Build in the order the van is assembled in, from the shell outward: metal, holes, services, insulation, panels, furniture, then the parts that bolt to furniture. Almost every expensive mistake in a first conversion is a step done out of order, where something cheap got buried under something that took a month to build.
Here is the sequence, and more usefully, why each step sits where it does.
1. Strip it and deal with the metal
Get the van empty. Factory floor out, any cargo lining out, seats out if they are going.
Then look at the metal honestly. Surface rust in the seams and under the floor is normal on a used van and it does not stop on its own. Treat it now, because every later step covers it. This is the one job where doing it twice means undoing the entire build.
While the shell is bare, this is also when you find out where the factory holes and captive nuts are. Those determine where you can attach things without drilling, which changes furniture layout more than most people expect.
2. Cut every hole you will ever need
Roof fan, windows, wiring glands, propane locker vents, shore power inlet. All of it, now, while the van is empty and you can reach both sides of the panel with a deburring tool and sealant.
Cutting a 14 by 14 inch fan opening in an empty van is an afternoon of measuring and about ten minutes of nerves. Cutting the same hole once the ceiling is up, insulated, and framed means removing the ceiling, the insulation, and probably a cabinet. People routinely skip the fan on the first pass because it is the scariest cut in the build, then pay for it twice. Decide the ventilation plan before you touch the roof: why a roof fan is the fix covers what the fan is actually doing.
Second holes are cheaper than second panels. If you are unsure whether you want a second fan or a side window, cut the hole now and blank it off, or accept that you probably will not add it later.
3. Rough in wiring and plumbing
Every wire that ends up behind a wall goes in before the wall does. Run it, label both ends, and leave a service loop at each fixture and each junction. Label the ends even if the run is obvious to you today, because it will not be obvious in eight months when a light stops working.
You do not need the components in hand. You do need three decisions:
- Roughly how big the battery bank is, because that sets cable size and where the heavy runs go.
- Where the battery, inverter, and distribution live, because those are the shortest and thickest cables in the van and they are unpleasant to reroute.
- Where the fridge, fan, lights, and outlets go.
Work the load out before you buy anything. Our power budget and battery sizing guides get you to a number, and the solar calculator turns that into a panel count. If you would rather size the array first, how much solar you actually need starts from the other end.
Same logic for water lines and any drain. A pipe behind a panel is invisible until it leaks, so plan access to every joint you can.
4. Insulate
Now, and not before. Insulation goes in after the wiring because it is the layer you least want to cut open again, and it goes in before the panels for the obvious reason.
The detail matters more than the material. A van shell is a continuous sheet of steel with ribs running through it, which is a thermal bridge in the most literal sense. DOE’s building science material describes thermal bridging as heat escaping wherever framing components with low R-values span from the interior to the exterior, and notes that in traditional house construction the framing alone is nearly a quarter of the wall area. In a van, the metal ribs are that framing, and they are steel, not wood.
If those ribs stay uncovered, they run colder than everything around them, and cold surfaces are where water shows up. How van insulation and condensation actually interact is the whole story, including where in the wall the water ends up and why some builds rot from the inside.
5. Panels, then furniture
Ceiling before walls, walls before floor covering, in most builds. Furniture last, because it is the only part you can realistically change later.
That is worth saying plainly: cabinets are the cheap part. If your galley is the wrong height, you rebuild a box. If your fan is in the wrong place or your insulation is trapping water, you rebuild the van. Spend your planning effort on the layers you will never see again, and accept that the furniture will get revised.
6. Install the components that bolt to furniture
Battery, inverter, charge controller, water pump, fridge, heater. These land last because they mount to things that did not exist until step 5, and because they are the parts you can service.
Leave access. Every fuse, every terminal, every pump and filter should be reachable without power tools. Builds that look best in photos are usually the ones where nothing can be inspected.
The heater is the one step with a safety rule attached
Any appliance that burns fuel inside a van produces carbon monoxide, and so does the engine. OSHA describes CO as a poisonous, colorless, odorless, and tasteless gas produced by the incomplete burning of carbon-containing material such as natural gas, gasoline, kerosene, oil, propane, coal, or wood, and states that one of the most common sources of exposure is the internal combustion engine. Its fact sheet is blunt about the failure mode: large amounts of CO can overcome you in minutes without warning, causing loss of consciousness and suffocation.
EPA’s guidance is specific and short. Do not use gasoline-powered engines or generators in enclosed spaces. Do not sleep in any room with an unvented gas or kerosene space heater. EPA also notes that CO detectors have varied in laboratory testing, with some failing to alarm even at very high levels, so an alarm is a backstop and not a plan.
The practical version for a build: a sealed-combustion diesel or gasoline air heater that draws its air from outside and exhausts outside is a different device from an open-flame heater in the cabin. Plumb the exhaust the way the manufacturer specifies, keep the intake away from the exhaust, and fit a CO alarm anyway.
What to redo cheaply, what to get right once
Get right the first time: rust treatment, roof and wall penetrations, wiring routes, insulation detailing, heater exhaust.
Expect to redo: shelf heights, drawer layout, where the shoes go, the bed.
If you are also working out where you will legally park the thing once it is built, that is a separate problem with a separate answer: what city ordinances actually say about parking overnight.