How to Check A Motorhome or Caravan for Damp

Looking Out For, Preventing and Repairing Dampness

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:

Section 1

Why do Motorhomes and Caravans Get Damp?

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:

  • Condensation from cooking, showers, wet clothes — and even breathing.
  • Water ingress — sometimes rain can enter in through gaps near the windows, awning rails, doors and roof lights.

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.

Section 2

Fighting Damp with a Damp Meter

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.

How to Use a Damp Meter

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.

Damp Meter Results and What They Mean

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:

0 - 15% - Indicate a dry surface, with no damp.

15 - 20% - Could be the start of a damp problem. Make a note and keep an eye on it.

20 - 25% - A potential damp problem. Consider calling a professional or investigating further.

25 - 30% - You very likely have a water ingress problem. Remedial work may be required. But it might not require stripping down, unless there are more serious signs - such as damp pimpling, staining, or a softness in the area.

Above 30% - Serious damp problem. A complete strip down may be required. Requires urgent attention.

A word of advice about budget moisture meters

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.

Humidity Meters

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.

Section 3

How to Check for Damp in your Motorhome or Caravan

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:

  • Check around the seals and sealant around the windows, seals, doors — and anywhere where you might have drilled bits of equipment (such as aerial points and bike racks) or accessories onto the main body.
  • Check all sealant for signs of damage. Such as cracks, knocks, any peeling. If it’s rained heavily recently, it might make it easier to spot any water entry points.
  • On the inside, check your cushions, curtains and fabrics for any musty smells.
  • Run your hands over the wall boards to make sure there’s no pimpling (or ‘dimpling’ as some people call it). And also to make sure the walls don’t feel wet or spongy to touch.
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“Pimping” on the board is a sign of dampness.

  • Look for signs of discolouration on the walls, such as black spots or marks. Damp can also sometimes cause staining on the walls of a blue or even pinkish colour. This discolouration or staining tends to occur near the windows and lockers, so be sure to check there.
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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.

  • If the floor feels spongy to walk on, or even creaky, this could be a sign of either water ingress or damp.
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This is a good example of an Elddis that has leaked across the lower rails and has stained blue.

  • Water can sometimes hitchhike on channels and pipes as it enters your vehicle. This can ‘dump’ water in what looks like a random part of your motorhome or caravan. In such instances, it can be hard to tell where the point of entry is. So keep this in mind when checking for ingress.
  • Inspect internal screws for signs of rust.
  • If you’re buying a used motorhome or caravan, look out for signs it’s had dampness issues in the past. If some of the internal panels have been replaced, that could be an indication.

Where You Should Test for Damp

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:

  • Peel up the rubber on the windows and test behind it.
  • Seats and inside the bed lockers.
  • Inside the cupboards.
  • Standard ingress points (windows, doors, and any places where the seams run — such as where the roof meets the ceiling).
  • Around any point where you have fitted your own accessories (as water can get in via drill holes). This can include cycle racks, awnings, and so on.

Section 4

Getting Rid of Mould and Mildew

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.

A word of advice about cleaning mould and mildew

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.

Health Risks Associated with Damp, Mould and Mildew

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:

  • Allergic reactions to the mould spores.
  • Asthma and breathing problems.
  • An increased chance of infection in immunocompromised people.
  • Mood swings, memory loss, fatigue — and even migraines.
  • Skin problems, such as rashes, eczema, hives and so on. 

Section 5

Tips for Reducing the Risk of Damp, Mould & Mildew in your Caravan

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:

Clean and vacuum the interior often, making sure to wipe down all the surfaces with anti-bacterial wipes or with a disinfectant spray.

Air your motorhome or caravan regularly. Even if you’ve got it locked away for the winter, remember to visit from time to time and let some fresh air circulate. If possible, remove the cushions and mattresses. Especially if you’re leaving it idle for a long period.

Give the interior a good clean before you set off for the new season, even if you gave it a thorough clean at the end of the last season. This will get rid of anything that might have settled while your vehicle was in storage.

Regularly perform damp checks with a moisture meter.

Regularly check for any signs of water ingress. Make sure to check around windows, doors, anywhere where there are possible entry-routes into the main body of your motorhome or caravan.

Wipe away condensation from the windows and doors as soon as possible.

If any of your soft fabrics or furnishings get too wet — to the point where you don’t think they will dry well — consider getting rid of them.

If you’ve stored away your fabrics or furnishings for a period of time, give them a good checking over before using them again.

Use a dehumidifier, or dehumidifying crystals (or other moisture control products) to keep any areas in the interior where air doesn’t circulate that much under control.

Have your motorhome resealed on a regular basis. This will help to avoid leaks and condensation. If it isn’t included already, you can ask for a technician to look into this during your annual habitation check. This is well worth doing, so I’d definitely encourage you to pay a bit extra for it — if you have to.

Have your roof joints resealed at least once every three years. This is to err on the side of caution, as it will help to prevent damage to the side panel joints.

If your motorhome or caravan is bumped or scratched, try to get it repaired as soon as possible. Knocks can break the exterior surface, allowing for potential water ingress points.

Try not to use a jet washer when cleaning the exterior. Or if you do, be very careful. The force from the jet could damage seals on the outside, and you could be forcing water ingress in yourself!

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. 

Reducing Condensation and Increasing Ventilation

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. 

Tackling Water Ingress and Leaks

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. 

Protecting your Motorhome or Caravan in Storage

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. 

Section 6

Damp Myth Busting

There are three common myths when it comes to damp that I would like to debunk.

  • “There’s no dampness. You’d be able to smell it!” WRONG! Very rarely can you smell damp. You’ll need a damp tester (moisture meter) to find out.

  • “My motorhome is wood free, doesn’t get damp and doesn’t need servicing”WRONG! Motorhome models such as Bailey with their Alutech chassis, Hymers with their PUAL Construction and so on, still have floors made of wood. So, if the seals in the walls and sealing fail, the water will run down and get into the floor. Before you even realise something is wrong, you will end up with a spongy damp floor.

  • You can see damp” — SOMETIMES! Sometimes the walls will discolour, sometimes they will pimple and sometimes the aluminium rots from the outside in severe cases. But a lot of the time, by the time you see it, a lot of damage has already been done. That’s why it’s important to keep on top of, and prevent dampness in the first place. 

Section 7

Frequently Asked Questions (FAQs)

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.

Give me a call if you need help with a damp problem.

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.

Thinking of selling a motorhome or caravan with damp? Need a damp check to know how much it’s worth? Then we can help.

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.

And because we operate within a large network of buyers, we’re able to offer great value prices to our customers. Just check out our five-star Trustpilot reviews

We’ll come and collect your motorhome or caravan personally from a location of your choice, and pay for it INSTANTLY via an instant bank transfer. 

There are no call-out fees or hidden charges. And unlike private Internet listings, you won’t have to pay for advert listings or worry about dodgy buyers, time-wasters, or inconvenient viewing times. 

All you have to do is tell us about your vehicle on our respective motorhome and caravan pages, fill in a few details, and we’ll get back to you ASAP. 

Either way, I hope you found the information in this article useful. Thank you for reading. 

A Note from the Author — Shane Malpass

In the last 10 years, we’ve helped hundreds of happy customers to sell up their caravans quickly, without a fuss and no matter what the condition — for a great price in return.

So if you want to simply sell your caravan and move on, or are looking to upgrade to a newer model or motorhome — we’re here to make you happy and keep you satisfied. Your opinions matter to us. Just check out our five-star TrustPilot reviews!

You can give me a call directly on 07879 816463. In the meantime, find out more about me here and follow our YouTube channel for all the latest caravan and motorhome reviews, tips, and tricks.

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