Preventing and Repairing Leaks in Your Caravan or Motorhome

Leaks in caravans and motorhomes are more than just an inconvenience—they can lead to serious structural damage, costly repairs, and a decline in your van’s long-term value. Whether you’re cruising along the Great Ocean Road or setting up camp in the Top End, water intrusion can quickly turn your dream road trip into a headache.

Australia’s diverse climate adds extra risk. From the harsh UV rays of the Outback to the heavy coastal rains of Queensland or Tasmania, RVs are constantly exposed to weather extremes. Over time, this leads to cracked sealants, warped panels, rusting frames, and even dangerous mould growth. What might start as a small drip near a skylight or window can rapidly expand into a full-blown leak affecting your ceiling, insulation, and furniture.

In this guide, we’ll explore how to spot early signs of water leaks, prevent them from happening, and fix common issues using tools, materials, and techniques well-suited for Australian conditions. Whether you’re a weekend adventurer or a full-time nomad, keeping your rig watertight is crucial for comfort, safety, and peace of mind.

Common Causes of Leaks in Caravans and Motorhomes

Understanding what causes leaks is the first step toward preventing them. Leaks rarely happen suddenly—they often result from gradual wear and tear, poor workmanship, or environmental stress. Here are the most common culprits Australian RV owners should watch for:

Ageing Seals and UV-Damaged Sealant

Over time, the original sealant used around roof joints, vents, windows, and doors begins to break down—especially in Australia’s high-UV environment. Sun exposure causes sealants to crack, shrink, or peel, allowing water to sneak through even the tiniest gaps.

Improperly Installed Accessories

DIY additions like solar panels, roof racks, antennas, or awnings are common in Aussie RV setups—but if not sealed correctly, these installations create new weak spots. Even a single screw or bracket that isn’t waterproofed can lead to hidden leaks.

Storm, Hail or Branch Damage

Low-hanging gum trees, hailstorms, and rough terrain can cause impact damage to your RV’s roof, skylights, or exterior panels. Even if cracks are invisible to the eye, water can seep in and spread through wall cavities.

Plumbing and Water System Failures

Leaks aren’t always external. Your grey water, black water, or freshwater system may have worn hose fittings, cracked valves, or loose clamps—especially in older models. Leaks under the sink or near the toilet are common entry points for moisture.

Window and Door Frame Gaps

With time and road vibrations, the seals around windows and doors can loosen. This allows wind-driven rain to creep inside, especially during storms or while driving at speed through wet conditions.

How to Inspect Your RV for Leaks Regularly

Regular inspections are the key to preventing small leaks from turning into major repairs. Ideally, you should check your caravan or motorhome for signs of moisture at least once a month—and always before and after long trips, during wet seasons, or when your RV has been in storage.

Exterior Visual Checks

Start with a thorough walk-around of your RV, focusing on the most common leak points:

• Roof seams and edges – Look for cracks, peeling sealant, or bubbling paint.

• Vents, skylights, and antenna mounts – Check that no silicone or rubber seals are lifting.

• Windows and doors – Inspect for visible gaps, dry rot, or misaligned frames.

• Boot and service hatches – These are often overlooked, but seals can deteriorate quickly.

Use a ladder to inspect the roof if it’s safe to do so, or use a drone or mirror extension for hard-to-reach places.

Interior Leak Detection

Once inside, look for:

• Soft or spongy panels in the walls or ceiling (especially near the corners)

• Staining or bubbling under the windows or around roof openings

• Discolouration or warping in cabinetry near wet areas

• Persistent damp or mouldy smell, even when well ventilated

If you feel suspicious cold patches or dampness, investigate further—it’s often a sign of hidden water.

Use a Moisture Meter and Torch

Moisture meters are affordable and extremely helpful for checking walls, ceilings, and floor cavities. Shine a strong torch at an angle across surfaces to detect warping or gloss changes—both signs of water damage.

Simulated Rain Test

To mimic rain, run a garden hose over the roof and sides of your RV in sections while someone stays inside to watch for drips or moisture. This is especially useful after resealing or installing new accessories.

Preventing Leaks: RV Leak-Proofing Best Practices

Prevention is always better than repair—especially when it comes to water damage. Taking proactive steps to weatherproof your caravan or motorhome can save you thousands in repairs, protect your gear, and keep your travels stress-free.

Reseal Seams and Joints Annually

Every year, inspect all joints, edges, and rooftop fixtures and reapply sealant as needed. Use UV-resistant, flexible sealants like:

• Sikaflex 221 (ideal for both metal and plastic)

• Bostik V60 Roof & Gutter Silicone

• Dicor Self-Leveling Lap Sealant for horizontal roof seams

Before resealing, clean the area thoroughly and remove any loose or cracked old sealant with a plastic scraper.

Apply a Roof Coating for Added Protection

If your RV roof is older or frequently exposed to sun and rain, consider applying a liquid roof coating. These create a protective, waterproof membrane that expands and contracts with temperature shifts. Great options include:

• Liquid Roof EPDM

• Henry Tropi-Cool Roof Coating

• RubberSeal Liquid Rubber Waterproofing

They also reflect heat—making your van cooler in summer.

Use an RV Cover or Park Under Shelter

When not in use, always cover your RV with a breathable, waterproof cover or park under a carport. This reduces UV and rain exposure, which are the primary causes of seal deterioration.

Check and Tighten Fixtures Regularly

Loose screws, brackets, or antennas can shift while driving, compromising seals. Tighten roof fittings, window latches, vent covers, and solar mounts every few months to avoid micro-gaps forming.

Service Water Systems Annually

Have your plumbing system professionally checked or do a DIY test each year. Focus on:

• Hose connections and clamps

• Toilet, sink, and shower fittings

• Hot water systems and grey water outlets

Use high-quality fittings like John Guest push-fit connectors or brass hose clamps for extra reliability.

How to Repair External Leaks in RVs

When a leak is found on the outside of your RV—especially on the roof or around windows—it’s important to act fast. A small drip today can lead to warped panels, mould, and internal rot tomorrow. Here’s how to repair external leaks properly and safely.

Step-by-Step Guide for Sealing Roofs, Vents, and Windows

1. Identify the Source
   Dry the area completely and inspect in daylight. Look for cracked sealant, soft spots, or small gaps around seams, vents, or fittings.

2. Clean and Prepare the Surface
   Remove all dirt, grease, and old flaky sealant using a plastic scraper and isopropyl alcohol or mild detergent. Let it fully dry.

3. Apply the New Sealant
   Use a high-quality RV sealant like Sikaflex 221, Bostik V60, or Dicor Lap Sealant. Apply evenly in a bead around the seam or joint, and smooth with a gloved finger or tool.

4. Let It Cure
   Allow at least 24–48 hours (depending on the product) to fully cure before exposing it to rain or washing.

Tip: Use self-leveling sealant on horizontal surfaces and non-sag formulas for vertical areas like walls or windows.

Temporary vs Permanent Fixes

• Temporary:
  If you’re on the road and need an emergency repair, EternaBond tape, Gorilla waterproof tape, or aluminium RV patch kits can seal a crack temporarily until you get home or to a repairer.

• Permanent:
  Always aim to remove the damaged section, clean it thoroughly, and reapply professional-grade sealant or coatings for long-term protection.

Fixing Cracked Roof Panels or Fibreglass

• For hairline cracks in fiberglass or aluminium panels:

  • Sand the area lightly

  • Clean and dry thoroughly

  • Apply fibreglass resin, a patch kit, or aluminium tape for metal roofs

In some cases, a full panel replacement may be needed—but this is rare if issues are caught early.

How to Repair Internal Water Leaks

Internal water leaks can be harder to spot—and more damaging over time. Unlike external leaks that leave visible stains, internal leaks often hide behind cabinetry, under floors, or in wall cavities. Left unchecked, they can cause rot, mould, and even electrical hazards.

Track the Leak to Its Source

Start by identifying where water is pooling or dripping. Common sources include:

• Under sinks or vanity basins

• Shower connections and taps

• Toilet inlet and flush lines

• Water heater outlets

• Behind the fridge or near concealed pipework

Use tissue paper or a moisture meter to detect dampness. Always shut off your RV’s water supply before investigating further.

Fixing Leaky Fittings and Pipes

Once the source is located:

• Tighten or replace hose clamps if fittings are loose

• Replace worn washers or O-rings in taps and connectors

• Cut out damaged hoses and insert new lengths using John Guest push-fit fittings

• For permanent joins, consider using brass compression fittings or plumber’s tape on threaded connectors

Avoid using household silicone around plumbing—it doesn’t hold up to RV movement and pressure.

Replacing Damaged Interior Panels

If the water leak has warped wood, lifted laminate, or caused mould:

• Cut out and replace damaged wall panels or floor sections

• Treat surrounding areas with anti-mould spray

• Allow everything to dry fully before closing up the area

• Use marine-grade plywood or water-resistant MDF when replacing materials

If insulation has been soaked, it should be replaced—wet insulation loses effectiveness and encourages mould growth.

Essential Tools and Products for Leak Repair

Being prepared is half the battle when it comes to leak prevention and repairs. Whether you’re a weekend camper or full-time traveller, having the right gear on board will save you time, stress, and potentially costly service fees.

Recommended Sealants (Exterior Use)

• Sikaflex 221 – Versatile polyurethane sealant for metal, wood, and plastic

• Bostik V60 – Neutral-cure silicone ideal for roof and gutter sealing

• Dicor Lap Sealant – Perfect for horizontal roof joints and self-levels easily

• Silicone Remover Gel – Helps strip old sealant safely before resealing

Always check compatibility with your RV’s construction material (fibreglass, aluminium, etc.).

Waterproof Tapes & Patches

• EternaBond Tape – Industry standard for emergency or semi-permanent roof repairs

• Gorilla Waterproof Patch & Seal Tape – Great for temporary sealing around windows or side panels

• Aluminium RV Patch Kits – For quick coverage of dings, holes, and punctures

These are excellent for on-the-road fixes until a proper sealant application can be done.

Inspection & Prep Tools

• Moisture Meter – Detects damp spots in walls, ceilings, and flooring

• Bright Torch – To illuminate hard-to-reach areas under cabinets or inside storage

• Plastic Scraper – For removing old sealant without scratching surfaces

• Nitrile Gloves – Protect hands when handling sealants or chemicals

• Isopropyl Alcohol or Methylated Spirits – Essential for cleaning surfaces before resealing

Plumbing Repair Essentials

• John Guest Push-Fit Fittings – Quick-connect options that require no tools

• Brass Hose Clamps – Durable and long-lasting compared to plastic ones

• PTFE (Plumber’s) Tape – Prevents thread leaks in water system connections

• Tubing Cutter – Handy for making clean cuts on plastic water lines

Having these tools on hand means you’re never stuck when a leak occurs mid-trip—especially in remote regions of Australia.

When to Call a Professional RV Repairer

While many RV leaks can be fixed with basic tools and sealant, some issues are too complex—or risky—to tackle on your own. Knowing when to bring in an expert can save you from turning a small leak into a major repair job.

Structural Water Damage

If you notice sagging ceilings, soft floors, or bubbling walls that extend beyond a single spot, you might be dealing with hidden rot in your RV’s framing. This often requires removing panelling, drying insulation, and even reinforcing or replacing structural elements—best left to professionals with the right tools and materials.

Leaks Around Roof-Mounted Appliances

Water intrusion around air conditioners, solar panels, or skylights may involve electrical wiring or roof cutting. Improper resealing could cause further leaks or void warranties. An RV service centre can safely reseal or replace rooftop components without damaging your van’s structure.

Persistent or Mysterious Leaks

Sometimes, no matter how thoroughly you inspect, the leak persists. This could be due to:

• Capillary action (water running along seams internally)

• Cracked sealant hidden beneath panels

• Factory faults or complex plumbing issues

A licensed technician can perform a pressure test or flood test, using specialised tools to isolate the leak path.

Insurance or Warranty Repairs

If your RV is under warranty or insured against water damage, attempting repairs yourself might invalidate your claim. Always check your coverage, and document the leak with photos before and after repairs. Let the service provider handle it if it’s a covered issue.

Conclusion: Stay Leak-Free and Road-Ready

Leaks may be one of the most common challenges faced by Aussie caravan and motorhome owners—but they’re also one of the most preventable. By staying proactive with regular inspections, using high-quality sealants and tapes, and addressing problems early, you can stop water intrusion before it does real damage.

A dry, watertight RV isn’t just about protecting the van—it’s about ensuring a safe, comfortable, and stress-free travel experience across Australia’s stunning yet rugged landscapes.

Here’s your leak-free maintenance checklist:

• Inspect seals, roof, and windows monthly

• Reseal joints and fittings every 12 months

• Apply a protective roof coating if parked outdoors

• Keep leak repair essentials onboard at all times

• Don’t ignore the signs—musty smells, soft spots, or stains

• Call in a pro when leaks are persistent, structural, or complex

By following these simple habits, you’ll extend the life of your RV, retain its value, and travel with confidence—rain, shine, or cyclone season.