Arizona Roofer

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Improper cementitious “C-cure” roof application

July 23rd, 2009

What is a Cementitious roof ? Or also known as C-cure. C-cure is a light weight Cementitious concrete that is spray applied over a polyurethane foam roof. It is one of the most expensive foam roofs you can buy. The  c-cure has a very high fire rating and is usually applied on schools, government buildings, high traffic roofs or anywhere you need a fire rating.

I was on one recently and took some pictures. The foam application part of the roof is just about as good as they come, but Cementitious part of the roof is as bad as they get.

The application of a Cementitious roof is as follows:

1. Polyurethane foam is applied at a thickness of the roof spec. usually @ 1 1/2 inches or greater.

2. An elastomeric roof coating is applied @ about 1 gal. per 100sqft.

3. A second coat of elastomeric roof coating is applied @ 1.5 gal. per 100sqft. At this time a #6 Aggregate is applied into the wet coating @ the rate of about 35-40lbs per 100sqft.

4. All verticles ”anything above the roof surface” walls, pipes, a/c curbs t-tops ect.  are coated with an elastomeric coating.

5. Finally the C-cure is applied over the roof surface. It’s applied in both directions to prevent voids. The dry thickness is 1/4 of an inch. The finished surface should have a smooth apperance with only the top of the aggregate visable.

Below are some pictures of an inproper c-cure application that will lead to premuture roof failure. Also pictured are incorrect repair methods.

Failed c-cure roof due to improper application

Failed c-cure roof due to improper application

Popcorn Looking c-cure roof

Popcorn Looking c-cure roof

This next picture shows a repair done using an elastomeric roof coating. Elastomeric  coating will not stick to c-cure so thats why this repair has failed.

Elastomeric coated c-cure repair

Elastomeric coated c-cure repair

This next picture shows a c-cure repair done using an aluminum roof coating. You can’t use this coating on a c-cure roof.

You can't use aluminum roof coating on a c-cure roof

You can't use aluminum roof coating on a c-cure roof

What happens now?

This deficiency was discoverd during a roof inspection. Good for the owner because the roof  has not yet completely failed. The bad news is a $15000 c-cure recoat 10 years early. The bottom line here is had the building owner used a roofing consultant to over see this roof installation he wouldn’t have the problem he now has. This is more common than you might think.