Simple DIY Stone Proofing Caravan Grey water lagging.

Stone Proofing Your Caravan’s Grey Water Pipes: A Simple DIY Upgrade.

Cruising down Australia’s rugged backroads in a caravan can be the adventure of a lifetime – until a flying stone shatters a pipe and brings your trip to a messy halt.

Many outback and regional roads have deteriorated to such a point where loose gravel and broken bitumen are now commonplace. When your caravan’s wheels, or a passing vehicle’s tyre, kick up stones, they become high-speed projectiles. Exposed underbody components, like grey water plumbing, are sitting ducks for these projectiles.

Simple DIY Stone Proofing Caravan Grey water lagging.

Clean and inspect the PVC pipes before covering the pipes with lagging.

Grey water pipes on caravans are typically made of PVC plastic due to its low production cost and ease of installation. Unfortunately, PVC is known to be relatively brittle, especially after years of exposure to heat, cold, and road vibrations.

Our trusty Essential Caravan just celebrated its eighth birthday. I was concerned that the aging PVC pipes might be becoming brittle and vulnerable to a stone strike that could crack or shatter them. Once a grey water outlet pipe is ruptured, you’ll start leaking waste water all over the road or campsite – not only a messy inconvenience but also an environmental no-no in many places.

Prevent Undercarriage Damage

It’s not just theory or paranoia. Seasoned travellers have countless tales of undercarriage damage. Even at sensible speeds, a flung rock can break plumbing lines, and PVC drain pipes are often the first to suffer, especially on rough roads. Sadly, standard touring caravans, like our ‘On-Road’ Essential Caravans, generally lack dedicated underbody stone guards or shielding. Off-road models, on the other hand, typically come with some undercarriage protection.

Fortunately, protecting these vulnerable pipes doesn’t require an expensive workshop visit or any heavy engineering. Foam pipe lagging, the kind used for insulating hot water pipes or air-conditioning lines, doubles as excellent padding against impacts. It’s cheap, lightweight, and easy to install. As a bonus, it also provides some thermal insulation, but our primary aim here is physical protection.

Fire Rated Insulation 42mm x 13mm Wall x 2 meters. Product #1904355 from Actrol – Reece.

Why foam lagging?

It’s a method even the pros recommend. According to many caravan and RV repair experts, you can use either corrugated flexible conduit or a foam sleeve to guard plumbing lines. However, plumbing lagging is convenient because it often comes pre-slit and in a neutral colour (unlike pool noodles, which are bright neon). The foam sleeve completely wraps the pipe, shielding it from direct hits by rocks or debris. If a stone does hit, the foam disperses the force, usually leaving the pipe underneath unscathed. Additionally, the lagging protects the pipes from other hazards, such as flying road spray, sticks, or even the odd stray piece of tyre rubber – anything the road throws at them.

For our project, we sourced 2-meter lengths of 42 mm (inner diameter) pipe insulation with a 13 mm thick foam wall – importantly, but not mandatory a fire-rated type of foam for added safety. (This was purchased from Actrol, part of Reece’s plumbing supplies, at around $20 for a length – a small price to protect expensive plumbing.) The 42 mm size foam was a perfect fit over our caravan’s grey water pipes, and the 13 mm wall provides a good cushion against stones. Fire-rated closed-cell foam is durable and won’t easily shred or soak up water and dirt. In essence, we’re giving our PVC pipes a cushy “soft armour” that absorbs and deflects impacts.

Once the pipes are cleaned, inspect for leaks.

DIY Installation: Step-by-Step in an Afternoon

One of the best aspects of this upgrade is that it’s simple and quick – it only took an afternoon to completely wrap the foam around our caravan pipes. Here’s a breakdown of how to install pipe lagging around your grey water pipes:

Thoroughly Clean and Inspect:

Begin by washing the underside of the caravan, paying particular attention to the area around the grey water pipes. Remove built-up mud, grit, and dust. This not only makes installation easier (nobody enjoys dirt falling in their face while working under a van!) but also lets you inspect the pipes for any existing damage or leaks. It’s crucial to fix any leaks before lagging, since you don’t want to hide a problem. Fortunately, our cleaning revealed no cracks – a good sign for a 7-year-old van.
Measure and Cut the Lagging:

Cut your foam insulation tubes to the required lengths for each section of pipe. Most lagging comes in straight one or two-metre lengths, so you’ll likely need to cut some pieces shorter for various segments. We had to split our foam down the centre; however, some products come with a lengthwise slit already. If not, like me, you’ll need to slit the lagging down the centre yourself using a sharp knife. By splitting it lengthwise, you can easily open the foam and wrap it around the already installed pipes without needing to disconnect any pipes.
Wrap the Foam Lagging Around the Pipes:

Open the slit and push the foam lagging around the pipe, encasing it completely. Ensure the foam covers all exposed areas of the PVC pipe. Especially any sections that hang low or near the wheels, where stones are most likely to hit. In tight spots or T-junctions, you can notch the foam or trim little pieces out so it doesn’t kink – this helps it wrap around corners snugly.
Secure with Cable Ties:

Close the foam around the pipe and secure it in place with cable ties (zip ties) at regular intervals. Nylon cable ties are fine for this job and are what we used. Make the ties firm but not so tight that they cut into the foam. You want the lagging held securely so it won’t slip or spin. Place ties on either side of joints or bends to keep those areas tightly covered.
Reinforce the Joins and Bends:

Where two pieces of lagging meet or at sharp corners, we added an extra layer of protection by wrapping heavy-duty gaffer tape around the foam. This serves two purposes: it prevents the slit lagging from opening up at high speed. Wind turbulence under a van is strong! And, it provides a bit more abrasion resistance at the edges, so the foam isn’t torn by flying rubble. Think of it like adding “bandages” on the vulnerable spots – the tape keeps everything nicely closed and toughens up the surface.
Final Check:

Once all the foam is in place and tied, conduct a quick once-over. Ensure no sections of pipe are left exposed. Everything should be neatly bundled in its new foam armour. Verify that none of the modifications hang lower than before – the foam is thick but still squishable, and we have positioned it so that it doesn’t significantly reduce ground clearance. Trim any excess length off the cable tie tails for a clean finish. Done!

Stone proofing Your Caravan’s Grey Water Pipes: A Simple DIY Upgrade.

Cost-Effective Insurance:

The total cost of materials for my project, including foam, cable ties, and tape, was well under $100; however, it could be as low as $30-$50, depending on the size of your van and the product choices. Considering the potential cost of repairing a broken pipe or the inconvenience of being stranded without being able to use your sink/shower, this is cheap insurance. For us, using a purpose-made pipe insulation felt more durable and professional, but any padding is better than none.

In the style of a true road-travel enthusiast, we can say this: sometimes the simplest mods make the biggest difference. Cladding our caravan’s grey water pipes in foam lagging was a straightforward job that brought immediate peace of mind. We’ve essentially bulletproofed the grey water system against one of the most common sources of caravan trouble.

Reinforce the Joins and Bends where two pieces of lagging meet or at sharp corners, we added an extra layer of protection by wrapping heavy-duty gaffer tape around the foam.