Silicone roof coating expansion and contraction

Here is a lesson learned about instilling a coating system in cold temperatures:

This 5 Layer silicone roof coating system installed on a 20 year old built up roof with an aluminum coating on it. The roof was properly power washed and preped before the installation. There is an epoxy prime base coating sandwiched between a special mesh fabric for added strength. Then there is a 60 wet mil layer of high solid silicon for the final coat. This system should be bombproof, but there were a few things done wrong with the installation of this roof that caused it to fail. Luckily roof coatings are easy to repair and maintain.

It was instal on warm winter week in Denver, CO. The daytime temperature was 45-55 degrees in late January in Denver. That is an acceptable temperature to install a coating system, but the night time temperature could can be as low as 20 degrees. The silicone and acrylic base doesn’t cure well at those low temps. In June when the heat of the summer was in full force the original roof that was coated started to expand with the high temperatures. The expansion cause the roof expand to the point of failure, as seen in the pictures.

When the roof cured at lower temperatures it was contracting. Then in the summer the roof heated up and expanded. This movement on a roof is normal and can be expected especially on metal roofs, but if the silicone cures at temperatures lower than 40-50 degrees it will likely not be able to expand in the summer heat without failing.

One of the biggest advantages to roof coatings is that they are very easy to maintain and repair. The biggest thing to keep in mind when repairing a crack like this one is that you want to make sure that the roof is completely clean and dry. With this repair we let it dry over night. Then we throughly cleaned the area we wanted to patch then we sandwiched mesh fabric between two coats of 60 wet mil of high solid silicone. The repair held up nicely and is water tight.

Silicone roof coating expansion

This silicone roof coating cured in cold temperatures and expanded to the point of failure in the heat of the summer.

This silicone roof coating cured in cold temperatures and expanded to the point of failure in the heat of the summer.

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Here is how the repair turned out.

Here is how the repair turned out.

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Here is the repair

 

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