01Van Build Guide

Sprinter Van Insulation

Step by Step Guide to the DIY approach to building your Sprinter Van



Insulation is where people end up spending the most amount of time researching. Not only is there an endless amount of options, but it also happens to be the very first thing you’ll do to start your van build.


At this point you’re still under the impression that every decision is going to be make or break and that it might potentially ruin the entire build….

Let me start by telling you that as you get further and further along, the decisions become much, much easier…. I’d say it’s somewhere between tossing in the ceiling fan and cutting in your first window where this starts to happen.

So rather than spend a year of my life writing an article that talks about the difference between hundreds of insulation types, along with their PROS and CONS, I’m just going to talk about what insulation I used and why I selected it.

Thanks to my Espar Heater keeping an interior temperature around 16-18C, I’ve had my van in -35C and got by just fine. So even though I might not have the best insulation in the entire world, it works for me.

My van build spanned 3 different seasons, including the dead of a Canadian winter, and was all done outside of a garage. For that reason, I’m pretty confident in my process and its ability to keep the van at a manageable temperature even in the harshest of winter climates.

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Vapor Barrier is a material used for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through wall, ceiling and floor assemblies of buildings to prevent interstitial condensation and of packaging. Some people choose not to install a vaporizer barrier in their vans but since I had planned on using my van in the winter and heating the interior of the van I decided it was a wise decision to install after the insulation process on the van.

Vapor Barrier
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Reflectix is a very versatile product that's used in many van builds. It’s a great product because it inhibits condensation, no mess, mold and mildew resistant, and it’s lightweight. The biggest reason for using it in my build was because it reflects up to ~90% of radiant energy. On the Reflectix website you’ll see varying amounts of different R values promoted. Overall, I think the actual insulation value provided by the Reflectix is quite low but it's ability to reflect is the biggest reason I chose to install it in my build. The cost of the product and time to install it makes it almost negligible, so why not toss it in.

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For the bulk of my insulation, I decided to go with Polyiso Insulation with a foil backing. Polyisocyanurate (polyiso) is a closed-cell, rigid foam board insulation consisting of a foam core sandwiched between two facers, usually a metallic foil. The reason I chose to use Polyiso for my build was that it was very easy to work with and it has the highest R-Value per inch. For a long time I had debated using a spray foam application on the build but after reading so many horror stories of people who wrongfully applied the material and damaged the outside sheet metal of their van, I was scared away. I think both Polyiso and Sprayfoam are good options, but I just wasn’t willing to take the risk at ruining a new van. Since I wanted a material that I could handle myself, Polyiso was the obvious winner for me.

PolyIso Insulation
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It’s nearly impossible to get the rigid insulation to fit perfectly in some areas of the van. In the areas where I need to be able to stuff the insulation in the various nooks I chose to use Roxul Batt Insulation. It was inexpensive and really easy to work with.

Roxul Insulation
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There were a few areas where I couldn’t get in when using the Roxul insulation. To block those areas, I used cans of spray foam…. I'll be the first to admit that this was a very slow process. At this stage of the build I felt like I was in a bit of a rush, thinking I would be done in 2 months… So if I could go back to the van build I would have taken more time to completely fill all of the cavities that I couldn’t get insulation in. With that being said, I’ve had the van in -35c with an Espar heater and I can get the interior to 18-20c.

Spray Foam
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When researching your van build, you’ll find that almost everyone uses some sort of sound deadening material. The most common are rattle trap and Dyna Matt. Although I do think that a sound deadener of some sort is a great idea, I didn’t use either of these materials. Instead I decided to use Resisto Peel and Stick which is a foundation waterproofing material you can find at Home Depot. This material was a fraction of the cost and seemed to do a fairly good job at getting rid of the tinny echo in the van.

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Foil tape was used on the floor of the van once I laid the sheets of Polyiso board to seal off the seams. I probably could have used any construction tape here, but I went with the Metal Foil tape because I was using foil backed insulation.Overall lifespan of foil tape is far greater than most other alternatives that could have been used. Also, foil tapes are known for having extreme temperature versatility which makes it a great option for a product being used in an all season conversion.

Foil Tape
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Tuck Tape is made of UV resistant poly propylene film and is coated with high shear, high tack solvent based acrylic adhesive. Applications include sealing of joints and seams of house wrap, insulation materials and foam underlayments for laminate flooring. While I was hanging the Polyiso insulation on the walls, I found it super handy for holding on the insulation while I waited for spray adhesive to dry.

Tuck Tape
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