Motorhome & Campervan Chassis Repair Ireland
Motorhomes suffer chassis rot in a way that catches owners completely off guard. The van has low mileage, it looks presentable, the habitation inspection passed fine - and then the CVRT inspector puts it on a lift and finds the front cross-member is gone.
This is not unusual. It is, in fact, one of the more predictable failure patterns in Irish motorhome ownership - and it comes down to how Fiat Ducato-based motorhomes are built, how they are used, and where Ireland sits climatically.
Quinn Engineering in Omeath, Co. Louth repairs motorhome and campervan chassis corrosion. This post explains what goes wrong, where, and why.
The Ducato Platform and Why It Rusts
The vast majority of coachbuilt motorhomes on Irish roads - regardless of brand name on the side - are built on the Fiat Ducato platform. Peugeot Boxer and Citroen Relay are the same vehicle with different badges (all three come from the Sevel joint-venture factory). A Rapido, a Chausson, a Swift, a Benimar, a Hymer built on the Ducato base - they all share the same donor chassis underneath the habitation body.
Pre-2007 Ducatos were not fully galvanised. The chassis received a zinc phosphate primer, some underseal, and that was about it. In practice, on a vehicle that spends its winters sitting outside with water trapped in box sections, that protection is gone within a decade. Post-2007 models improved the corrosion treatment but did not eliminate the problem - they rot more slowly, and they still rot at the drainage points.
The reason it stays hidden is simple: the habitation body sits over the chassis. You cannot see the steel structure without getting under the van on a lift. Most motorhome habitation services do not include a proper underbody inspection. Owners drive for years assuming everything is fine because nothing has failed yet.
Where the Rot Starts
Not all areas of a Ducato chassis rot equally. Some spots are predictable enough that any experienced welder can tell you what to look for before the van even goes on the lift.
Front cross-member. This is the most common serious failure point. The front cross-member sits below the engine, connecting the two main chassis rails across the front of the van. The windscreen scuttle area drains water directly onto it. On an older motorhome, this cross-member is frequently perforated or structurally compromised. It is load-bearing and directly relevant to how the van handles front-end impacts.
Inner front wings and arches. The inner wings on Ducato motorhomes trap mud and moisture against steel that is difficult to reach and treat. This area corrodes from the inside. By the time bubbling shows on the outside, the inner steel can be seriously thin.
Sills. Box-section sills on the Ducato are a known weak point. They fill with water, the drains block, and the steel rots from inside out. A tapped sill that sounds solid can have paper-thin steel at the bottom if the inner face has corroded.
Chassis-to-subframe joins. Where the main chassis rails connect to the rear subframe section, bolted and welded joints trap debris and moisture. These areas are high stress points and corrosion here is a structural concern.
Suspension tunnel and strut tops. The front suspension sits in a pressed-steel tunnel. Water sits in the low points of that tunnel and corrodes the steel from the top face down - meaning the rot is on the inside, not the face you can see on a cursory look.
Jack points. Reinforced areas on the sills designed for the motorhome’s steadyleg jacks. These take load every time the van is levelled. Corroded jack points fail under load and are a direct safety issue.
If your motorhome is a pre-2007 Ducato base and has not had a proper underbody inspection in the last few years, most of these areas warrant a look.
The AL-KO Question
Many coachbuilt motorhomes - particularly German and French models from the 1990s and 2000s - use an AL-KO chassis extension at the rear. The AL-KO section is often hot-dip galvanised and holds up considerably better than the forward Ducato chassis sections.
This confuses owners who have read about AL-KO durability. The AL-KO piece is one component. It bolts and welds to the standard Ducato chassis rails, which are not galvanised to the same standard. You can have a perfectly sound AL-KO rear section and a seriously rotted Ducato front chassis on the same vehicle. Inspecting only what is accessible without lifting the van properly will miss the forward sections entirely.
Our underbody welding work on motorhomes starts with a full inspection on the lift - the AL-KO section, the Ducato chassis rails forward of it, the front cross-member, and everything between.
Why CVRT Catches What Owners Miss
Motor caravans require an annual CVRT test. The 2026 fee for a 2-axle motor caravan is EUR 108.72. The test includes a full visual inspection of the chassis, underbody, suspension, and braking system with the vehicle on a ramp.
CVRT inspectors are not lenient about chassis corrosion on structural members. If the metal does not feel firm under pressure, or if there is a hole or serious thinning on a load-bearing section, that is a fail. Structural chassis corrosion can be graded as a Dangerous defect - the highest category, which means the vehicle cannot legally be driven from the test centre.
Motorhomes that have not been regularly tested, or that have had habitation-only services for years without a proper underbody look, are the ones that tend to produce genuinely alarming results when they finally go on a CVRT lift. The rot has had time to spread.
If your motorhome is due a CVRT, or if it failed on underbody corrosion, getting the structural welding done properly is the path back to a pass. Body filler over structural rust does not pass; welded-in new steel does.
The Salt Air Factor on the Cooley Coast
A lot of motorhomes stored and used in the Carlingford and Cooley Peninsula area spend time parked close to Carlingford Lough - a tidal sea inlet with a 4-metre spring tide range. Coastal salt air is a proven accelerant for steel corrosion. It is not catastrophic on its own, but on a vehicle that already has compromised underseal and drainage issues, the coastal environment speeds up what was already happening.
Owners who store their motorhome near the shoreline between Omeath and Carlingford, or who tour regularly along the R173 coast road, are in a higher-corrosion environment than an equivalent vehicle kept well inland. This is worth factoring into how often you get the underbody inspected.
Engine-Out Access
Some motorhome chassis repairs - particularly to the front cross-member - cannot be done properly without removing the engine. The cross-member sits under a lot of ancillary equipment. Getting it out to cut and weld in new steel requires the engine and radiator to come out first.
This is not something every workshop will tell you upfront, but it is the honest reality of doing the job properly on a badly corroded Ducato front end. Attempting to weld a new cross-member in without proper access produces poor-quality joins in a highly stressed area. We assess access requirements during inspection and let you know what is needed before any work starts.
Repair Costs - What to Expect
Motorhome chassis repair costs vary significantly depending on how much rot is present and how many areas need attention. As a market reference: structural underbody welding jobs on commercial-size vehicles in Ireland typically start around EUR 2,000 for a single major area, and multi-area repairs can run to EUR 3,000-6,000 or more depending on scope.
We do not quote blind and we do not quote by the area name. The inspection tells us what steel needs to come out, what needs to go back in, and what access is required. Call for a quote once we have had a look.
For context on what chassis repairs involve more broadly, that page has a plain-language explanation of the work.
What Happens If You Leave It
Chassis rot does not stabilise. What is a single perforated cross-member this year is a cross-member plus both front sections of the chassis rails next year. The longer it is left, the more steel has to come out, the longer the job takes, and the higher the cost.
There is also the safety question. A motorhome carrying passengers with a structurally compromised front chassis is not a safe vehicle. The front cross-member is load-bearing in a front collision. This is not a comfort-and-convenience issue; it is structural integrity.
The CVRT exists partly to catch exactly this. But the test is annual, and a lot can change in 12 months if rot is already present.
Get It Inspected
Quinn Engineering is in Omeath on the Cooley Peninsula - roughly 20 minutes from Dundalk, 10 minutes from Carlingford, and easy reach for motorhome owners across north Louth and into south Armagh.
If your motorhome is a Fiat Ducato, Peugeot Boxer, or Citroen Relay base - any age, any brand built on that platform - and it has not had a proper underbody inspection in the past couple of years, it is worth getting it checked before the CVRT flags it for you.
Send photos of any visible rust to WhatsApp and we can give you an initial read before you make the trip: wa.me/353838077144. Or call Stephen directly on 083 807 7144.
We also cover whether underseal is worth applying after chassis repairs are done - worth a read if you are deciding what to do once the structural work is complete.
Frequently Asked Questions
Why does a low-mileage motorhome still have serious chassis rust?
Mileage has almost nothing to do with it. Motorhomes typically do 5,000-8,000 miles a year, so a 15-year-old van might have only 90,000 miles on the clock - but it has been sitting damp, parked outdoors, with water draining straight onto the front cross-member for 15 winters. Rust is driven by time, moisture, and drainage, not by kilometres.
The AL-KO sub-frame on my motorhome is galvanised - does that mean the chassis is OK?
No. The AL-KO rear chassis extension fitted to many coachbuilt motorhomes is often hot-dip galvanised and holds up well. But it sits on top of a standard Fiat Ducato (or Boxer/Relay) donor chassis, which is not galvanised in the same way - especially pre-2007 models. That underlying Ducato chassis can be badly rotted while the AL-KO section above it looks fine.
Does a motor caravan need a CVRT test?
Yes. Motor caravans require an annual CVRT (the test that replaced the old DoE test). The 2026 fee for a 2-axle motor caravan is EUR 108.72. The visual underbody and chassis inspection is part of that test. If the inspector finds structural corrosion, the vehicle fails.
Can you do the chassis repair without removing the engine?
Sometimes, but not always. The front cross-member - one of the most common rot spots on Ducato-based motorhomes - sits directly under the engine and radiator. Full access to weld in new steel often requires the engine to come out. We assess each vehicle individually and only do what the access genuinely requires.