A van conversion goes smoothly when you work from the outside in and from the hidden to the visible: plans and regulatory checks, cutting and structural changes, insulation, cable runs, floor, wall and ceiling lining, electrics, furniture, water, and finally gas and its certification. Each stage covers up the one before it, so a cable forgotten behind a finished panel means taking the lining down again. No standard sets this order. It is a workshop logic, and this guide walks through it using the approval requirements of a French DREAL and published guidance from manufacturers and the motorhome press.
1. Cutting and structural changes come first, with the manufacturer’s agreement where approval rules require it.
2. Insulation, cables and conduit go in before the floor and the lining.
3. Furniture is fixed rigidly, and the gas system is certified before any approval inspection.
Step 1: draw up the van conversion plan
It all starts on paper. In France, the DREAL Pays de la Loire asks for dimensioned drawings and photos in its approval file for converted vans, so it makes sense to produce them from day one: they guide the build and double as paperwork. Place the bed, kitchen, storage and seating, then the technical kit: battery, tanks and the gas bottle if you plan one.
This is also the moment to decide what the van will be on paper. If you are converting a French-registered van and want it approved as a motor caravan, it will need, as a minimum, seats and a table, sleeping accommodation, cooking facilities and storage, all rigidly fixed, as our guide to VASP registration in France explains. In the UK, check the current DVLA rules for your own registration before you finalise the layout.
The plan also has to account for weight. The DREAL weighs a van in running order, with tanks at least 90 % full and a full gas bottle. Every unit, every battery and every litre of water eats into the remaining payload, so a layout that keeps heavy items low and close to the axles starts off on the right foot.
Step 2: cutting and windows for a van conversion
For this part of the van conversion, anything that involves the bodywork comes first, because it throws off swarf, leaves cut metal edges to treat and changes the shape of the walls you will insulate. That covers windows, roof lights, the roof fan, ventilation openings and, if you are fitting one, a pop-top roof.
The DREAL sets conditions on several of these jobs. Added windows must be approved glazing with a marking. Cutting the bulkhead between cab and living area needs the manufacturer’s authorisation or proof of strength. And the DREAL Pays de la Loire approval sheet for converted vans requires the manufacturer’s agreement for structural changes such as a pop-top roof or modified suspension.
The German magazine Promobil gives the same warning in its feature on a self-built panel van conversion: under German rules, the vehicle’s operating permit lapses once the roof is converted. Wherever you are registered, get written approvals before you start cutting.
Step 3: insulate before the rest of the van conversion
Once the metal is cut and its edges treated, insulation can begin. It should cover the metal continuously, with no bare patches, since condensation forms on cold surfaces. The material and thickness depend on how you will use the van, and our comparison of cork and Armaflex for van insulation sets out two options side by side.
Think now about the air that will need to move behind the furniture and under the bed. Our guide to campervan condensation explains why those airless corners collect moisture and how to plan for them in the layout.
Mark on the insulated walls where the furniture fixings will go. A unit that has to be rigidly fixed screws into something solid, so add battens or reinforcement at those points before you close the walls.
Step 4: cables and conduit for a van conversion
Before a single lining panel goes up, pull every electrical cable and lay conduit for future water pipes. This is the step that needs a finished wiring diagram: where the battery, busbar, fuses, 12 V and 230 V outlets, lights and solar panel will sit.
Our guide to the campervan wiring diagram sets out the order of components and how to protect each circuit. Run spare conduit to areas where you might add equipment later: an empty conduit costs little during the build and saves taking down a finished panel.
Photograph each wall once the cables are in, with a tape measure visible in the shot. Those pictures help you find a cable behind a panel later, and they add to the photos an approval file asks for.
Step 5: floor and lining for a van conversion
The floor comes next. In the conversion Promobil followed, it went down with rails, straight after the roof conversion. It is the base everything else will stand on.
Lining the walls and ceiling follows the floor. Promobil places it at this stage, just before the furniture and the bench seat, which fits the hidden-to-visible logic: by now the insulation and cables must be finished and checked, because the panels are about to cover them.
Leave access hatches in the right places: behind the battery, at the fuse box, at water connections and where cables run up to the roof. A removable panel in those spots saves a lot of time the first time something goes wrong.
Step 6: electrics and furniture for a van conversion
For this stage of the van conversion, with the walls closed, the main electrical kit goes in: battery, solar charge controller, charger and inverter. To size each one, our guides on how to size a van battery bank and on choosing a van inverter take you through the sums step by step.
The furniture follows, starting with the heaviest and lowest units: bed base, kitchen unit, bench seat. Fix each one rigidly to the structure, since that is a condition of motor caravan approval in France, where only the table may be removable. Keep the technical kit housed inside those units easy to reach.
Step 7: water and gas to finish the van conversion
The water system goes in with the kitchen furniture: fresh water tank, pump, tap, sink and, if you are fitting one, a waste water tank. Mount the tank low and near the axles for weight distribution, and remember it will be weighed at least 90 % full for a French approval.
Gas comes last, once the furniture is in, because it has to be certified. The DREAL requires compliance with EN 1949 for the liquefied petroleum gas installation and EN 721 for safety ventilation, confirmed for a self-builder by an approved body, either the Qualigaz association or Bureau Veritas.
A Truma training document on EN 1949, in its 2009 version, gives a feel for these requirements: gas bottles stand upright, secured, in a locker sealed off from the living space, with a low vent of at least 2 % of the locker’s floor area and no less than 100 cm². The same document says the installer should issue a certificate of conformity with the standard for every vehicle. As that material dates from 2009, have your installation checked by the certifying body against the current version of the standard.
Your van conversion schedule by type of build
| Build | Order to follow |
|---|---|
| Light build with no gas and no cutting | Plan, insulation, cables, floor, lining, electrics, furniture, water |
| Full build with windows and a gas kitchen | Plan and approvals, cutting, insulation, cables and conduit, floor, lining, electrics, furniture, water, certified gas, weighing |
| Pop-top roof or walk-through | Written manufacturer approval before any cutting, then the full order above |
Whatever the size of the project, the rule for a van conversion stays the same: anything that will be hidden gets finished and checked before it is covered. The drawings, the photos of each stage and the certificates you collect along the way end up forming most of the approval file.