Expand your motorhome yourself instead of buying it – this is how it works

Vacationing in a motorhome has been trendy for a long time. But these vehicles are not cheap – so some people are thinking about building a van or minibus. Some types are particularly suitable, but legal requirements must be observed. And some specialist knowledge is also necessary.

Anyone traveling in a motorhome enjoys a lot of freedom: you can stay overnight wherever it is most beautiful and the travel route can be adjusted at any time. But mobile homes also have their price. Some campers therefore lend a hand and convert minibuses and vans into rolling apartments – autumn and winter are of course ideal for this. We answer the most important questions.

Which vehicle types are best suited for self-construction?

According to Dominic Vierneisel from the specialist magazine “Promobil”, panel vans offer the best basis: “The VW Transporter is most in demand here. Larger models such as Fiat Ducato, Citroën Jumper, Peugeot Boxer, Mercedes Sprinter or VW Crafter also have the advantage of headroom.” The Ducato is particularly popular because its vehicle width offers plenty of space for expansion.

But you should also keep the weight in mind when choosing a vehicle. “If the technically permissible total mass exceeds 3.5 tons, the normal car driving license may no longer be sufficient,” says ADAC spokeswoman Katharina Lucà.

What legal requirements are there and how is registration as a mobile home possible?

The main thing here is safety. Anyone can remove it, but at the end the newly built vehicle must be presented to a testing organization. The finished motorhome must be roadworthy and comply with the Road Traffic Licensing Regulations (StVZO), says Lucà. As a rule, the general operating license of the base vehicle expires as a result of the conversion.

After the assessment by a testing organization, the approval body then issues a new operating permit. Here, self-builders should make sure to register their vehicle for the “M1 SA motorhome” class. “This is not only cheaper in terms of vehicle tax, but also in terms of tolls for vehicles over 3.5 tonnes,” says Lucà.

Are there minimum requirements for expansion?

Yes, there are. In order for a vehicle to be registered as a mobile home, it must meet certain requirements: “These include a table, a seat, a cooking facility and a place to sleep,” says Altan Türk. Overall, there is talk of a “homely atmosphere” as a prerequisite for approval as a mobile home, says the testing expert from TÜV Süd. He recommends TÜV information sheet 740 to self-builders. This gives a good overview of what to pay attention to when building things yourself and what is checked.

How is the interior design planned to make optimal use of the space?

Fabian Dressler recommends starting with as precise a drawing as possible. “It should be three-dimensional and also take into account the curves of the outer walls.” This makes sense so that no space is wasted. In addition, self-builders should try to use the available space as multiple times as possible, for example with rotating vehicle seats that could also be used as chairs for the dining area. The ADAC also recommends holding preliminary discussions with a testing organization during the planning phase in order to avoid any unpleasant surprises during the final inspection.

Which materials are best suited for interior work and insulation?

Here Fabian Dressler recommends poplar plywood: “It is stable, light, relatively inexpensive and can be processed with a jigsaw or hand-held circular saw.” The surfaces can then be painted or covered with a film.

According to Dressler, felt is suitable for corner areas and can be fixed with spray adhesive. Flexible, self-adhesive PE foam mats, which are available in different thicknesses, are best suited for insulation. Mineral wool is also possible, but it is not so convenient to process.

How can you implement power supply and lighting in a motorhome?

Two solutions are available for power supply: centrally with an additional battery or decentrally with powerful batteries in appropriate places, for example in the lighting. “A central supply is convenient, but the installation is more complex. You have to pull cables and protect the circuits,” says Dominic Vierneisel. In this case, he recommends involving a specialist in the planning. A good compromise can be a power box in which the storage battery, charger and various connections are already integrated.

What about running water and a toilet?

A small sink is standard and can be installed with a canister or a fixed tank. A pump is also required for this. “If you don’t spend a lot of time on campsites, you should also plan for a toilet,” advises Vierneisel. A cassette toilet requires a water flush, whereas separation toilets do not. If you want to put in more effort, plan a shower too.

Which safety regulations must be observed?

When it comes to kitchen expansion, among other things, camping enthusiasts shouldn't choose the first stove they come across. “It has to be a model that is suitable for indoor use and has approval for this,” explains expert Altan Türk. Windows and roof hatches that are installed must also have appropriate approval, otherwise they will fail the vehicle inspection. Türk also points out that a mobile home must have forced ventilation that ensures air exchange.

What avoidable mistakes often occur when building things yourself?

According to Türk, hobby builders sometimes do not take into account that load-bearing parts can be damaged when installing a window or a roof hatch, for example. “In addition, certain minimum distances must be maintained during interior design, for example around the hob. Things like this are often forgotten.” If in doubt, says Türk, self-builders should ask the testing organization in advance.

Where can you find blueprints and instructions for building a mobile home yourself?

The Internet is an almost inexhaustible source for this. There are also numerous videos on the subject on YouTube. There are also books on the subject of “expanding your own motorhome”.