How to: insulate your van conversion

Updated: Aug 27

There is a sea of information about camper van insulation online. We read through lots of different posts to try and answer the question "how do I insulate my van?", so hopefully this post can help you decide how to insulate your van conversion.

The main components you will need to insulate your camper van are:

Sound deadening (to dampen noise such as rain)

• Thermal insulation board (to fill the large cavities in the van walls)

• Rolls of wool insulation (to stuff into harder to access nooks and crannies)

Vapour barrier (to prevent condensation reaching the insulation)

Prepping your van

Before you start insulating, you'll need to completely gut your van. This involves taking up any existing floor, removing any lining and patching up any rust. This is always a very nerve wrecking part of the build, as it's everyone's worst nightmare to lift up their floor and find it covered in rust! Older Mercedes Sprinter vans can have awful problems with rust, but luckily ours is a 2013 reg and had only tiny spots of rust after cleaning away the dirt. We used some Hammerite 'direct to rust' paint to cover these areas before insulating, to ensure the rust wouldn't spread.


Sound deadening

Before installing any of the insulation, we stuck sound deadening strips to the roof and walls of the van. These are really important if you don't want it to sound like a tin can when it's raining! They take the resonance out of the panels, and deaden the sound. We used Silent Coat sound deadening strips which are super easy to apply, and easy to cut to size if you need to use them on smaller panels.

We used a mixture of 40mm thermal insulation boards and recycled bottle wool, as there are large spaces that you can fill with the boards, but there are also lots of little hard to reach places that you can fill with the wool.

Thermal insulation boards

We chose 40mm Recticel thermal insulation boards as these were thick enough to fill the cavities in the roof and walls between the beams. As we would be batoning over the beams anyway, it made sense to us to fill as much of this space as possible. There are a few different brands of thermal insulation board you can buy (Celotex, Kingspan, Recticel) but they all have very similar R values. We went for these over expanded polystyrene board because although it's more expensive, it has much better thermal properties (a thermal insulation board of 40mm has an R value of 1.8 vs. 1.05 for a polystyrene board).

Cutting these to size is super easy - you can score them to mark out sizes, and then chop them with a saw or bread knife. It's worth noting that this makes an awful screeching noise!

Recycled bottle wool

We chose to use recycled bottle wool instead of fibreglass or rock wool as it's much nicer to work with (it's not itchy and you don't need to wear a mask), and it also has the benefit of being much more eco-friendly as it's made completely from recycled bottles. We ordered ThermaFleece SupaSoft online from the Celtic Sustainables website.

We spent quite a long time stuffing the bottle wool into all of the nooks and crannies in the van. If you don't do this, it means there are huge areas of empty space in your van that aren't insulated, so it's worth spending the time trying to fit as much insulation in as possible, even if this means the slightly tedious task of posting fluff into small gaps with a screwdriver!


We built a bulkhead divider between our cab and the back of our van, mainly because of security, and also so that the back of our van would be better insulated. We decided to use 25mm insulation board for the bulkhead so that it wouldn't eat into the kitchen space too much. As we had built a wooden framework for the bulkhead, it was really easy to slot pieces of insulation into the spaces between the batons.


We were super surprised to read that a lot of people put barely any insulation on their floor. As the floor is the place you will lose a lot of your heat from, we went for 40mm thermal insulation boards on the floor. We built a stud work frame with 40mm wide batons which left room to slot the boards into. We worked out that by adding 40mm to the floor we would still have 180cm of height inside our van. As I am a tiny 5"3 and Dale is 5"11, this would mean we would maximise insulation on the floor whilst still both being able to stand up in the van.

Vapour barrier

Once all of the insulation was in place, we then covered the whole van with a huge roll of silver bubble foil insulation. This is basically like bubble wrap made from silver foil. This provides a vapour barrier between the inside of your van where you are breathing, cooking and creating condensation, and all of your lovely insulation.

We used several cans of spray adhesive to hold the foil insulation in place, and then taped the seams using aluminium foil tape.

Now that we're fully insulated the fun really starts! Next on our list is electrics and building the stud work for the bed and other wooden structures.

Here's a photo of Ringo completely 'naked', and one from after all of the bulkhead and floor insulation was finished.

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