warning on roofing cement product

rtoni

I picked up a can of Bakor / Henry #810-47 Ultimate Roofing Repair. I see a warning on the can that says not to use the product over coal tar pitch roofing. I have used other products in the past (Black Knight, or Roof Proof) before - I just assumed anything related to DIY foor repair would be asphalt product. Just curious - is there any product sold in any box store that would qualify as a coal tar product? I'm guessing coal tar is something only used on flat roofs, e.g. commercial jobs?

shazapple

Coal tar and asphalt are not the same thing. What kind of roof are you repairing and what is its age?

Maintenance 6

Coal tar is still used on flat roofs, but not as often as it once was. Many flat roof products are asphalt based. Asphalt is made from oil and is lighter than water. Coal tar is is made from a coal derivative and is heavier than water. The only thing they have in comon is that both are black. Otherwise they are not compatible. When somebody decided that coal tar was carcinogenic, many companies drifted away from it, although it is an excellent roof product. A roofing supply house can probably fix you up with some repair products, but I doubt you'll find it in a box store.

rtoni

thanks for the replies. My roof is just asphalt shingle and relatively new (under 5 years). I think I have no issues with this product based on the explanation given, but when I read any product instructions and see "warnings" I like to understand what they mean. Box store folks generally not much help in that regard. I appreciate the reponses - thanks again...