Resealing an RV Roof | Motor Sportsland Blog

Laying fresh sealant over a dirty roof

Resealing an RV Roof usually fails for a boring reason: the surface wasn't clean when the new sealant went down. Utah sun and dry air bake a chalky film onto roof membranes all summer, and sealant that lands on that film sticks to the dust instead of the roof. It looks fine in the driveway. Three months later the edges lift.

Wash the whole roof first with a cleaner meant for your roof type, rinse it well, and let it dry. Then go back over every seam you plan to seal and wipe it down again. Dicor Self Leveling Lap Sealant is the standard for flat, horizontal seams around vents and skylights, and it flows out smooth once it's on clean material. It comes in black and in tan, so you can match what's already up there.

Caulking on top of old, cracked sealant

Piling new sealant over a cracked bead is the most common shortcut, and it's the one that hides problems. Water gets under the old layer through a split you buried, travels along the seam, and finds a screw hole. You won't see it until there's a stain on the ceiling or a soft spot in a corner.

Old sealant that's still bonded flat and uncracked can usually stay. Anything loose, peeling, chalky or split needs to come off with a plastic scraper so you're not gouging the membrane. Take your time around screw heads. Once the bad material is gone and the seam is clean and dry, lay a fresh bead and let it flow into the joint instead of sitting on top of a crusty ridge.

Using self-leveling sealant on a vertical surface

Self-leveling sealant does exactly what the name says. Put it on the flat roof deck and it settles into a neat, even bead. Put it on a front cap, a side wall, the vertical face of an AC shroud or a rooftop antenna base, and gravity pulls it down into a sagging mess that's thin where you needed it thickest.

Vertical and sloped spots call for a non-sag product. Dicor Non-Leveling/Non-Sag Lap Sealant stays where you tool it, which is what you want on anything that isn't level. It's available in black and in tan to match the rest of your roof work. Keep both kinds in the bay if your coach has a lot of transitions, because switching products mid-job is easier than fighting a runny bead.

Treating a split or a gap like a caulk-only repair

A hairline crack in a bead is a caulk job. A separated seam, a gap at a corner, or a spot where the sealant has pulled away in a long strip is a different problem, and dumping tube after tube into it rarely holds. The sealant bridges the gap for a while, then the joint moves on the highway and it tears again in the same place.

That's where a sealing tape earns its keep. The Dicor Self Adhesive Patch For Epdm, Metal And Fiberglass (DiSeal Sealing Tape, 4 x 50' white roll) gives you a continuous surface over the seam instead of a bead stretched across a void. Clean and dry the area, press the tape down firmly so there are no air pockets, and work out the wrinkles as you go. You can still run sealant at the edges afterward.

Call the service department if you find a soft spot underfoot, a sagging ceiling panel, or delamination near a roof edge, because that's structure and it isn't a sealant repair.

Call us too if the roof around a vent fan, an antenna or an AC unit needs the unit pulled, since anything wired or gas-related should be handled by a technician.

If you aren't certain your roof is safe to walk on, let us put it on a lift and inspect it instead of guessing.

Resealing an RV Roof in the middle of a hot afternoon

A roof in Millcreek in July gets hot enough to skin sealant over before you've tooled it, and the membrane itself expands in the heat. Seal a seam at its widest, then watch it contract overnight, and you've built stress into a brand new bead. Early morning is better. A shaded corner of the lot is better still.

Geocel — 10-Oz Sealant Clear — 10-oz sealant clear

Dry air works against you too, because it pulls moisture out of the bead fast on top while the inside is still curing. Give it the full cure time before you call the job done and before you park it under sprinklers. Geocel ProFlexRV Flexible Sealant Clear is worth knowing about here. It's a flexible sealant that bonds to virtually all RV materials, withstands joint movement and temperature change from travel, stays elastic, is paintable, and adheres to damp surfaces.

Guessing at which product your roof takes

Roof membranes aren't all the same, and neither are the sealants. Owners come in with a tube they grabbed somewhere, use it on the wrong surface, and end up scraping it all back off a season later. Color is part of it as well. Tan sealant on a white roof with black beads looks like a patch job forever.

Bring us your year, make and model, or snap a photo of your roof and the existing seams. Our parts counter in Millcreek and in Spanish Fork will match the right sealant, the right color, and the right tape for what's actually on your coach. We'd rather spend five minutes on that than have you redo the work.

How often this needs doing

Most owners inspect the roof two or three times a year and touch up anything cracked as they find it, with a fuller reseal every few years depending on how much sun the rig sees. Stored outside in Utah, the sealant ages faster than the membrane under it. Check the front and rear caps, every vent, the skylight, the AC gasket area and anywhere a screw passes through. Write down what you find so you know what moved since last spring.

Frequently asked questions

How do I know whether I need self-leveling or non-sag sealant?

Go by the surface, not the location. Flat, horizontal seams take self-leveling; anything vertical or sloped takes non-sag, and plenty of roofs need both.

Can I use sealing tape instead of sealant everywhere?

Tape is for covering a seam, a split or a gap with a continuous surface, and it works well for that. Most owners use it alongside sealant rather than in place of it.

Can I reseal if the roof is still a little damp?

It depends on the product. Geocel ProFlexRV Flexible Sealant Clear is described as adhering to damp surfaces, but most sealants want a clean, dry seam, so check what you're holding before you start.

What if I find water inside after I reseal?

Stop and call our service department. Water that's already inside usually means it traveled from somewhere other than the spot you sealed, and tracing it takes more than another tube of lap sealant.

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Order now: call our parts counter at 801-262-2922, or stop in at either store, Millcreek in Salt Lake City or Spanish Fork. Browse all our RV parts and accessories.