How to fix a leaking caravan or motorhome roof
A wet patch on a caravan ceiling rarely sits under the actual leak. Water gets in at a joint, runs along a batten or a cable, and shows up somewhere else entirely. So the first job is finding where it's getting in, and only then deciding how to seal it.
This guide covers where caravan and motorhome roofs usually leak, how to trace the water, and how to seal the joint with tape so it stays sealed.
Where caravan and motorhome roofs usually leak
Almost every leak starts at a join or a hole cut in the bodywork. Check these first:
- Front and rear roof joints, where the roof panel meets the front or back panel. The joining strip and the sealant under it harden and crack with age.
- Awning rails, which are screwed through the side wall along their whole length. Every screw is a possible way in. (We cover these in their own guide.)
- Rooflights, vents and skylights, where the frame is bedded on sealant that shrinks and goes brittle.
- Aerial, satellite and solar panel mounts, especially ones added after the van left the factory.
- Corner caps and trim strips on the corners of the body.
Step 1: Trace the leak
Look at where the damp shows inside, then work uphill and outwards from it. Feel along ceiling edges, behind lockers and around rooflight surrounds for softness or staining. A damp meter helps you map how far the moisture has spread.
If you can't see it, get someone inside while you run a hose gently over one joint at a time, starting low and working up. Give each section a few minutes before you move on, so you know which joint let the water in.
Step 2: Decide whether tape is the right fix
Tape is a good repair when the panel and the structure behind it are sound and the problem is a failed seal at a joint, rail or frame. It's quick, it's clean and it doesn't depend on getting a sealant bead perfect.
Get the van to a workshop instead if the floor or walls feel spongy, the panel is delaminating, or damp readings are high over a large area. Rotten timber behind the skin needs cutting out, and taping over it will only hide the problem. If your van is still under a water ingress warranty, check the terms before doing any repair yourself.
Step 3: Remove the old sealant
This is the step most people skip, and it's why most DIY repairs fail. Tape bonds to the panel, not to old sealant. Cut and scrape away as much of the old mastic as you can with a plastic scraper so you don't scratch the panel.
Step 4: Clean and dry the surface
Wash the area well beyond where the tape will go. Polish and wax stop tape sticking, so make sure every trace is gone, then let everything dry completely. On plastic parts, use soapy water rather than solvents.
Step 5: Cut, apply and roll the tape
- Cut a length that overlaps the joint by at least 50mm on each side. 150mm wide tape covers most roof joints in one pass.
- Round off the corners with scissors so they're less likely to lift.
- Peel the backing and lay the tape on from the middle outwards. Don't stretch it, and don't trap air.
- Roll the whole strip firmly with a seam roller, paying most attention to the edges. Rolling is what starts the bond.
Do the job on a dry day. In cold weather, keep the roll somewhere warm until you need it, so the adhesive is soft when it goes on.
Step 6: Check it and dry the van out
Run a finger along every edge and re-roll anything that has lifted. Then get the inside dry: open lockers, ventilate the van and keep checking the damp readings. They should fall steadily over the following weeks. If they don't, the water is still getting in somewhere else.
Which tape to use
On a white van, a grey or black tape stands out. Supraseal® White Weatherproofing Tape is a 150mm butyl tape made to match caravan and motorhome bodywork. It's bitumen free, so it won't bleed black onto white panels, and it stays flexible from -30°C to +80°C as the van moves on the road. It bonds to aluminium, GRP, fibreglass and glass, and it carries our 10-year warranty. For other plastics, test a small area first.
The white tape is arriving at our warehouse shortly. Tap "Notify me" on the product page and we'll email you when it's in stock. For smaller jobs, the standard grey tape is in stock now in widths from 50mm.
Not sure which tape fits your job? Try the tape finder.