Caravan World — 10 July 2012

MOST CARAVAN LEAKS occur at a join or attachment hole where a screw or rivet holds down the sheeting to the frame. Some leaks can be hard to track to their source, but one I recently found was a pretty straightforward job. Check out the step-by-step for evidence.

The leak was coming through at the rear left corner wall of the pop-top, and water was leaking through at a fair rate. The first job was to raise the roof so we could see if there was any sealant missing on the join around the roof and its base. Everything seemed okay, so we decided the easiest thing to do was remove the side moulding to inspect for leaks.

The first thing to remove on this type of moulding is the decorative centre strip, which peels out to reveal the attachment screws. Removing these screws showed the first hint of trouble underneath – the shanks were badly corroded and some snapped off at the heads. We weren’t certain this was the source of the trouble but, so far, it was looking like the main culprit.

Once we had removed the screws holding the side moulding, it was then a matter of carefully peeling away the moulding. Using a scraper to gently pry it away from the body helped because the aluminium is easy to bend out of shape.

With the moulding off the bare join, exposing the timber frame, it was obvious plenty of water had made its way into the area. The timber was wet along the seam, but seemed firm when poked with a screwdriver, a good sign it hadn’t rotted. Looking closely at the moulding, it was clear from tracking marks that water was getting in via one of the screw holes.

We took off the awning bracket and rear marker light to find evidence of water ingress through screw holes. These would later be sealed with the silicone sealant.

The timber needed time to dry out (which can be hastened with a blow-dryer). This particular van had fibreglass side panels, which would’ve been very time-consuming to remove. But with an aluminium skin you’d likely be tempted to pull the cladding away from the top join to have a closer look for timber rot. We show a different van getting a moulding re-fitted in the below images, but the principle remains the same.

We made sure the moulding and its attachment point on the van were scrupulously cleaned with methylated spirits. It was then a matter of applying a thick bead of silicone sealant down each side of the edge where the moulding goes. It’s important to note the silicone has to be the good stuff – without the acidic properties you find in roof and gutter sealant – otherwise you do more harm than good.

This sealant lasts an hour before going off and you have to allow time for clean-up, so we made sure we had everything close to hand. We placed the moulding onto the back of the van and started screwing it into place. With all screws in we attacked the clean-up, first coating the area with a liberal spray of soapy water. We then began lifting off the excess sealant with a plastic scraper (ours was actually a custom Perspex job). Don’t use a metal scraper here because you’ll find it hard not to mark the paint.

With the bulk of the excess scraped off, we gave the area another soapy spray and got a paintbrush with cut-down bristles (to make them stiffer, which works into the sealant better), dipped in in turpentine and scrubbed at the remaining excess.

With a few wipes as we went, the area came up nicely. The sealant continued to bulge out for a further 24-hours, so the next day we grabbed our scraper and took it along the dry bulging bits. With the moulding insert back in, the job was done.


1 It’s clear the leak had been coming through the cupboard for a while.

2 Side moulding must be removed in order to find the source of leak.

3 Carefully peel away the moulding.

4 Corroded screws suggest a leak.

5 Water tracking marks reveal the source of the leak.

6 Awning attachment plate shows more water marks around screw points.

7 Rear light wire holes may be leaking at screw points and must be re-sealed.

8 A check shows this frame seems to have avoided wood rot.

9 Apply thick bead of sealant to both sides of the corner.

10 Fit the moulding onto edge.

11 Allowing sealant to ooze out both sides ensures a good seal.

12 Spray moulding area with soapy water to help the clean-up.

13 A plastic scraper lifts excess without scratching the painted surface.

14 Use a paint brush dipped in methylated spirits to loosen any excess.

15 Wipe away remaining excess sealant.

16 Sealant will bulge for 24 hours, so remove any final excess the following day.

Source: Caravan World Apr 2012

More tech articles


tech talk leak caravan fix mend how to tutorial tech repairs maintenance

External Links