Most RV roof leaks start in the sealant around a vent, an edge, a corner molding or a seam, not in the middle of the membrane, and the stain inside is rarely under the hole. Find the source first, then patch it with the material your roof maker approves for that membrane.
RV Roof Repair: Finding the Leak, Patching It, and When to Re-Roof
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At a glance
- Look here first: sealant around roof fixtures, edges, corner moldings, seams and the slide-out box, because Keystone says a leak there may not show up inside where you can see it.
- Patch with what your membrane maker approves: rubber, plastic and fiberglass roofs each take different cleaners and patches, and one tape will not bond to all of them.
- Stop and call a shop: a roof your builder does not call walkable, or any roof still under a membrane warranty.
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Where is the leak coming from?
Water gets in where a sealed joint has opened, and the stain inside can sit well away from it. Keystone warns that a leak at a corner molding may not show inside at all, so damage can build before you see anything. Check the joints in this order:
- Roof fixtures: the air conditioner, roof vents, skylight, antenna and solar mounts, and the sealant bead around each flange.
- The roof edges and the front and rear corner moldings.
- Seams in the membrane and any earlier patch.
- Wall attachments: compartment doors, refrigerator and furnace vents, lights, awning feet, water fills and the water heater.
- The slide-out, which has its own roof, end walls and moldings to inspect and reseal. Worn slide-out seals can let water in while the room is extended.
Tip: Measure the ceiling stain's position from the nearest wall and transfer it to the roof. Treat that spot as a starting point and check every sealed joint around it.
Leaks that look like roof leaks
A wet ceiling near a window or door may not be the roof at all. Winnebago says windows and doors are prone to leaks, especially in extreme weather. Keystone says to check around them inside after rain and to vacuum the window weep holes clear so water can drain.
Do not seal the two deliberate gaps Winnebago leaves in the sealant on the bottom flanges of windows and doors. They let water drain out, and sealing them traps it inside the wall. A leaking frame is window resealing or replacement work, not roof work.
Is your roof walkable?
Check your own manual before you climb, because builders do not agree. Keystone says units with factory installed ladders have walkable roofs, and some without a ladder do too. Jayco and Grand Design say the decking lets you walk the roof with caution. Grand Design suggests moving on hands and feet to spread the weight, and limits the roof ladder to 300 lbs.
Forest River says a factory installed rack or ladder means a reinforced roof, while an aftermarket one likely means none. If your manual does not say your roof can be walked on, stay off it and have an RV shop do the inspection and the repair. Makers also warn that the membrane is slippery when wet.
Check the warranty before you buy anything. Alpha Systems voids its warranty for any roof work done before you have written authorization, and Dicor requires pre-approval of DiFlex II warranty claims before repairs. Dicor's Patchit kit is not for roofs with a manufacturer's warranty. Jayco does not cover water damage from failing to maintain or reseal.
What to patch with, by roof type
Match the cleaner and the patch to your membrane. One patch can cover several roof types, but coatings, primers and cleaners do not cross over.
| Roof | Clean with | Patch with |
|---|---|---|
| EPDM rubber | Dicor Rubber Roof Cleaner; no petroleum distillates, harsh abrasives or citric cleaners | Dicor EPDM Rubber Roof Repair Membrane, Dicor Patchit kit, or an Alpha rubber patch set with P1671 splice adhesive |
| TPO | A TPO-safe, non-abrasive cleaner (Winnebago); Alpha uses a household granulated cleaner such as Spic-n-Span | Dicor Patchit, Dicor DiSeal TPO tape, or an Alpha SuperFlex patch applied by adhesive or heat weld |
| Metal, aluminum or galvanized | The cleaner the tape maker names | EternaBond tape, or Dicor Patchit |
| Fiberglass | Dicor Fiberglass Clean & Prep, which is not for EPDM or TPO | Forest River's stopgap only: cover the break with plastic and tape the edges, then have it repaired |
Sources: Dicor's Patchit kit page, Alpha Systems' patch instructions, EternaBond's RV page and Winnebago's owner's manual. Keystone says a punctured or cut TPO roof can usually be patched with dealer kits, and a whole new membrane is seldom necessary. Resealing the joints afterward is a separate job: see RV roof sealants by roof type.
Tip: Cleaner advice conflicts, so follow the maker of your patch. EternaBond rules out detergent type cleaners and lists EternaClean, lacquer thinner or acetone, while Alpha says to scrub with a household cleaner. On old TPO, PVC or Hypalon, EternaBond says to score the surface with sandpaper first.
Patching a tear or puncture
You can patch a hole yourself if the roof around it is sound and the hole does not run into a vent, air conditioner, skylight or other rooftop penetration. These are Dicor's Patchit kit steps.
- Check that the patch will extend 2 inches beyond the hole in every direction. Use one patch per repair, never over a previous repair or coating, and trim any loose roofing.
- Lay the patch down, center it and mark the edges with chalk or pencil.
- Clean at least 2 inches beyond the marks with hot water, mild detergent and a stiff bristle brush, then rinse and dry. Confirm the cleaning method with your roof maker (see the table).
- Peel the backing and position the patch using your marks. It cannot be repositioned once it touches the roof.
- Remove the top liner and press the patch down with a roller or the heel of your hand, from the center toward the edges.
- Run a 5/16 inch bead of lap sealant around the entire edge of the patch and smooth it. Do not use the sealant as cement under the patch.
- Leave the patch two hours before moving the RV.
Tape has its own temperature limits. Dicor's DiSeal TPO tape goes on between 32°F (0°C) and 110°F (43°C). EternaBond tape goes on between 40°F (4°C) and 150°F (65°C), with EternaPrime below that.
Tip: Below 60°F, Dicor says to keep the patch and sealant at room temperature until you need them, and never to warm them with an open flame or extreme heat. The lap sealant is a flammable liquid whose vapor can flash.
When patching is not enough
Some roof marks are harmless; widespread failure is not. Dicor says air bubbles in an EPDM roof are normal, come and go with the weather and should not be punctured. Alpha says black streaks along the decking seams are mildew and do not compromise the membrane.
A patch will not fix a membrane that has failed over a wide area or shows the signs Dicor links to petroleum distillate damage: swelling, uneven thickness and loose areas. Alpha says its roof coating is not a patch, and a leaking roof should go to a service center for evaluation.
On a re-roof, Dicor says the decking must be replaced too, because the adhesive needs a porous substrate to bond. That decking carries your weight and your air conditioner: have an RV technician do it.
Common questions
How do I find where my RV roof is leaking?
Work outward from the stain through every sealed joint, in the order listed above. Keystone asks for corner moldings and wall attachments to be checked every six months, so a joint that looked fine last season is still worth checking.
Can you fix an RV roof leak with tape?
Yes, on many roofs. EternaBond lists its tape for EPDM, TPO, Hypalon, aluminum, galvanized steel, wood and fiberglass. It will not stick to silicone-treated surfaces or to a surface that was not cleaned and prepped properly.
Can I walk on my RV roof?
Only if your builder says that model can be walked on. Even then, Keystone says a walkable roof is designed for one person doing routine maintenance, not for chairs, coolers or several people.
When does an RV roof need replacing instead of patching?
Rarely after a single puncture. Dicor says a properly applied patch should last the life of the membrane if you check it periodically, and that a well maintained roof should last a minimum of 20 years.