Van conversion build order: the sequence that avoids redoing work

A van conversion is a stack of layers, and each layer buries the one beneath it. Cables disappear behind insulation, insulation disappears behind cladding, cladding disappears behind cabinets. That's the whole reason a build order exists: it isn't tradition or preference, it's the physical fact that step 8 makes step 4 unreachable. Get the sequence wrong and the cost isn't doing a job twice — it's tearing off finished work to reach the job you skipped, then redoing the finished work as well.

Here is the canonical sequence, step by step, with the reasoning attached to each one so you can tell when it's safe to deviate — and when it absolutely isn't.

1. Plan the complete layout — before touching the van

Not a sketch of the bed. The complete layout: bed, kitchen, seating, water tanks, battery bank, garage, every cabinet. The reason is buried in the steps below — you can't wire for a kitchen you haven't placed, cut a flue hole for a heater without a fixed position, or route a waste pipe to a tank that doesn't have a home yet. Every downstream step consumes decisions made here. The layout planning guide covers the method in full; what matters for build order is that this step ends with dimensions, not vibes.

Doing this digitally pays twice: place the full layout in 3D and you get the wiring and plumbing run lengths, plus a cut list for the ply, before you've bought a single sheet. VanPlot does exactly this, free in the browser — real van interiors, real furniture dimensions, and the measurements fall out of the model.

2. Rust repair and mechanical work

The van is never more accessible than it is right now, empty. Grind back and treat every rust spot, especially the wheel arches, sills, and floor seams that will spend the rest of their life sealed under insulation and ply. Sort the mechanical basics — brakes, timing belt, leaks — while a workshop can still get a lift under an unloaded van. Rust discovered under a finished floor two years in is the single most demoralising fault a converted van can develop, because everything above it has to come out.

3. Cut every hole while the van is empty

Windows, roof fan, heater flue, gas drop-out, fridge vents, water fill, tank outlets, shore-power inlet. All of them, in one phase. Cutting sheet metal throws hot swarf in every direction — swarf that rusts wherever it lands and burns wherever it sticks. With an empty van you can vacuum every shaving and treat every cut edge. With an insulated, clad van you're cutting blind into a wall you can't inspect from behind, hoping the jigsaw doesn't find a cable. Positions for all of these holes come from step 1: the flue goes where the heater goes, the vents go where the fridge goes.

4. First-fix wiring and plumbing runs

“First fix” is the trade term for everything that lives inside the walls: cable runs, conduit, water lines, and the holes through ribs and bulkheads they pass through. This all happens before insulation — the runs follow the bare metal channels of the van, and once those channels are stuffed with wool or foam, threading a cable through them goes from a five-minute job to an archaeology project. Run more than you need: an extra 12 V feed and a spare network of conduit cost almost nothing now and are nearly unbuildable later. Label both ends of everything. Leave generous service loops at every appliance position — positions you know, because of step 1.

5. Sound deadening, then insulation

Butyl deadening pads go directly on the large flat panels first — they need bare metal to bond to. Then insulation fills the cavities around your first-fix runs. Whatever material you choose, the order logic is the same: this layer entombs the wiring layer, so the wiring layer must be finished, tested for continuity, and photographed before the first batt goes in. Photograph everything — a phone picture of every wall with the runs visible is the cheapest as-built documentation you will ever make.

6. The vapour barrier question

Honest answer: the van-build world does not agree, and both camps contain competent builders. The sealed-barrier camp argues that a continuous membrane keeps moist air off the cold metal entirely. The sceptic camp argues that a perfect seal is unachievable in a vehicle that flexes, and an imperfect barrier traps moisture worse than no barrier — so they prioritise ventilation and materials that tolerate moisture cycles. What everyone agrees on: don't leave open gaps where warm humid air can freely reach cold steel, keep the van ventilated, and whatever you decide, decide it now, because this layer is about to be sealed behind cladding forever.

7. Floor

Insulated subfloor, ply, then the finish surface, run wall to wall. The floor goes down before walls and before furniture because everything else stands on it. Lay it in full sheets across the whole footprint — resist the temptation to save material by flooring only where furniture won't sit. A continuous floor lets you move or rebuild furniture later; a patchwork floor means every future layout change starts with floor surgery.

8. Wall and ceiling cladding

Ply, tongue-and-groove, or carpet-lined panels — this is the layer that turns a metal box into a room, and it seals in everything from steps 4–6. Before the last panel goes on, stop and test: energise every circuit, pressurise the water lines, check the fan and every vent. This is the final moment any of it is reachable without a crowbar. Walls before furniture, because scribing cabinets to a finished wall is straightforward; cladding around installed cabinets is a jigsaw of offcuts.

9. Furniture carcasses

Now the boxes go in: bed frame, kitchen unit, wardrobe, seating plinths — structure only, no doors, no worktops yet. Each carcass gets fixed through the cladding into the ribs or floor anchors behind it (which you noted in step 4, before they vanished). This is the step where a digital plan pays off most visibly: cabinets designed against real interior wall curvature, with a cut list generated before this phase started, assemble like flat-pack instead of trial-and-error.

10. Electrical second fix and gas

Second fix is everything that attaches to the ends of the first-fix runs: sockets, lights, fuse board, battery bank, charger, pump, heater, hob. It comes after furniture because most of this hardware mounts in or on the furniture — the fuse board in a cabinet, the sockets in the kitchen face, the pump under the sink. Gas work belongs to a qualified installer in most jurisdictions, and the drop-out holes and pipe routes they need were cut in step 3 and planned in step 1. If budget is forcing you to stage purchases, this is the step where sequencing money matters most — the cost breakdown covers what to buy early versus what can wait.

11. Soft finish and test trips

Doors, drawer fronts, worktops, upholstery, trim. Then — before any of it feels precious — go camping. Short trips, bad weather, real cooking. Every build has a list of things the first three trips expose: a drawer that opens under braking, a light switch in the wrong place, a bed that's 5 cm too short. Finding them while the trim screws are still fresh is the difference between an evening's adjustment and living with it.

The classic out-of-order mistakes

Every one of these appears weekly in build forums. The pattern is always the same: enthusiasm for a visible step overtakes an invisible one.

What you can safely run in parallel

The sequence above is a dependency chain, not a calendar — plenty of work happens off-van, out of order. Furniture carcasses can be prototyped and even fully built in the workshop while the van is still at the insulation stage, provided the dimensions come from a finished plan rather than from measuring installed walls. The electrical system is the classic example: mount the fuse board, bus bars, charger, and inverter on one ply board on the bench, wire and test the whole assembly at leisure, then install it as a single unit at step 10. Cushion covers, window blinds, and worktop finishing are all winter-evening jobs that never block the chain. The only rule: parallel work consumes the plan, never improvises past it.

The sequence, compressed

Plan everything, fix the metal, cut the holes, run the wires, insulate, floor, clad, build, connect, finish, test. Eleven steps, one direction, and the expensive mistakes all come from running it backwards. The cheapest insurance is making step 1 genuinely complete — a full layout with real dimensions, run lengths, and a cut list — before a single hole gets cut. That part costs nothing but an evening.