# Flat Roof/Torch Down Finishes



## AaronB (Jan 29, 2005)

This is right up my alley.

Snow roof, like mosst other acrylics, in my opinion, are not suited as a waterproofing membrane. This is what the 2-3 gallons per square is designed for. Knowing the chemical makeup of roof coatings, and their limitations, is key to choosing the right coating for your particular need.

Heres the skinny...

Reflective coatings lengthen the life expectancy of many roofing systems by simply reflecting the UV. As a reflective coating, I have put these acrylics down at one gallon per square, and it reflects. Without a UV inhibitor, the UV rays will literally cook the oils out of the modified asphalt (bitumen), causing your roof to "dry", crack, curl, disbond, and ultimately fail. All smooth modified bitumen has to be coated. Granulated does not need a coating, as is has the ceramic granule surface to reflect the UV, just like a shingle.

If youre looking for an inexpensive reflective coating, aluminum roof coating has been used for years with great success. The only problem is you will need to re-coat it every 3 years or so.

Be sure to let your roof cure 90 days before applying any reflective coatings.
If one is looking for a waterproofing coating, polyurea is the way to go.


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## MikeinBurien (Nov 12, 2005)

Hi Aaron,

Thanks for the info. Good stuff. I did some searching around for the polyurea, but there's so much information I couldn't see any specific to roofing on bitumen. Are you aware of a specific product that I can do some research on? I'm sure it's probably the more expensive route, but I should at least take a look.

The aluminum roof roating is probably the more practical material, but recoating every 3 years doesn't sound all the pleasant - although it should be pretty straight forward. 

I'm wondering how the uphill neighbors will react to it. 

Also, a local roofing guy mentioned a product called "carmac". I'm sure I'm getting the spelling wrong, but that's what it sounded like he was saying. Are you aware of product with a similar name? If so, what is it and is it appropriate for the bitumen roof?

The 90 day cure is good advice as well. After that, are there typically any temperature requirements for the coatings? In 90 days it will be February and in the NW temps are still above freezing, probably 38-42 at night. 

Mike


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## AaronB (Jan 29, 2005)

karnak is a brand name widely recognized in the roofing industry.

Polyurea is a maze of information that must be sorted out. We usually use the polyurea coatings for waterproofing;lining systems. They are a bit costly for a reflective coating. \\

If you wait until spring to coat your roof, it should be just fine. I would say go to home depot and look for their elastromeric acrylic roof coating in white for the best reflectance and long term use. Be sure to pressure wash your roof without damaging it before applying the coating.


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