Build order matters because each finished job can block access to the next one. Close a wall too early and you may forget a cable route. Finish a cupboard before planning the water system and a pipe may need to pass straight through it. Fit the ceiling first and adding a roof vent becomes a much bigger job. Before moving on, ask: if I do this now, what will it hide or block?

The right sequence depends on the van you are building. A simple weekend van and a four-season conversion with hot water, gas, solar and extra travelling seats have very different jobs to complete. What does stay the same is the dependency between them. Anything that affects the layout, weight, holes in the body or services hidden behind panels needs deciding early.

This guide focuses on those dependencies rather than repeating every part of a conversion. The three hold points are moments to put the tools down, check what is about to be hidden and decide whether the build is ready to move on.

The campervan build order at a glance

1. Decide how the van will be used and set the budget.
2. Measure the van and settle the main layout.
3. Inspect the base vehicle and shell, then deal with important faults and repairs.
4. Get a real starting weight, then plan payload, travelling seats and all major systems.
5. Make external openings and other irreversible alterations.
6. Apply bonded sound deadening to clean, unobstructed metal, then install hidden cable, pipe, duct and fixing routes – the first fix.
7. Fit insulation and the structural floor layers.
8. Line the walls and ceiling and decide when to lay the final floor finish.
9. Position bulky equipment and build the bed, cupboards and other furniture around it.
10. Complete the electrical, water, heating and other systems – the second fix.
11. Test every system, finish the trim and soft furnishings.
12. Check the finished weight, paperwork and take a shakedown trip.

This is not a rigid twelve-step recipe. The useful part is understanding why each stage sits where it does.

A practical way to use the sequence is to mark three hold points on your build plan:

• Before cutting the shell: confirm the layout, major equipment, passenger seating, external fittings and service routes together.
• Before covering hidden work: secure, label, check and photograph every cable, pipe, duct and reinforcement that will disappear.
• Before final trim: test the working systems and confirm that fuses, pumps, isolators, drains and other service points remain accessible.

If a hold point is not complete, stop there. Finishing the visible work may feel like progress, but reopening it later creates more work.

Keep a brief record before each area is closed. Note what is hidden there, how it was checked, where the photographs are stored and how you will reach anything that needs servicing. For a roof fan, for example, that could mean recording that the opening was checked against the complete roof plan, the cut edge was protected, the supply cable was secured and labelled, the fan operated and the inner trim remained removable. It need not be complicated; it just needs to be useful when the work is no longer visible.

1. Plan the finished van before you start building it

Start with the way the camper will actually be used. How many people need to sleep in it? Will anyone travel in the rear? Is it mainly for campsites with electric hook-up or for off-grid trips? Do you need a fixed bed, toilet, shower, bikes inside, a large fridge or somewhere to work?

Those decisions affect almost everything that follows. A diesel heater needs fuel, electrical power, warm-air ducting and safe intake and exhaust positions. A sink needs a tank, pump, pipework and waste route. A roof fan needs both a roof opening and a 12V supply. It is much easier to make those connections on paper than halfway through the build.

Tell your insurer that you are converting the van before major work begins and check what they need from you while the conversion is in progress. Once the van is finished, update them again with the completed specification and value.

The existing DIY campervan conversion guide is a good starting point for working through budget and the main equipment you want in the van.

2. Check the van itself before investing in the conversion

Before adding anything, make sure the base vehicle is worth building into. Review its service history and MOT record, and deal with significant mechanical faults, underbody corrosion, leaks or overdue repairs before the conversion starts consuming the budget or blocking access. If you are not confident assessing the vehicle, this is a sensible point for an independent mechanical inspection.

Then get back to a shell you can inspect properly. Remove old lining, unwanted fittings and anything else that hides the floor, walls or roof. Clean the van and look for water ingress, corrosion, damaged fixings and previous holes or repairs.

This is the point to deal with rust and leaks, because every later stage makes them harder to reach. It is also a good time to look at factory ribs, existing threaded holes and structural members so you know where furniture and services can be fixed without simply drilling wherever it is convenient.

3. Mock up the layout and check the heavy decisions

A drawing is useful, but a full-size mock-up can reveal problems that are easy to miss on paper. Mark the bed, kitchen, cupboards, toilet, water tank, battery and any large equipment on the floor with tape or cardboard. Sit in the proposed seats. Stand in the kitchen. Check whether doors and drawers can actually open and whether you can get past one another.

Before the weight plan gets detailed, put the van on a suitable public weighbridge so you know what the actual vehicle weighs in its current state. If individual axle weights are available, record those too. That gives you a real baseline rather than relying on a brochure figure that may not match an older van or one that has already been modified.

Do the weight planning from that baseline. Water is roughly one kilogram per litre before the tank, pump and pipework are counted. Batteries, furniture, passengers, gas bottles, awnings and bikes all eat into payload. Keeping the heavy items low and sensibly distributed also matters, so the layout and payload plan should be treated as one job rather than two separate calculations.

If you intend to add travelling seats or seat-belt anchorages, make that decision now. Government guidance stresses that anchorages need to withstand high crash loads and strongly recommends professional installation by qualified people. This is not something to discover after the finished floor and furniture are already in the way.

4. Plan every system before cutting the van

Before making holes, sketch the electrical, water, ventilation and heating systems together on one layout. If the van will use a fixed LPG system, include its cylinder or tank space, appliance positions, ventilation and pipe route at the same stage. You do not need every connector and fitting chosen yet, but you do need to know where the major components and routes will be.

For electrics, list the loads and decide where the leisure battery, charger, fuse boards, inverter and solar cable entry are likely to live. Our campervan electrical calculator can help size the battery, solar and inverter around the appliances you intend to use.

For water, decide where the fresh-water tank, pump, sink and waste will go and how the pipework can reach them. The water tank guide is useful here because tank position and capacity affect both space and weight.

Hold point one: do not release the shell for cutting until the proposed openings have been checked against the layout, roof space, structural members, major equipment and service routes as one complete plan.

5. Do the irreversible shell work while the van is still open

Windows, roof fans, cable glands, water fillers, hook-up inlets and heater openings are much easier to position and fit before the inside is buried under insulation and finished panels. The same applies to any openings required by a planned fixed LPG installation. Mark every opening against the real layout, then check it from both inside and outside before cutting.

Cutting metal also creates swarf and bare edges that need cleaning and protection. That work is far easier with an empty shell than with insulation, fabric and furniture underneath it. If a heater, external tank or other component needs holes through the floor, include those positions in the same planning pass.

Ventilation is part of the layout rather than an afterthought. If you are choosing a roof fan or powered vent, the campervan roof fans and ventilation guide covers the main choices and why extraction and replacement air both matter.

6. First fix: put in the things that will disappear behind the finish

Before starting the first-fix service runs, apply any bonded sound-deadening material to the clean, unobstructed vehicle skin. Cables, pipes, ducts and fixings can restrict access and make it harder to press the material firmly onto the metal.

First fix simply means installing the routes and hidden parts before the walls, ceiling and furniture make them difficult to reach. In a campervan this normally includes electrical cables, conduit where useful, water pipes, heater ducting or control cables, and any reinforcement or fixing points needed later.

Label both ends of cable runs. Leave sensible service length at the final equipment position. Photograph the routes before they disappear. A picture showing exactly where a cable or pipe crosses a rib can save a lot of guessing years later when a screw needs to go into the wall.

This is also the stage to think about access. Pumps, fuses, isolators, drain points and serviceable connections should not end up permanently sealed behind furniture. Design removable panels or reachable cupboards around anything that may need maintenance.

7. Sound deadening, insulation and the structural floor

Bonded sound-deadening material should already be fixed to the vehicle skin before first-fix cables, pipes and ducts restrict access. It does not need to cover every square centimetre to be useful; the aim is to reduce resonance in large panels rather than turn the van into a padded box.

Insulation can then be fitted around the planned services. The awkward parts of a van are the ribs, curves and doors, so there is rarely one perfect material for every surface. Our campervan insulation guide goes into the different areas in more detail.

The floor needs slightly different thinking. The structural layers — insulation where used, battens where required and the ply or other subfloor — often go in early because furniture eventually needs a stable base. Any cable, pipe or fixing that must pass beneath it has to be planned before the floor is closed.

8. Line the van, but do not bury anything untested

Once the hidden services are in place and checked, the walls and ceiling can be lined. Before closing a section, make sure the cables you expect are actually there, confirm continuity where appropriate and check that pipe routes are secure and protected from sharp edges or future screws.

Hold point two: release each floor, wall or ceiling area for covering only when its hidden work is secured, labelled, checked and photographed, and any required future access has been provided.

The final floor finish is more flexible. Some builders prefer to lay the finished floor before furniture so the surface is continuous and easy to work on. Others fit the heavy furniture first and finish around it so expensive decorative flooring is not hidden beneath cupboards. Either can work if the structural floor is already sound and the decision is made before cabinet dimensions are finalised.

If you are still choosing the surface, see the campervan flooring options guide.

9. Build the furniture around the systems, not over them

With the main surfaces in place, the bed, kitchen, seating and storage can be built and secured. Bulky or access-dependent items such as water tanks, battery boxes, heaters and larger electrical equipment may need to be physically positioned or installed as the furniture goes in, before a cabinet makes them impossible to reach. Build the furniture around those components and their service access rather than trying to squeeze them into whatever space is left.

Weight matters here as much as appearance. A cabinet that feels light on the bench is only one of many things being added to the van. Material choice, unnecessary double skins and oversized timber all add up.

The campervan cupboards and cabinets guide looks at lightweight materials, construction and fixing in more detail.

10. Second fix: fit and connect the working parts

Second fix is where the planned systems become usable. The bulky equipment that had to go in before or during the furniture build can now be connected, while lights, switches, sockets, taps, controls and other final fittings are installed. The point is not that every component waits until this stage; it is that the final connections and commissioning happen while service access is still available.

It is usually better to commission one system at a time than connect everything and hope it all works. Test a water system for leaks before closing access panels. Check each electrical circuit independently. Run the heater according to its installation and commissioning instructions before the surrounding trim makes access awkward.

If a job involves mains electricity, a fixed LPG system, passenger restraint systems or another safety-critical area beyond your competence, organise that work early enough that the installer can still reach the shell, routes and equipment before they are hidden.

11. Test it before making it pretty

Do the functional testing before the last pieces of trim, sealant and soft furnishing go in. Fill and drain the water system. Check the pump stops when it should. Test every 12V circuit. Check charging from the sources you have fitted. Confirm fans, lights, heater controls and any monitoring equipment behave as expected.

This is also a good time to look for rattles, awkward access and jobs that have become harder than expected. A removable service panel that feels unnecessary on the driveway can become very valuable when a fuse or pump needs attention on a wet campsite.

Hold point three: do not fit the final trim until the working systems have been checked and you have confirmed that service points, isolation points and removable panels can still be reached.

12. Weigh the finished camper and do a shakedown trip

Do not assume the finished conversion is within its permitted weight because the parts did not feel heavy individually. Once the build is complete, include the people, water, fuel and normal travelling kit you actually intend to carry and check the vehicle at a suitable weighbridge. Axle loading matters as well as the overall figure.

Keep photographs, manuals, wiring information and receipts for important components. Update your insurer with the finished specification and value, and deal with any vehicle details that need changing using current DVLA guidance.

Then take a short local trip before heading off for a fortnight. Use the bed, cook a meal, fill and empty the water, charge the battery and spend a night in the van. A shakedown trip can reveal small problems that are easy to miss on the driveway: rattles, doors that open while driving, poor access, condensation spots, missing hooks and things stored in completely the wrong place.

Which parts of the build order can change?

Quite a few. A heater may need to be physically mounted earlier because of access underneath the van, even though the controls and final connections come later. Some builders install the subfloor before first-fix services because nothing runs underneath it; others need underfloor routes and must do those first. The decorative floor can go under the furniture or around it. Solar panels may be fitted during the external-opening stage or later when roof work is complete.

The test is simple: will doing this job now make another necessary job much harder later? If the answer is yes, stop and resolve the dependency first.

The build-order mistakes worth avoiding

• Buying major equipment before the layout is settled. The dimensions of tanks, batteries, heaters and fridges can dictate the furniture around them.
• Closing walls before every hidden route is planned. A forgotten cable is easy to add before lining and irritating afterwards.
• Cutting holes one at a time without a complete roof and wall plan. A fan, solar panel, awning rail and cable gland can all compete for the same space.
• Burying serviceable parts. Pumps, fuses, isolators and drain points need future access.
• Leaving weight until the end. The final weighbridge check is essential, but weight should be budgeted from the layout stage onward.
• Doing cosmetic work before the systems are proven. Trim is much less painful to remove than a finished cupboard or ceiling.

Use the build order as a map, not a stopwatch

A good build order is not about racing through a fixed list. It is about keeping the next job possible. Plan the van as a complete system, stop at each hold point and leave hidden work accessible until it has been checked. The decorative jobs can wait until you know the things behind them work.

Use the linked DIYCampervan guides as each part of the build becomes relevant, rather than trying to finalise every detail at once.