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sun yu Posted: Aug 24, 2007 12:05 AM	foam roof with or without granules? i've noticed some companies spray foam and apply 2 coats over the foam and others opt to apply 2 coats and add granules. is it better to topcoat with granules? i wonder about the addtional weight- if placed on top of old tar/gravel roof and additional maintenence- harder to keep clean and additional cost to recoat- would require more/thicker coating and additional granules during recoats? the companies say it protects against birds pecking. how common is it to have birds pecking roofs though? i don't have roof access but do have problems with pigeons nesting in the gutters but have no ideal if they are pecking the roof. i live in los angeles, but far from the beach- no sea gulls on my roof. personally, would like to have foam without granules but do not want to regret/compromise the new roof. hoping to have polyurea coating- depends on the estimates but seems to provide the toughest coating. thanks.
mason Posted: Aug 24, 2007 08:02 AM	Granules are used most often with silicone and acrylic coated roofs to increase the impact and abrasion resistance of those coatings. It will require more coating to do it properly, typically about 3/4 gallon per square. Granules can protect to some extent against mild hail damage, excessive foot traffic, dropped tools, bird pecks and similar types of damage. It will not prevent impact damage just reduce its effect. A high tensile strength coating such as polyurea and polyurethane coatings can achieve similar or greater impact and abrasion resistance without granules, so you don't usually see those coatings with granules. However, in areas where high impact is expected, such as the hail belt area of Texas, Oklahoma, Nebraska, etc, extra coating is typically specified even with polyurethanes or polyurea coatings to add extra impact protection. As to the weight of the granules. Only a light coat of granules is used typically at a rate of 20 to 30 pounds per square. Two inches of foam covered with 3 1/2 gallons per square of coating plus 20 to 30 pounds per square of granules would only weigh about 75 to 85 pounds per square. In recovering an aggregate covered BUR with a sprayfoam roof, 500 to 700 pounds per square of aggregate is removed. So, the extra weight of the granules is not a significant factor. As to the bird pecking problem. Birds can be a problem for many roofing systems all over the country and not just on the coast and not just sprayfoam. For example, Kildees in West Texas have destroyed more than one BUR roof. They may ignore hundreds of roofs in a general area and concetrate on the one unlucky roof. My own recommendation, use either more coating and/or granules in areas where impact and abrasion resistance is expected and don't worry about the extra weight.

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sun yu

Posted: Aug 24, 2007 12:05 AM

foam roof with or without granules?

i've noticed some companies spray foam and apply 2 coats over the foam and others opt to apply 2 coats and add granules.

is it better to topcoat with granules? i wonder about the addtional weight- if placed on top of old tar/gravel roof and additional maintenence- harder to keep clean and additional cost to recoat- would require more/thicker coating and additional granules during recoats? the companies say it protects against birds pecking.

how common is it to have birds pecking roofs though? i don't have roof access but do have problems with pigeons nesting in the gutters but have no ideal if they are pecking the roof. i live in los angeles, but far from the beach- no sea gulls on my roof.

personally, would like to have foam without granules but do not want to regret/compromise the new roof. hoping to have polyurea coating- depends on the estimates but seems to provide the toughest coating.

thanks.

mason

Posted: Aug 24, 2007 08:02 AM

Granules are used most often with silicone and acrylic coated roofs to increase the impact and abrasion resistance of those coatings. It will require more coating to do it properly, typically about 3/4 gallon per square.

Granules can protect to some extent against mild hail damage, excessive foot traffic, dropped tools, bird pecks and similar types of damage. It will not prevent impact damage just reduce its effect.

A high tensile strength coating such as polyurea and polyurethane coatings can achieve similar or greater impact and abrasion resistance without granules, so you don't usually see those coatings with granules. However, in areas where high impact is expected, such as the hail belt area of Texas, Oklahoma, Nebraska, etc, extra coating is typically specified even with polyurethanes or polyurea coatings to add extra impact protection.

As to the weight of the granules. Only a light coat of granules is used typically at a rate of 20 to 30 pounds per square.

Two inches of foam covered with 3 1/2 gallons per square of coating plus 20 to 30 pounds per square of granules would only weigh about 75 to 85 pounds per square.

In recovering an aggregate covered BUR with a sprayfoam roof, 500 to 700 pounds per square of aggregate is removed. So, the extra weight of the granules is not a significant factor.

As to the bird pecking problem. Birds can be a problem for many roofing systems all over the country and not just on the coast and not just sprayfoam. For example, Kildees in West Texas have destroyed more than one BUR roof. They may ignore hundreds of roofs in a general area and concetrate on the one unlucky roof.

My own recommendation, use either more coating and/or granules in areas where impact and abrasion resistance is expected and don't worry about the extra weight.

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