RV Roof Leak Repair

What causes RV roof leaks?

Most RV roof leaks start at a penetration (anything that passes through the roof) or a seam, not in the middle of the membrane. Sealant ages, gaskets compress, and Ontario freeze-thaw pries every crack wider. The usual suspects:

• Skylights and roof vents
• Air conditioner gaskets and surrounds
• Seams, edges, and end caps
• Slide-out roofs and toppers
• Ladders, racks, antennas, and accessories
• Cracked, lifted, or layered-over lap sealant

Signs the leak may be worse than it looks

A small stain can sit at the end of a long water path. Soft spots, sagging ceiling panels, a musty cabinet, or stained walls mean water has been inside a while.

Is it the air conditioner or the roof?

Water under the A/C after rain has three possible causes. A failed A/C gasket, the seal under the unit, lets rain in and shows up at the ceiling grille. A plugged condensate drain drips on hot, humid days with no rain at all. A roof leak near the unit stains the ceiling panel around it, not just the grille. We check all three before anyone touches sealant. Caulking around the A/C shroud fixes none of them.

How do you find an RV roof leak?

We start on the roof: sealant, seams, penetrations, the membrane, and old repairs. Inside, we look for stains, soft spots, and odour, and take moisture readings to see how far the water travelled. If the entry point is still unclear, we hose-test one area at a time. Then we fix the entry: old sealant out, damage repaired, fresh reseal. Products are matched to your roof: EPDM rubber, TPO, fiberglass (fibreglass), or aluminum.

How do you test an RV roof for water leaks?

Three ways, in order. First we look: the sealant at every penetration, the seams, and any old repairs, with a photo of each. Then we measure: a moisture meter across the ceiling, walls, and floor shows how far the water has travelled past the stain. If the entry point still isn’t clear, we hose-test one area at a time, from the bottom of the roof up, while someone watches inside. That order matters. A hose run over the whole roof at once tells you it leaks, which you knew, and not where. A leak test isn’t a separate booking: it’s the first part of every leak repair visit, at your driveway, seasonal site, or storage lot, and you get the photos and the meter readings either way.

What can I do before the technician arrives?

Keep the water out without making the repair harder. A few things that help, and two that don’t:

• Tarp or cover the area if you can do it safely from a ladder
• Photograph the stain, the roof above it, and nearby penetrations, and note the date
• Pencil around the stain so you can see if it grows
• A clean, dry seam can take roof repair tape (EternaBond-style) as a stopgap
• Don’t spray Flex Seal or smear silicone on it. Both contaminate the membrane, and the repair has to remove them first
• Don’t layer new lap sealant over cracked old sealant. The new bead inherits every crack

What if the leak has already caused water damage?

If we find soft sheathing (the plywood deck under the membrane) or damage inside, we photograph it. Then we walk you through the options, from a targeted repair to structural work. Sealing over damaged structure isn’t a repair, and we’ll say so.

How much does RV roof leak repair cost in Ontario?

There’s no flat rate, and a price given before anyone sees the roof is a guess. Final pricing depends on roof size, roof condition, prep requirements, travel, access, visible damage, and hidden damage found during inspection. So we start from photos or an inspection.

You see the full estimate before any work begins. Nothing gets done that you haven’t approved, and the number doesn’t change without your say-so.

Reviewed by Paul B., RV roof technician, on October 18, 2026.