off. Silicone roof coatings also can be applied at/or below freezing, which cannot be done with some other roof coatings. Silicone roof coatings also have a high wear resistance. This means that in ten years, little to no wear is found.
Cons of silicone roof coatings: Hail in the Midwest is a concern and can easly harm a silicone roof. Because of the chemistry, these coatings usually have low tensile strength and are not very hail resistant. If silicone is punctured, the roof has to be recoated with more silicone. Some silicone will not stick very well to a new coat, unless treated with a special cleaner.
Urethanes
Pros of urethane roof coatings: Urethane coatings are tough against hail because urethanes have a high tensile strength. They can be applied in cold temperatures and, therefore, give longer application windows. These roof coatings come in chemical or moisture cure, so humid environments don't make it hard to application.
Cons of Urethanes roof coatings: Urethane coatings tend to have a higher cost. Some of these coatings put off an odor that can linger in the application area.
Polyurea
Pros of Polyurea roof coatings: These coating are some of the strongest coatings on the market. Along with strength, they have a very low wear rate. Polyurea roof coatings are chemical resistant and corrosion resistant.
Cons of Polyurea roof coatings: A specific plural component machine is needed to create polyurea coatings. If the surface is not prepared correctly, the coating is more likely to delaminate from the substrate. A true white colored Polyurea is hard to form, and the coating tends to yellow over time.
Acrylic
Pros of Acrylic roof coatings: Acrylic is the middle of the road coating and is the coating of choice for Midwest contactors. Acrylic roof coatings are less expensive and easier to apply than others. Acrylic roof coatings, if applied thick enough, can handle most hail in the golf ball size range.
Cons of Acrylic roof coatings: Since Acrylic coatings are water based, they can wash off, if not dry, before rain. Acrylic roof coatings can take hours to dry in low heat, low wind or high humidity. Cheaper acrylic coatings don't last as long as other coatings and can become brittle and delaminate, especially in a bad hail storm.
