The System

The RV aftermarket is full of brush- and roll-applied roof products. They are cheap, they are easy, and on a unit that lives outdoors and moves at highway speed they are a two-to-four year answer.

The gap is not marketing. It is physics. A roll-applied acrylic is roughly half water or solvent by volume, so a 20-mil wet film dries to about 10 mils — and it thins further at every edge, flange, and radius, which is exactly where you needed the build. It also cures by evaporation, which means hours of open time during which dew, dust, or a passing shower can compromise the film.

Alasta Seal is 100% solids and reacts rather than dries. The two components mix at the gun and gel on the surface in three to six seconds. Wet mils equal dry mils. Vertical and overhead surfaces take full thickness without sag. And the unit is tack-free before the applicator has finished walking to the other end of the roof.

For an operator, that last property is the one with dollars attached. Cure time is bay time.

Wash with Super Orange Cleaner. Twice on any unit that has not been properly cleaned. Then flood-test a section with water: if it sheets evenly the surface is clean, if it beads anywhere that spot still has wax or plasticizer on it and the membrane will release there first.

Remove failed sealant, do not overcoat it. Every cracked, chalky, or lifting bead around vents, fans, AC shrouds, and cap seams comes off to bare flange. New material bonding to old caulk is not a bond.

7001 Primer, doubled at details. One pass across the field, a second on every flange, seam, and termination. On an RV the substrate changes several times across one roof — membrane, aluminum flange, fiberglass cap, painted gelcoat — and 7001 is what makes the finished membrane continuous across all of it.

Then spray. Details first, field second, terminations wrapped over the drip rail last.

EPDM. Most common on towables. Sheds a chalky plasticizer layer with age that must be fully removed — two cleaning passes minimum on a neglected roof.

TPO. Cleans easier but is slicker. Priming is mandatory, not a judgment call.

Fiberglass one-piece roofs and caps. Common on higher-end coaches and fifth wheels. Scuff any remaining gloss, then clean and prime. Mold-release wax is the failure mode here.

Aluminum. Degrease, scuff the oxide, prime. Detail rivet lines heavier — dissimilar-metal corrosion is common under the fastener heads.

Previously coated. Adhesion-test with a putty knife at an edge. Soundly bonded coatings can be cleaned, scuffed, and primed over. Anything that lifts in sheets has to come off entirely.