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How to Install Insulation a DIY Camper Van Conversion

We really wish we could say there was an easy Sprinter Van Insulation Kit that made everything streamlined and simple.  But there’s not…


That’s a great question; I’m glad you asked!  If you’ve done any research at all on how to insulate a campervan, you know that there are approximately 1.73 million ways to do it.  And no one actually thinks their way is the best way.  So, we’ve decided that the best way to insulate a van is to pick one direction and stick to it!  You can go crazy researching for hours, days, weeks and still not be sure you’re doing it “right.”  The best insulation is insulation that is installed.


Total Project Cost: $410.63


This process is a long process; it took us over a week working on it every single day and at least one 12-14 hour day.  It seems like to took forever, but it’s done, finally!  So don’t get in a hurry and just take your time.  Here’s the step by step:

Clean the surfaces:   Since we are using spray adhesive, we need the surface to be free of dust so that the 3M Super 77 adhesive has something clean to stick to.  We just used a vinegar solution for this and made sure it was dry before moving on.

Measure Twice, Cut Once: Okay, in this situation that isn’t really all that necessary.  Just measure enough to get close because your pieces are going to need to be trimmed in place anyway.  We used 1-inch RMax Rigid Foam on the ceiling and walls as the first layer and 1/2-inch RMax for the second layer, giving us 1 1/2 inches of insulation around the ceiling and walls.  We chose this because that is the depth of the cavities in both the ceiling and walls, so we wanted to maximize our insulation space. For the floor, we used only 1/2-inch foam so we wouldn’t lose too much height in the van.

The larger parts of the van were pretty simple to measure and cut, but the smaller nooks were much more difficult.  We found that cutting a ton of 5″ x 5″ squares and using them as little tetris pieces was much easier than trying to perfectly fit each piece.  That saved us a ton of time trying to get perfect fits into small, awkward places.

We ended up using 9 sheets of the 1/2-inch RMax and 7 sheets of the 1-inch rigid foam, with plenty of scraps left over.

Glue the Insulation: Using the 3M Super 77, we started with the ceilings and sprayed generously on the metal and on the back of the insulation.

Brace the Insulation: Once the insulation was stuck in place, we used some scrap wood to brace it up while the glue cured.  It was necessary to do this for the ceiling and for the large parts of the walls, but the smaller parts of the walls stayed in just fine without the bracing.

Fill the Cracks: Using Great Stuff spray insulation, fill in the cracks and other spots that were missed by the rigid foam.  Another great reason we used spray insulation was for extra support for the rigid foam.  After spraying the edges of the RMax with Great Stuff, it sealed nicely and isn’t going anywhere.  Remember that the Great Stuff expands quite a bit, so be sure to test a spot somewhere and see how much it expands before spraying all of the crevasses.  Pro Tip: If you get the Great Stuff on you or if it drips somewhere, DO NOT try to wipe it up.  Just let it dry where it dripped and then you can peel it off easily, even on your skin.  Wiping it up will just make a big mess and it will never fully come off.

Trim the Edges: Using just a box knife or a hacksaw blade, we trimmed off any excess expanding foam insulation and made sure the walls would fit flush when we installed them.

When it was all said and done with, we still aren’t sure if our way was the best way to insulate a campervan, but it’s done and that’s all that matters!

mehrdad jamnejad-dalamie

Monday 27th of April 2020

Any worries about mold, since there are some airpockets behind the polyiso foam boards afterall? Especially in the big panels where the windows in a passenger version go there are thin trusses of metal in the middle. Does it matter as long as you've sealed around the foam boards with Great Stuff?

Nate Yarbrough

Friday 8th of May 2020

I'm not too concerned about it.

Doug Stamler

Thursday 19th of March 2020

HI Nate. & Steph . Nice job & loads of good info . Some people need to step back & think for a few seconds before they commenting . Yes any job we undertake for the first time , is time consuming & a learning curve . The easiest to access , use & pricing are big decision makers . Keep us up to date on next steps . Thanks Doug S

Erling S

Monday 5th of August 2019

Greetings. You guys are providing a great resource, thanks especially for the eberspächer review. I picked up a tip from Greg Virgoe; use "Self Adhesive Insulation Stick Pins" for any rigid foam boards on (in?) ceiling.

For those that want a wood stove installed (me, when I get the money for a build), PIR is probably not a good idea because of cyanide poisoning if we burn our van down.

Nate Yarbrough

Tuesday 6th of August 2019

If you burn your van down, I recommend not staying inside the van long enough to get cyanide poisoning.

Sandro Trunz

Wednesday 31st of July 2019

Hya Explorist.Life,

Were'nt you ever worried (obviously not - so WHY were you not worried) about fumes exuding from foam sealant (Great Stuff)? Tight seals via panels / lining?

Many thanks and builder's greetings, Sandro

Nate Yarbrough

Friday 2nd of August 2019

What fumes, specifically, are you worried about?

Runa Tarannum

Wednesday 10th of July 2019

Hi Nate and Steph, Thank you for the amazing videos. I am in a process of first step of my project campervan to build out plan (material/costs and execution phases) before jumping into purchasing. I am taking this project on a single mom budget but want to build something that my 4 year old and I can use for our adventures years to come. I want to insulate this very well from get go because I want to ensure it works if we decide to do some winter adventure in future.

I am an engineer by profession and have some experience with wood-working which gave me the confidence to take this on.

Questions for you:

- How did you go about picking your insulation material? - Did you guys do the R-value for different type of terrain before picking the thermasheath? Which particular type did you end up using? - Is this process doable by one person in your opinion?

Nate Yarbrough

Thursday 11th of July 2019

For picking insulation material we just picked the one we felt would work the best and went with it.

We did not worry about R-Value. We just insulated as much as we could, where we could.

The process is doable by one person for sure.

Though, if we were doing this again; we would entertain the idea of having it spray foamed and call it good.