Motorhome water damage can lead to costly repairs, disrupt your travel plans and decrease the value of your investment. It’s perhaps the most preventable wear and tear on a recreational vehicle. All it takes is scheduling regular checks and maintenance.
In this blog, we delve into how motorhome water damage occurs and the areas of your motorhome that are most prone to it. We also discuss how you can prevent water damage — including the all-important annual motorhome water tightness test.
Learn to spot early trouble signs and keep your motorhome cosy and dry — and unhealthy mould and mildew at bay.
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Why it’s important to prevent water damage
Unchecked water intrusion can wreak havoc on your motorhome — corroding metal and delaminating materials. This weakening of structural components not only compromises the safety of your vehicle but also significantly reduces its lifespan.
Prevention is far more cost-effective than dealing with the aftermath of a leak. Stopping water damage from occurring in the first place is crucial for:
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Retaining the structural integrity of your motorhome
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Keeping healthy — water ingress can give rise to mould and mildew which creates health risks
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Staying safe — water damage can cause electrical issues which can create fire hazards
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Feeling comfortable — dampness, musty odours and damaged furniture make for an unpleasant travel environment
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Maintaining value — by preventing leaks you’ll protect your investment and its potential resale worth
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Avoiding expensive repairs — to address mould and replace damaged materials.
Most motorhome manufacturers have invested heavily in reducing the risk of water damage by using tried-and-tested materials and construction methods. They put their reputation on the line by offering a water tightness or body integrity warranty. These warranties vary in length from five to ten years, depending on how confident the manufacturer is about their motorhomes.
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Warranty periods for the major motorhome brands in New Zealand
*From information available online at the time of writing in July 2024. All warranties are subject to the manufacturers’ terms and conditions. |
You can take proactive measures to prevent water damage and the hassles it brings. But first, it’s important to know how water ingress can happen.
Find out how to prepare for a winter road trip where rain and inclement weather is likely — then download our winter road trip checklist to help you get ready.
How water damage occurs
Motorhomes are more vulnerable to water pooling on the roof as they have flatter rooftops than houses and minimal guttering. As a result, they’re more susceptible to water ingress over time.
The habitation unit structure also endures vibrations and bumps when your motorhome is mobile, which can cause water leakage, both:
- Internally around the plumbing, and
- Externally with degraded window and skylight seals.
Adding these factors together, you have a perfect storm for water penetrating your motorhome.
A stronger motorhome helps prevent water damage
Most motorhome habitation units have a frame which is clad with glass reinforced plastic (GRP) and alloy. The key benefits of using these materials include being strong, lightweight, durable and resistant to corrosion.
The roof, floor and end panels of motorhomes are often strengthened with a thermoplastic polymer like ABS plastic. This material is resistant to UV radiation and moisture — so it doesn’t easily degrade or corrode when exposed to the elements.
Joins, edges and transitions between different materials require sealant, fixing screws and alloy strip and bead coverings for protection.
The increased use of high-tech adhesive bonding and interlocking joins in modern motorhomes has greatly reduced their susceptibility to water ingress. This has allowed some brands, like Bürstner, to confidently offer a ten year warranty on water tightness.
However, water ingress can still occur due to sealant cracking or fasteners failing. Early detection is the key. That’s why RV manufacturers usually require an annual water tightness check from an approved agent as a condition of the warranty.
Motorhome areas prone to water leaks
Just as important as your annual water tightness test are your own regular checks of potential problem areas. While no motorhome is entirely leakproof, certain areas are more likely to experience water damage. Discover where these common trouble spots are, and you can be proactive in preventing minor leaks from becoming major headaches.
The motorhome roof
The roof of your recreational vehicle takes a battering from the weather gods — making it one of the most common places where leaks originate. It’s important to regularly:
- Inspect the sealant — around vents, skylights, air conditioners and other openings
- Look for cracks, peeling or missing sealant
- Pay attention to the corners and edges of your motorhome’s roof — where seals can often fail.
Motorhome roofs are the preferred mounting point for kayak and surfboard racks, skylights and solar panels. But poorly installed aftermarket additions to your motorhome roof can create vulnerable points where water may seep in.
If you intend to add exterior accessories to your motorhome that won’t be fitted by the manufacturer, first check how they may affect your water tightness warranty.
Consult the terms and conditions of your water tightness warranty — and consider advice from a professional installer of motorhome accessories. If your warranty terms permit additions like solar panels on the roof, you’ll want those modifications completed correctly by an expert technician.
However, the integrity of your recreational vehicle’s watertight seal is essential — and the safest approach is to purchase a motorhome with factory-fitted rooftop accessories.
Rooftop air conditioners
If your motorhome has a rooftop air conditioner, problems can occur if the exterior outlet becomes blocked by accumulated dust. Air conditioners are designed to remove moisture from inside your motorhome, by collecting water droplets in a drain pan before escaping through a drain tube.
A dust or debris blockage can cause the water collection to back up inside the drain pan, eventually overflowing. If this happens, water can seep into the interior of your motorhome — potentially damaging the walls, ceiling and electrical systems.
Meanwhile, stagnant water in the air conditioner’s drain pan can become a breeding ground for mould and mildew — leading to an unhealthy habitation space.
Learn about releasing moisture, preventing mould and other benefits of ventilation.
Window and entry door seals
Window and entry door seals play a vital role in maintaining the water tightness of your motorhome. These seals can become pathways for water intrusion if they’re:
- Damaged or worn out
- Improperly installed.
Driving through heavy rain is an ideal scenario for water to sneak past these seals and find its way inside. Water can seep through gaps, cracks or deteriorated sealant around the edges of your motorhome’s windows and doors — resulting in dampness, mould growth and even structural damage.
Check for moisture buildup or discolouration around your window and door frames. If you notice any drafts, it could also indicate a compromised seal.
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Inspect, inspect, inspect Regular inspections and maintenance of your window and entry door seals are crucial for preventing leaks. Look closely for gaps or signs of wear and cracking. Replace or repair seals as soon as you find faults — to ensure you maintain a secure and watertight RV. |
Wall-to-floor joins
Constant movement and vibrations while driving puts stress on your motorhome’s joins and seals — eventually leading to cracks and gaps. A combination of complex construction and exposure to various weather conditions, like rain and humidity, can degrade sealant over time.
Modern motorhome manufacturers apply improved construction techniques which ensure wall-to-floor joins rarely present problems anymore. However, if you own an older motorhome, it’s important to routinely check these joins.
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Any wetness on your motorhome’s floor or carpet is usually the result of road spray water seeping through the join — between the bottom inside edge of the wall and the floor. Paul Owen — Award-winning motoring journalist |
Internal plumbing
Most motorhome owners focus on external sources of water leaks. However, it's just as important to address internal risks — like within your motorhome's plumbing network.
RV plumbing networks are connected by threaded and compression fittings that may loosen over time. The pipes, hoses and fittings that channel water through your vehicle also experience wear and tear, vibrations and pressure fluctuations — which can lead to structural damage if left undetected.
When conducting water tightness inspections, also check your motorhome’s awning attachments and external storage compartments. If seals are worn out or damaged, these locations may be vulnerable to leaks.
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Tips when checking for water damage
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The annual water tightness test is your best defence
Regular and thorough checks of your motorhome will help to detect problems early but another step is required in order to maintain your motorhome’s water tightness warranty.
Protection, peace of mind and potential savings make the annual water tightness check an absolute must under warranty — and a smart investment beyond that.
The benefits for you and your RV over the long term are substantial. You’ll maintain a safe and comfy living environment, keep your motorhome warranty valid and save money on more extensive repairs.
The test is your best defence against water damage to your motorhome because it will:
- Pinpoint the origin of leaks in their early stages — even if they’re not yet noticeable
- Prevent expensive repairs — which may involve replacing damaged components
- Protect your investment — by helping maintain the condition of your recreational vehicle and its value
- Keep your warranty valid — if water damage does occur, you’ll be covered as long as your motorhome has had its water tightness test each year
- Provide peace of mind — you’ll be able to relax and enjoy road touring without worrying about possible leaks.
You don’t want to let water ingress progress to a point where it’s visually detectable on your motorhome’s internal walls. The result may be a major and costly repair job to restore the structural integrity of your motorhome.
Not sure how much an annual motorhome water tightness test will cost? Use our cost of ownership calculator to work out what the test will cost as well as get an indicative cost of owning a motorhome in New Zealand.
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Even if an annual water ingress check isn’t a requirement of your motorhome’s warranty, it’s worth getting one done regularly. Keep to a schedule of yearly checks so you can identify problems before any mould begins to eat away at your motorhome’s body structure. Paul Owen |
What the water tightness check involves
A certified water tightness technician equipped with a highly-sensitive digital moisture monitor will take readings all over your motorhome — including inside the cupboards, compartments and cubbyholes. This expert will:
- Locate any conduits for your motorhome’s plumbing
- Examine the window, vent, and door seals thoroughly
- Inspect the roof closely
- Check the body joins and sealant.
When dampness is recorded, the cause of the water ingress will be tracked — so that the problem can be fully diagnosed.
See our list of water tightness agents to find one near you.
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The accuracy of the water tightness check is dependent on the quality of the moisture meter and the experience of the person operating it. Professional testers will use meters to identify dampness in panels located underneath ceramic tiles and behind bathroom fittings — such as toilets and shower cubicles. Buying a cheap moisture meter online and using it yourself may ultimately prove to be a false economy. Paul Owen |
How to prevent motorhome water ingress
No matter how frequent and extensive your water tightness checks are, prevention will always be better than cure. Water ingress can cause extensive damage to your motorhome's structure and interior but taking a few proactive steps can significantly reduce your motorhome’s risk of water damage.
Store your motorhome under a protective shelter
The more shelter from the weather your motorhome has, the better. You have a few options at different price points that will all do the job:
- Add a motorhome port to your house — if the garage isn’t large enough to accommodate your motorhome
- Buy a canvas-style RV shelter — which can be put in place and anchored down where you want it
- Get a motorhome cover — either standard size or custom-made
- Store your motorhome offsite in a secure facility during the times when you don’t plan to use it.
Weatherproof your motorhome
A plethora of RV weatherproofing products are available on the market. From join sealing tape to rubber sealant to final sealant topcoats — you can really go to town on the cabin exterior to reinforce its water tightness.
Do-it-yourself weatherproofing may not be for you, but if it is, these types of products will prove useful. Allow one to two days to complete the full weatherproofing process, which involves applying:
- A cleaning product — over the motorhome exterior
- Sealing tape — to all joins, and skylight and window seals
- Liquid rubber waterproof sealant — at a minimum final thickness of one litre of sealant for every square metre over the exterior of your motorhome.
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Two or three coats should achieve this minimum final thickness. Leave the sealant to dry for at least 12 hours before applying the final rubber topcoat — at a rate of four litres per 25 square metres of exterior surface area. Paul Owen |
Manage condensation
Cooking, taking showers, drying wet clothing or towels inside and boiling the kettle all create steam and the potential for condensation to build up and linger inside your motorhome. Condensation can lead to mould and mildew, similar to water ingress. You can minimise this issue by:
- Making sure to open window and roof vents when cooking, boiling the kettle or drying textiles indoors
- Cooking outside when the weather’s good
- Opening the bathroom roof vent when taking a shower
- Boiling water in the kettle while the kitchen ventilation is operating.
Other solutions for managing condensation include placing an insulated external windscreen cover over your cab window and good ventilation.
Read our blog about monitoring your motorhome on the road — which highlights how to check for damp spots.
What to do if you detect water damage
Any signs of water damage need to be looked at immediately, as waiting can considerably worsen the problem. Take these steps to address the issue:
- Identify where the water is coming from — closely inspect the usual problem areas like doors, windows, vents, seals and plumbing fixtures.
- Contain the water leak — which may involve towels to absorb it, a container to catch it or temporarily sealing the spot with waterproof tape.
- Dry the damp area thoroughly — and promote airflow by opening vents and windows, or using a fan or hair dryer if you have one. If carpets or soft furnishings are affected, remove them from the motorhome and dry them outside.
- Record the extent of the damage — taking photos or video to support warranty and insurance claims.
- Consult with an expert water-tightness technician — to assess and repair the damage.
If your motorhome is still under warranty for water tightness, contact the dealer to initiate a claim.
Keeping your RV watertight is a non-negotiable. The benefits of maintaining your motorhome’s structural integrity and value, avoiding repairs, plus staying safe, healthy and comfortable are paramount.
Learn more about motorhome warranties.
