DIY: Underside Caravan Protection

John Hughes — 26 November 2021
We caught up with Andrew Phillips and the team from The RV Repair Centre to give us the run down on protecting your van

Ensure the van cannot roll or fall on you while you are under it by always using the following precautions:

• Park the van on level ground with the tow vehicle detached

• Engage the park brake and ensure it is functioning correctly

• Chock the van wheels

• Place axle stands under the A-frame as a back up to the jockey wheel

• Lower all of your stabilisers

It is also a good idea to have someone else around to get help if something did happen to go wrong. Even if nothing goes wrong, it is handy to have someone who can pass you things while you are lying under the van.

Often, the van will be dirty underneath, so safety glasses will make the job much more pleasant and safe when you dislodge dirt. If you plan ahead, you can wash the underside of your van and allow time for it to dry. You are going to need to do a fair bit of cutting. Using something like some wide opening snips will be safer than working with an open blade.


Have a good look under your van and identify wires, plumbing or fittings that appear to be exposed. In the case of wiring, it could be routed to your brakes, stability control or your lights, among others. Flexible conduit is the go-to method for protecting wires. It is corrugated so it has some impact resistance and can bend easily wherever you need it to go. It is also slitted so that you can easily feed the electrical wire into it.

Flexible conduit is available in various diameters. Select a diameter (you may need more than one) that will enable the wiring to be encapsulated snugly without having to stuff it in. To roughly measure the total length, you need just follow the lines with a tape measure and add all the sections up.

The plumbing could be rigid PVC pipe or flexible polyethylene pipe. Identify the diameter of the pipes and the lengths you will need. To protect plumbing, you could use flexible conduit or a foam sleeve — either plumbing lagging or pool noodles. Plumbing lagging is convenient as it comes pre-slit and is usually a subtle dark colour. Pools noodles seem to be universally brightly coloured and may or may not have the pre-slit.

Some vulnerable points, such as taps and protruding plumbing fittings, can’t be covered with a protective sleeve. An aluminium guard or rubber flap can be a good solution.


Wiring and plumbing are usually clipped to the chassis with clamps or cable ties to keep things tidy. It may be necessary to temporarily unclip the wiring or plumbing line to enable it to be fed into the flexible conduit. It may also be necessary to replace original clamps with larger clamps to accommodate the increased diameter conduit.

The flexible conduit should be fitted in the most continuous lengths possible for maximum protection. If you are working with a long line, just roll out the conduit and feed the wire into the slit as you go. Then, cut off the conduit when you reach a juncture, being careful not to cut the wiring or plumbing, or yourself! For short lines, it is possible to measure out each length simply by holding the conduit up to the section you want to cover, mark with a white pen, and cut with snips or electrical side cutters.

Remove the clamps holding the plumbing in place


Usually, you will be able to measure by holding up your protective sleeve up to the pipe, making a mark and cutting. Cutting notches in the foam will enable you to accommodate plumbing fittings. Simply slide the protective sleeve over the plumbing lines and secure with cable ties.


Creating an aluminium guard can be as simple as putting a couple of folds in a sheet of metal and attaching to the A-frame or chassis. First, you will need to identify if there is a potential mounting point. In this instance, the manufacturer opted to drill holes in the A-frame to mount the guard.

To replicate this guard, measure up some dimensions and make a template out of cardboard complete with folds. Hold the folded cardboard in position to ensure it will fit and provide adequate protection. Flatten the cardboard out and use this as a template to cut out your aluminium sheet. A nominal thickness of 2mm should provide adequate protection and be practical to cut and fold. A good pair of snips could be used to do the cutting. Any sharp edges can be deburred with a file. The folding can be done by clamping up against a block of wood and bending by hand. This guard was originally mounted with pop rivets so that’s what we used to put it back.


Other vulnerable points, such as a plumbing fitting, a side step or stabilisers, can be protected with a rubber flap. This can be a simple solution given there may be no fabrication required — it's often a matter of finding a method to attach the flap. In this instance, we relocated a plumbing fitting to behind a chassis member so it could be used as a mounting point for the rubber flap. The flap can then simply be screwed on.


A good deal of discretion is required when drilling holes and adding fasteners to your caravan. There could be wires or plumbing hiding behind where you plan to drill. Proceed with caution and do not drill any deeper than you need to. Also think about whether the fastener could penetrate wires or plumbing.

A large enough hole or too many holes could compromise the integrity of your chassis or A-frame — we unfortunately can’t tell you where to draw the line on this. Drilling holes breaks the protective surface on metal, possibly leading to corrosion. Any holes created should be ‘painted’ with suitable corrosion protection.

You need to be careful selecting fasteners that are made of a suitable metal. Using an incompatible fastener material (dissimilar metal) can promote corrosion. There is a whole science to this beyond the scope of this article.

Plumbing fitting well protected by rubber flap


Improper maintenance could lead to injury, death or property damage. Maintenance work of this nature should only be undertaken by persons with suitable mechanical competence. Information provided is general in nature and can only be taken as a guide. Individual discretion must be exercised and persons undertaking described tasks do so completely at their own risk. Publishers and creators of this content accept no responsibility for loss or damage.

Thanks to Andrew Phillips and the team from the RV Repair Centre, 120 Canterbury Rd, Bayswater North, VIC 3151. Ph: (03) 9761 4189 


How to DIY Underside protection Caravan


John Hughes