Damp is the curse that all motorhome and caravan owners fear. In many cases, it can cause extensive (and very expensive) damage before we even notice there’s a problem. So it’s important to know how to spot, prevent, and treat dampness before it’s too late.
That’s what this guide is for. So let’s jump right in:
Dampness is what happens when moist air gets trapped in a small or confined space. Because motorhomes and caravans are confined living spaces by nature, they are the perfect trap for moist air.
And because the UK and Ireland are rainy countries with wet climates, there is always plenty of moist air that can easily get trapped inside.
Here are the most common sources of moist air that can lead to dampness:
Older motorhomes and caravans are more likely to suffer from severe damp, especially models that have wooden frames. And while many of the newer models have designs intended to prevent water ingress, they are not immune and water may still get inside.
Damp testing a motorhome or caravan should be done — at the very least — once a year. And if you get an annual habitation service (as you should) then a motorhome or caravan damp test is normally carried out as a part of that service. But I would recommend doing a damp meter test every month. Or at a stretch, once every three months.
Regular damp checks are important because seals can break down over time (and especially if they weren’t sealed properly in the first place) as you’re travelling about. And if water gets even the slightest chance to sneak in through the cracks it will take it.
Water ingress is so common and destructive that it’s the first thing I look for whenever I buy a motorhome or caravan off of a customer. The cost of materials to replace wood isn’t expensive. It’s the labour that is expensive. Replacing the walls, roof or floor will most likely mean stripping the units, fixtures and fittings out in the affected area before then taking the walls apart — potentially taking hundreds of hours in labour.
So it’s definitely important to regularly damp check your motorhome or caravan.
A damp meter looks a bit like a walkie-talkie. They measure moisture levels as a percentage. You can do this by holding the prongs on top of the damp meter against areas where you think there could be damp.
There are lots of different types of damp meter available to buy on the market. Including budget types and more expensive, professional models. I use the Protimeter SurveyMaster as it is one of the most accurate model-types on the market. It has a bit of a heavy price tag (approximately £400). But it’ll last a long time and could save you a lot of money in repairs if you keep on top of things.
A typical damp or moisture meter uses prongs to detect dampness. The more damp an area is, the more electricity passes between the prongs — giving a moisture reading as a percentage on the meter.
Here’s what the different caravan damp readings mean, and what action (if any) you’ll need to take:
You can buy really cheap moisture meters, such as the Extech MO55 for about £40. Budget meters are all likely ‘consumer-grade but they might not always be super accurate. And the results they give can be impacted by the weather outside. So if you get a result between 15-20% on a budget damp test, try not to panic too much. Just make a note of the area and the weather conditions and try again on a dry day.
And if you pick up what seems like a serious damp problem, I would also recommend getting the area tested again with professional help. A professional technician will be able to accurately see if there is a serious problem or not, before you start ripping things out and spending a fortune on repairs.
Some people also use humidity meters to monitor the amount of moisture inside their motorhomes or caravans. Similar to moisture meters, a humidity meter will give a percentage reading as to how much water it detects in the air.
If you have a humidity meter and the reading is 50% or more, then you should do some investigative work to see if there’s any water ingress or damp. Obviously a humidity meter won’t tell you where the ingress is coming from — you’ll need a moisture meter for that — but it’ll serve as a warning.
Remember that other factors may give a false reading on the humidity meter. Such as if you’re cooking, or have had a shower recently.
Try to get into the habit of checking for damp whenever you clean or do any other regular job with your motorhome or caravan.
Here’s what you should do:
“Pimping” on the board is a sign of dampness.
This motorhome is extremely damp. The wall is physically coming away from the kitchen units, plus as you can see the wall has changed texture, shape and has gone soft.
This is a good example of an Elddis that has leaked across the lower rails and has stained blue.
If you have a damp tester (a moisture meter), you should use it wherever you suspect there could be damp! But if you’re just doing a routine check, make sure to test the following areas:
What do you do if a caravan has damp? Well, if you catch the problem early, then you may be able to stop it without the need for professional help. You can do this by giving it a good clean.
Because mould and mildew can make people feel unwell, it’s best to wear gloves, goggles or even a face mask before attempting to remove it. Especially if you suffer from allergies or asthma.
To clean away mould and mildew, fill a bucket with warm water and a good amount of detergent. (Do NOT use bleach to clean up. Use either washing up liquid, or a mixture of vinegar and warm water.) Then wipe away at the black spots with a scrubbing brush. You can loosen up stubborn mould with mould removal spray, and finish it off by scrubbing at it hard with an old toothbrush.
To prevent the mould from coming back, at least temporarily, fill a spray bottle with a tablespoon of clove oil and warm water, and apply it to the areas where you’ve just scrubbed away the mould. Leave it to settle for 20 minutes, before wiping the solution away and drying the area.
If your bedding, cushions or fabrics are mouldy, either consider getting rid of them or washing them on the highest setting possible for their fabric type. (And afterwards, make sure they are bone dry before putting them back.)
Then I’d recommend giving the whole interior a good wipe down and vacuuming, to get rid of any lingering mould spores.
Finally, wipe any of the wet surfaces dry, and open the windows to let your motorhome or caravan air for an hour or so to finish the job.
No one likes cleaning up mould and mildew. Which is why it’s important to monitor for dampness and water ingress in the first place.
Aside from looking unsightly and damaging your interior living space, mould and mildew can cause quite serious health problems. And especially in children, the elderly, and pretty much anyone with an underlying health condition.
Some of the health problems include:
Of course, the trick is to stop mould and mildew from appearing in the first place. If you want to know how to fix damp in a caravan or motorhome and prevent it from becoming a problem, you’ll have to keep on top of things.
Here’s my motorhome damp check sheet list recommendations:
There’s a whole jet washer debate in the motorhome/caravan community. Visit our tips and advice page on how to clean your motorhome for more useful information about jet washers and general cleaning practices.
A big part of preventing dampness is by reducing condensation and increasing ventilation. And for that reason, it gets its own section.
To encourage air circulation around the motorhome, you’ll need to get into the habit of keeping the windows open a crack — or by switching on extractor fans during cooking and even showering.
Try not to dry any wet clothes in the motorhome. If you can, try to keep them under an awning or (even better) let them dry in the sunshine if possible. That goes for you too! If you, your children or the dog are wet, try to dry off appropriately with a towel before going inside.
Humans can contribute to the condensation problem just by breathing. This becomes most problematic when we are asleep, as we essentially stay in one place blowing out moist air for hours at a time.
Obviously you can’t stop breathing. So if you can, try to have the windows open on their security latches, and make sure any of your vehicle’s ventilation points aren’t blocked off or covered up. Ideally, you’ll vents both high and low in your living space, to better aid the circulation of fresh air.
The strategic placement of dehumidifier crystals, salt, and even cat litter, can’t hurt. Although not everyone is convinced they work all that well. Personally, I have an electric dehumidifier that works wonders, so if the problem’s really serious, you can alway try one of them.
You can clean up as much as you like, but if you don’t stop the water ingress from happening in the first place, the mould will just come back.
And while water ingress mostly comes from the outside, sometimes it can enter through cracks in your shower, pipes, sinks and taps. The good news is, in any of these cases, the fix is fairly easy and affordable.
If the water is coming from outside however, then it gets more difficult to treat. But a good place to start is by replacing the sealant around the windows, the roof lights and other areas. If you’re confident the ingress is coming through broken sealant and you’re planning for a bit of DIY, make sure to choose a quality, flexible sealant. One that’s recommended for motorhomes and caravans.
Other types of water ingress are harder to sort out on your own, and may require professional help. Especially if it’s not obvious where the damp has got in, and if the timber framework and floors are saturated. In these cases, you will need to address the problem urgently and the wood will almost certainly need to be dried out or replaced, and the bodywork resealed.
Many people put their vehicles in storage at the end of late autumn and don’t return to them until the start of the new season in the springtime. But if you aren’t careful, you could come back again after the winter period to find mould growing everywhere.
Now, it’s generally a good idea to check up on your motorhome or caravan in storage on a regular basis anyway, to make sure everything is OK. As a water problem can soon become catastrophic if you aren’t around to give it immediate attention. The same is true to prevent damp issues and mould.
If you’re putting the vehicle into storage, give it a deep clean beforehand. Take all the necessary precautions: check for leaks, cracks, and any signs of deterioration in the rubber or sealant. Keep the windows open throughout the cleaning process, and make sure all the surfaces are dry when you’re done.
Then either remove or position your fabrics, cushions, curtains and bedding in the middle of the living space. So that air can breathe around them. Leave the cupboard doors open as well.
After you’ve done all that, inspect the storage area itself to make sure no water is getting in there. If you’re using a cover, make sure the cover is breathable and itself waterproof.
I’d recommend giving your vehicle a check once a month or so. And while you’re there, open the windows and let the air circulate for a good hour each time.
Simple checks like this will make sure your motorhome or caravan is ready to go as soon as the new season starts up again — and will help to prevent very expensive and destructive accidents from happening.
If you’d like more information on how to store your vehicle properly, check out our guide on how to prepare your motorhome for winter storage. It comes complete with a handy checklist, visuals, and other further tips and advice.
There are three common myths when it comes to damp that I would like to debunk.
A damp meter reading of under 15% is good. Such a low reading generally means there is no moisture in the air. But if the readings are over 15% — even if only by a little bit — you might want to investigate further. Readings of 15-20% could be a sign there is a problem.
The Protimeter SurveyMaster. In my opinion, this trusty damp meter is the one you really should be using and the one that most professionals use. It will cost you about £400, but you’ll easily get 10 years of use out of it. And it’s a small price to pay if it means keeping on top of damp and stopping it from developing into an expensive repair problem down the line.
If you’re budgeting, the Extech MO55 is a lot cheaper (about £35-40) and will also help you to detect dampness. But it may not be as reliable as the Protimeter SurveyMaster.
Yes. Damp can lead to the growth of mould and mildew, which can give off spores. These spores can trigger allergies, asthma and lung problems. In more serious instances, these spores can weaken immune systems, and the toxins they carry can even affect brain function. Some people have reported chronic fatigue, memory loss, migraines and skin rashes from the “toxic air” that mould and mildew can create in damp enclosed spaces.
Yes. If you fix a damp problem, then heat should dry it out naturally over time. You can even speed up to process with gentle heat from a fan heater on a low setting, or by keeping it well ventilated.
But letting damp dry out could take time and do further damage to your caravan or motorhome. If you think significant damage has already been done, you might want to consider getting it checked.
Move all your cushions, rugs, and other fabrics away from the exterior walls. Then take the curtains and nettings from the windows down. Preferably, you should remove them from the caravan or motorhome altogether in order to prevent dampness from settling in. And although this should work, you should still regularly check your motorhome throughout the winter months to make sure there isn’t a damp problem.
Visit our How to Winterise Your Motorhome guide for more tips on how to protect it during the colder months.
On average, a tradesperson will charge about £50-75 an hour on a damp repair job. There are lots of things that can influence how big or small the price is for a damp job. If the damage caused by the dampness is extensive, it will take a lot longer for an experienced tradesperson to fix it. It isn’t uncommon for a major damp issue to cost £1000s to fix.
I hope by now you realise why it’s important to check for dampness. The next thing you should do is keep a log of what happens next. For starters on how to fix caravan damp wall damage, try drawing out both sides, the back panel, roof and floor, and write down the numbers the damp meter is showing to keep an eye on its percentage readings.
If you catch a damp issue early, often it’s just a case of resealing the affected area. If you do have any questions, please give us a call on 01283 240237, or you can call my personal number on 07879 816463. We’re always happy to help and advise as much as we can.
If you’re worried about expensive damp repairs and want to sell your motorhome or caravan, we’ll buy it from you quickly and hassle-free.
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Either way, I hope you found the information in this article useful. Thank you for reading.
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