my camper roof is a sheet of aluminum over plywood, the Alsan is neither rubber or metal, but an extremely hi-performance 2 part PMMA resin.
it's properties are beyond me, i'm not a chemist, but i know it DOES work, and works well.
some info on PMMA roof coatings
http://rci-online.org/wp-content/upl...11-goodrum.pdf
easy to mix up (just like bondo), easy to apply-brush or roller app only, hardens but stays flexible, is good to go after about 15 mins drying time, can be applied to just about any kind of surface, is practically indestructible once fully cured-impervious to chemicals, oil, gas, can be applied practically anywhere (even vertically and upside down)
foot traffic, and even vehicle traffic does not affect or hurt it.
down side, it's not cheap....but nothing good ever is...it only cost me some time, we have Alsans at our shop, but i prob used about $50-70 bucks worth of it if i had to go buy it...speaking of, you will most likely never find this stuff at your local hardware or builder store. usually it will have to come from a dedicated roofing supplier
we did a "floating" roof over a poop tank at the sewage plant couple yrs ago. we put down a 2-ply torch-on membrane, then spent $35 000 (ya, that's not a typo..) coating it with 2 layers of Alsans.
the Alsans was put over the torch-on to protect it when the floating roof gets all the "clinkers" (poop particles) pressure washed off the roof....without the Alsans, the pressure washers would strip the torch-on membrane like nothing in no time. according to the engineers, the roof should have at least a 30-40 yr life span with constant pressure washings
my camper roof is for all practical purposes, "done for life"
this stuff is great for rv roofs where there is lots of protrusions thru the roof (screws, vents, roof racks, skylites, AC units, fridge vents, etc, etc.....) nothing out there that is better or easier to seal these protrusions than Alsans.
a 25 lb pail, i used about 1/4 of it to do two heavy coats- i figure about 6-8 lbs or so up on my roof
