How to prevent caravan water leaks

Caravans don’t need much maintenance as a rule. Bearings, brakes and tyres get the most maintenance attention but what many of us ignore is the one thing that’s sure to cause a lot of damage -- water leaks.

All caravans use a sealant of some type to waterproof joins, although older vans can also use an adhesive tape (often around window frames, but elsewhere too), which was a bad idea because the tape degrades quickly and the seal is soon compromised.

Thankfully caravan manufacturers have mostly abandoned this sealing method, instead using neutral-cure sealants.

Preventative measures

A caravan exposed to the weather is more likely to suffer from degraded sealant than one that is out of the elements. It’s a big call for most of us urban dwellers, to have undercover space for a van, but if you don’t have a garage or carport that you can store your van in or under, then a good quality caravan cover is the next best thing.

Caravan covers aren't perfect, set-and-forget caravan protection though. You need to take them off periodically and check that the cover itself hasn’t degraded and is allowing moisture/airborne pollutants to settle on the van. Even then, with some covers moisture can be trapped between the van and the cover. A breathable cover is the best bet.

Even then, getting a caravan cover on and off again is not exactly a fun exercise, especially for a large van. If your van has to go 'commando', then at least try to keep it clean.

Keep it clean

Washing a caravan is again a bit of an effort, but the pay-off is sealant that will last that bit longer. We’re not suggesting a weekly wash, but one every few months using a mild detergent or car wash solution will do the trick.

The roof area is the hardest but most vital bit of course,  if you’re up on a ladder with a soft-bristle broom or even a mop used carefully. Either way, with lots of water (watch for fragile items such as roof hatches)  you’ll get the job done.

Also read: How do I clean my van

Aside from wrapping the van in plastic and storing it in a dark garage, there's no way to keep body sealant like new. It’s going to degrade; it’s just a matter of when.

Danie Johanson from Complete RV Services in South Penrith, NSW reckons about 90 per cent of aluminium-clad vans he sees at his repair shop have some degree of sealant failure.

It’s pretty common for caravan sealant to let go, and when that happens it's in the lap of the gods!

If it's poor quality sealant to start with, or poorly applied, it’ll probably degrade within a couple of years, while good quality stuff could last five years or more. Unfortunately, there’s no expiry date on sealant applied to a caravan to let you know.

How to detect a leak

A water leak in the making can be a pain to find. Some are obvious, so let’s deal with those first.

Start with the caravan's (or motorhome's) roof; it's the first place a van will likely pop its sealant. Grab a stable ladder and have a look at the seams along the top sides of the van (called J-moulds), and around any roof apertures such as hatches, antennas and air-con units for any split, lifted or discoloured sealant.

Here’s where things can go awfully wrong -- if not careful, you’ll damage the roof and create leaks. If you’re not confident of doing it right, it's probably best left to an expert caravan repairer to examine and fix.

You or the repairer will need to get onto the roof of the van to closely examine the sealant around the hatches, etc for any potential breaches of the seal. However, unlike some of the latest weight-bearing composite vans, climbing on top of an aluminium-clad van roof can be a disaster if you don’t keep to the cross beams supports.

While the ladder is still out, have a look at the tops of window frames, the entry door and any vents or aerial mounts for signs of sealant degradation. Then back on the ground, check the rest of the window and door surrounds.

While the roof and windows are the most likely culprits for water ingress, you should still check the seal around 240 volt power inlet/outlets or any other component where a hole has been cut and sealed around the lower body. A water leak lower down shouldn't be as disastrous as one higher up but can still do damage if left to rot.

Lastly, look on inside walls for water stains. It may well look like the horse has already bolted, but if the stains are fresh you have a good chance of minimising the damage if you fix it quickly.

Special sealants required

We’re not going to get deep into how to fix the leak here, but if you’re doing the job yourself, don’t resort to the silicone cartridges left over from your home bathroom reno. These household silicones can be corrosive and eat into aluminium cladding.

Likewise, beware of cartridge liquid adhesives, especially if removing and resealing a J-mould or window, for instance. Otherwise if the part has to be removed later it’ll be very hard to do so without damaging it.

The right stuff for the job is neutral-cure sealant. Even though you’ll find something at a hardware chain that will do the job, try to buy the sealant from a caravan supplies shop, that should have exactly the right sealant.