I consider granule surfaced BUR to be the culmination and successful integration of yesterdays material with today’s technology.
Think about it…the granules are basically miniture ballast that protect the membrane. The membrane replaces asphalt and is better undeniable. The application process (whether cold or hot) is ancient…liquid based.
It’s like 90lb on steroids + tar & gravel.
As far as I’m concerned, for smaller work, it’s the best system out there. Simple, reliable and super fast when done with an experienced crew (I, by myself, with an inexperience laborer layed 42 rolls in one day). I can’t say enough good things about it.
I remember 90lb roofs that lasted up to 40 years.
I’d be happy today to get 12 trouble free years out of an SBS Roof (but expect and see them going past 15 easily).
A properly installed granule surfaced roof will be unmovable 5 minutes after you’ve laid it (especially with cold applied adhesive). Once it stick, you have a few minutes to play with it if you have to adjust it, but once it’s set, that’s it. It’s done. I’ve found that a thin application of adhesive with good coverage is all it takes.
Honestly, I’ve seen contractors go overboard and hand seal seams with trowel grade mod bit, but that’s when it begins to curl after a few years because instead of the membrane sticking to membrane, it’s just laid in a bed of cement that gives after a while because it’s being used in an application it’s not meant to be used for. Again, a 1/4" notched trowel to leave behind just a little extra on the seams and laps (that squeezes out when stepped out) and a squeegied field has given me worry/maintenance free roofs.
But that’s just my own personal experience…other regions/application & methods might have varying degrees of success.
Granule surfaced cap sheet will last longer and require no maintenance (continual coatings after installed) and I believe provide better protection for the membrane. I think that coated smooth surfaced cap sheet (whether silver or white) might be better at reflecting u.v. rays and possibly heat, but the studies are all over the place for the past 15 years that I’ve been keeping an eye on it.