Leaking caravan awning rail: reseal it or tape it?
The awning rail runs along the side of your caravan or motorhome, screwed through the wall every few inches. Each screw is a hole in the bodywork, sealed only by the mastic behind the rail. When that mastic dries out, water runs down the rail, finds a screw hole and soaks into the wall.
Signs your awning rail is leaking
- Damp or staining inside, just below ceiling height along the awning side.
- Soft or bubbling wall covering near the top of that wall.
- High damp meter readings along the line of the rail.
- Dried, cracked or missing sealant where the rail meets the wall, or rust streaks from the screws.
Rails often leak at the ends and corners first, where the rail turns or is joined. Check those carefully.
Option 1: Remove and reseal the rail
This is the traditional repair. You remove the rail, cut through the old mastic behind it, clean everything back, and refit the rail on fresh sealant or mastic strip.
Pros: it renews the seal at its source, behind the rail.
Cons: it's a long job, often a full day or more on a big van. Old rails are easy to bend while you're removing them, and screws can snap. If you're going down this route:
- Use stainless steel screws when refitting. Plain steel and brass can corrode against an aluminium rail and skin.
- Support the rail along its length as you take it off, so it doesn't kink.
- Clean every trace of the old mastic off the rail and the wall before you reseal.
Option 2: Tape over the rail
A wide butyl tape laid along the top edge of the rail, onto the wall above, stops water ever reaching the screw holes. It's much quicker and doesn't risk damaging the rail.
Pros: an hour or two instead of a day, no rail removal, and a continuous seal along the whole length.
Cons: it covers the top of the rail, so check it won't stop your awning sliding in. It also doesn't dry out water that's already in the wall.
How to tape an awning rail
- Scrape any old sealant from the top edge of the rail and the wall just above it.
- Wash the area, removing all polish and wax, and let it dry completely.
- Lay the tape so it bridges the joint between the top of the rail and the wall, with at least 50mm on the wall. Keep the awning channel clear.
- Work in manageable lengths, overlapping joins by at least 50mm, and press it on from the middle outwards without stretching it.
- Roll it firmly with a seam roller, especially along both edges.
Which should you choose?
If the wall behind the rail is sound and damp readings are low, taping is a fast, durable fix. If the wall is already wet or soft, the rail needs to come off anyway so the wall can be dried and repaired. Tape over a wet wall will just seal the water in.
If your van is under a water ingress warranty, check with your dealer or service centre before you do any repair yourself.
Which tape to use
Supraseal® White Weatherproofing Tape is 150mm wide and white to match the bodywork. It's bitumen free, so it won't stain, and it stays flexible from -30°C to +80°C as the van flexes on the road. It's paintable if you need to colour-match, and it comes with a 10-year warranty. For more on finding leaks, read how to fix a leaking caravan or motorhome roof.
The white tape is due into stock soon. If you need to seal the rail now, our grey Supraseal® tape is the same bitumen-free butyl tape, in stock for next-day delivery. 100mm suits most awning rails, and it can be painted over to match the van.