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How to Spot and Prevent Damp in Your Motorhome – 8 Simple Steps & Tips

It’s the one big thing motorhome owners dread – the smell and sight of damp!

Even with manufacturing techniques advancing all the time there is always a chance that faulty seals around windows, doors and roof lights can let water seep in. In older vehicles, awning rails together with body panels and corner joints can be a big source of damp problems.

Be aware that as you drive your motorhome around there can be a lot of natural flexing and movement in the panels and joints. This is why flexible sealant is used. Over time some cheaper sealant types can become brittle, detached or just break, especially if a cheap, low-quality sealant is used during manufacture or, more usually, home/amateur repair.

Left alone, water ingress and damp can quickly cause a lot of damage to your motorhome. But act quickly and the problem can be easily, and usually inexpensively, sorted.

How to recognise damp in your motorhome?

Thankfully, you shouldn’t find any damp in any of Oaktree’s motorhomes as we thoroughly test them. If anything in your motorhome is not to our high standard we will always repair it prior to the vehicle going on sale. After all, we give you a 3 year RAC warranty with the vehicle so we want you to have total peace of mind.

But if you’re buying a used motorhome privately, look out for any unusual looking alterations, such as different interior wall boarding, as it can point to a past damp issue.

What are the first signs of damp?

Trust your nose! A musty smell is usually the first sign of damp. Other things to look for are:

Obvious Signs Of Damp

  • Check for signs of black spots around windows, doors and roof lights. You may also spot some blue or pinkish staining to the walls.
  • Look out for soft or spongy surfaces. If you can press your finger into the walls and it leaves a dent then you may well have a serious damp problem underneath.
  • A creaky floor, or a spongy feel underfoot, is often a sign of delamination – where the layers of plywood flooring have become separated due to moisture ingress. It can be very expensive to repair if you don’t catch it in time.

Get moisture meter

Buying a good quality damp or moisture meter is always a good investment and can give you an early heads up before the problem spreads. It is useful to test in specific areas of your vehicle at least every six months and certainly before and after it goes into storage.

Here’s a typical moisture meter used by caravan and motorhome professionals but these can cost over £170. There are cheaper options available, but being able to check out your vehicle to a high degree of accuracy, and consistency, is a good investment that can alert you to a growing problem and potentially save many thousands of pounds in repairs.

Protimeter Digital Mini – NEW


How to prevent damp in your motorhome?

Prevention is always better than cure so here are some tips on preventing damp in your motorhome.

Let the air flow

From experience, good ventilation is key. One of the simplest and most effective ways to avoid damp is by using your motorhome as often as you can throughout the year. If that’s not practical, then on a monthly basis, open the doors and windows for an hour or so to let some fresh air in. If you find a build-up of condensation on windows and walls, then simply give them a good wipe down to dry them.

When leaving your van for long periods open all cupboard doors and adjust all cushions and mattresses to give a good circulation of air around them.

Use Extractor Fans When Showering and Cooking

Both showering and cooking generate a huge amount of water vapour into the confined space of your motorhome; you’ll probably to wipe off the mirror in the bathroom after you’re finished in the shower and don’t forget to wipe down the walls too. Your kitchen windows get fogged up when you’ve got something bubbling away on the stove. Switching on the extractor fans will draw the air heavy with water vapour out of your motorhome and leave it on for a little while after you’ve finished up.

Check for leaks

As well as an annual habitation check or service, you should always be checking for any damage to seals. And if you do spot a leak after washing the motorhome or a heavy downpour, don’t ignore it. A quick repair could save you lots of expense in the longer term.

Be constantly on the look-out for any signs of damp, particularly at the end of the season. Make sure you check under the beds, the backs of cupboards and lockers and even under the beds.

When you store your motorhome for the winter it’s best to use a waterproof but breathable cover. This will help prevent water ingress along with those regular checks and door-opening visits.

Curb the condensation

Try not to dry clothes inside your van. sometimes it’s unavoidable but try to dry wet clothes in an awning to prevent condensation. However careful you might be, condensation tends to be slowly drawn into the woodwork and it is then difficult to dry out.

Motorhome Extractor FanWhen cooking on the stove top, turn the gas/electric down to the lightest of simmers and use lids on saucepans. Turn on any extractor fans and open the windows slightly to let any steam escape.

When showering, keep the bathroom window slightly open, and the door closed to avoid steam getting into the rest of the motorhome. Wipe the walls down when you’re done.

Dehumidifier crystals, bowls of salt or even cat litter in a tray can help to soak up excess moisture in the air to reduce damp.

Treating damp and mould

Remove patches of mould and mildew with a mould removal spray. Once dried use a mixture of clove oil and water and spray the area, leaving it for 20 minutes before wiping dry.

If you can’t treat mould yourself or it has spread too far then it’s best to call for some expert help.

Once any timber framework is affected by damp it can be tricky to sort out. Ideally, the wood needs to be thoroughly dried out and then the bodywork re-sealed. It can take time and you need to make sure you thoroughly dry out your caravan or motorhome using heaters and/or dehumidifiers. It’s probably the time to call in the professionals too. An approved repairer or workshop will be able to carry out a full inspection and will be well equipped to tackle the problem.

Take care when storing your motorhome for winter

We’ve written a comprehensive guide to motorhome winterisation and recently recorded some video too. Have a look at these and follow any advice given.

Where should I test for damp with my moisture meter?

Here are some suggestions where to check for damp in your motorhome

  • Peel up the window rubber and test the wall underneath
  • Test inside any under-bed lockers and under seats especially on or near the outside walls
  • Test inside cupboards especially towards any joints or corners (Damp may not show in the centre of a panel)
  • Check around normal ingress points such as around windows or doors. Look for any points where seams and joints run and where corners meet. Such as where the walls meet the roof, ceiling or floor.
  • Check around any non-standard accessories such as cycle racks, roller awnings, satellite systems etc. In fact, check anywhere where a hole has been drilled into the outside skin of the vehicle.

Please Note: All wood contains moisture and according to the time of year and amount or type of use the moisture content will vary. You will never get 0% but as you can see from the table below 0%-15% is quite normal.

Damp meter readings fall into the following categories:

  • 0-15% – no cause for concern
  • 15-20% – professional investigation required
  • 21-30% – remedial action possibly required. Motorhome may show signs of damp or water ingress
  • Over 30% – severe structural damage may be occurring

In summary

Don’t forget that proper motorhome maintenance is essential if you want to enjoy your vehicle as long as possible. Preventing damp ingress is always the best course of action, but if you do find tell-tale signs then act quickly. If caught early, solving a damp problem need not be expensive. That said, it is always worrying that you caught and fixed the source of it.

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