Our experience is much like Cataska's. Having been enticed by many videos, and tired of white streaks following (rare) rains, we sprung for a gallon of High Traffic Zep.
We scrubbed the roof with dish soap and a deckbrush, rinsed mopped well and applied four coats of Zep. Took about a half gallon. Beautiful! Spit shine perfect!
Three years later, didn't noticed any flaking, but streaking returned and there just wasn't any Zep up there.
Started to re-Zep, but decided to try the Dicor Fiberglass coating system. My son and I applied the Dicor two weeks ago. Not any harder than the Zep, but several times more expensive. Hoping it lasts longer. We'll see.
Considered using a boat type epoxy coating from WestMarine or similar. Applied those when we owned our series of Catalina sailboats. Also hugely expensive. And not much longer life than the Zep. (No, I don't suggest Zep for boat sides.)
There are those that opine the roof is fiberglas and needs no more maintenance than a good washing periodically. Those folks and I view the world through different lenses.
Lot of blah, blah, blah there, but if SWMBO didn't yell at me like I was a red headed stepchild every time she catches me on the roof,
I would just re-Zep the roof every year or so.
Having said that, I am not adventurous enough to use Zep on our well maintained sides. (my buffer and I can reach those
).
But we did apply four coats of Zep to our wall to wall vinyl flooring. It wears like iron and looks like (clean)
glass. And, not a slippery as the un-coated no wax vinyl. We still have about a pint of our gallon of Zep.
Fair Winds and Following Seas