Standard vans are not designed to provide the warmth and comfort we expect from a camper. That means insulating your van conversion is one of the first things you need to tackle. It’s a core element of any conversion and the space and configuration it takes up can influence everything else you do.
If you’re planning a DIY van conversion, getting your insulation right can genuinely make or break the project.
With that in mind, we’re covering all the basics of van conversions and insulation to give you an idea of just what to expect.
Why do van conversions need insulation?
The thin steel shell of a typical van has not been designed for heat retention or to protect the occupants from overheating. It’s there to provide structural integrity and to protect the cargo.
That means you have to make the van suitable for humans, which is where insulation comes in.
Insulation helps prevent your van overheating in direct sunlight. It also helps prevent heat escape once you’re inside. It can also provide sound insulation from the surroundings when you’re trying to sleep.
All essential characteristics of a successful camper van conversion!
Selecting your insulation material
Ideally, you want your van insulation to be light, easy to fit, moisture, mould and sound resistant and have as high an R value as possible. The higher the R value, the more heat it can keep in or out of the van.
You also want your material to be space efficient. Interior space is at a premium so you don’t want to be using rolls of insulation from your loft!
We generally see two types of insulation in a van conversion. Closed-cell polyurethane spray foam and Polyisocyanurate foam board.
Closed-cell polyurethane spray foam – Closed-cell polyurethane spray foam is a foam you can use to cover the interior of your van. It has a very high R value, is easy to install and minimises air gaps. The downside is that it can be expensive.
Polyisocyanurate foam board – Polyisocyanurate foam board is relatively inexpensive and has a high R value. It is also readily available and fairly easy to use. The downside is that you have to be very careful when fitting to avoid air pockets.
You can also use a combination of these two products. The foam board for large areas and the spray foam to fill gaps and cover any awkward areas.
You can also use Rockwool or other home insulation. Just select the type and size carefully to not over-insulate the van. If you choose to use household insulation, make sure there is adequate ventilation as a van doesn’t breathe like a building does!
Low-E Insulation is also a viable alternative. It’s thin, comes in easy to manage reflective sheets and can be moulded and cut into all kinds of shapes. We are increasingly seeing this type of insulation used in van conversions and reviews have been very positive.
Finally, good old sheep’s wool is also a viable option. It doesn’t have the R value of foam or foam board but it’s breathable, sustainable, a good sound barrier and can even help manage condensation.
How much insulation will you need for your van conversion?
If you have an idea of what to use as insulation, you’ll now need to figure out how much you’ll need. This will, of course, depend on your donor van and the types of climate you’ll be travelling in.
As an example, a Volkswagen Transporter short wheelbase measures 4.37m roof x 4.37m floor x 9.65m for walls. A long wheelbase Transporter has 5.06m roof x 5.06m walls x 10.79m walls.
Plan for more than that to give you spares for fitting into small spaces or for mistakes.
Other vans will obviously vary but a quick measure of the interior should give you the numbers you need.
For temperate climates like the UK and Europe, you can use standard insulation for between -10 and +35C. If you’re planning on venturing to colder climates, you’ll want to increase that accordingly.
Should you use a moisture barrier?
The question of using moisture barriers is one of the liveliest conversations you’ll have. It’s a question with no definitive answer as everyone’s opinion is different.
We think you don’t need one if you use foam spray, sheet or sheep’s wool. As long as you install it correctly and ensure there are no air gaps behind the insulation, you should be perfectly safe.
Just remember to use spray or tape to seal any joins or fill gaps.
Ventilating your van conversion
Any vehicle you intend spending time in needs insulation. Humans radiate heat and moisture and add cooking, drinking and general living to that and you’ll have a genuine requirement for good ventilation.
Plan on having at least one good sized vent in the ceiling. While it will let heat escape, it will also allow moisture to escape and the air to be refreshed. Two things you’re going to want in your conversion!