So this is what I did first...

Ok so this is where most people choose to begin their van conversion and probably spend the most amount of time researching. I think part of this problem is that not only is there an endless amount of insulation options but it also happens to be the very first thing you are completing on your van. So at this point you are 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 and much easier…. I think its 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 the hundreds of kinds of insulations and pros and cons associated with each Im just going to talk about what insulation I used and why I selected it. FYI I’ve had my van in -35C and been fine with the Espar heater keeping an interior temperature around 16-18C. So even though I might not have the best insulation in the entire world….. it works for me. My entire build was done outside, no garage and spanned 3 season into the dead of winter in the middle of Canada so Im pretty confident in my process and its ability to keep the van at a manageable temperature even in the harshest of winter climates.

DifficultyBeginner Duration2 Days

Materials Used

Reflectix is a very versatile product that is used in many van builds it is a great product because it inhibits condensation, no mess, mold and mildew resistant, lightweight, and the biggest reason for using it in my build was because it reflects up to ~90% of radiant energy. On the Reflectix website you see see varying amounts of different R values promoted. Overall I think the actual insulation value provided by the Reflectix is quite low but its ability to reflect is the biggest reason I chose to install it on my build and the cost of the product and time to install make it almost negligible so why not toss it in.
Iso Foil Insulation 3/4 (3 of them) and 1 inch (4 pieces of them)

For the bulk of my insulation I decided to go with Poly Iso 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 debated using a spray foam application on the build but after doing a lot of reading I got scared away after reading horror stories of people who wrongfully applied the material and damaged the outside sheet metal of their van. I think both Polyiso and Sprayfoam are good options but I just wasn’t willing to take the risk at ruining a new van and since I wanted a material that I could handle myself that made Polyiso the obvious winner for me.
Some areas of the van it’s nearly impossible to get the rigid insulation to fit perfectly for these areas where I need to be able to stuff the insulation in the various nooks I chose to use Roxul Batt Insulation. It was in expensive and really easy to work with.
Then a few areas where I couldn’t get in the Roxul insulation I used the cans of spray foam to block up these areas…. Ill be the first to admit that this was a very slow process and at this stage of the build I was in a bit of a rush thinking I would be done in 2 months… So if I were to go back to the van over I would have taken more time to completely fill all of the cavities that I couldn’t get insulation in. But this being said I have had the van in -35c and with the Espar can get the interior to 18-20c so it still works just fine.
When researching your van you will find that almost every discusses uses some sort of sound deadening material. The most common are rattle trap and I think Dyna Matt and although I do think that a sound deadener of some sort if a great idea I didn’t use either of these materials. Instead I decided to use Resisto Peel and Stick which 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.
Foil tape was used on the floor of the van once I laid the sheets of Poly Iso 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 and 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 temperate versatility which makes it a great option for a product being used in an all season conversion.
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 housewrap, insulation materials and foam underlayments for laminate flooring. I found it super handy for holding on the insulation while I waited for spray adhesive to dry while I was hanging the PolyIso insulation on the walls.
Vapor Barrier is any 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 to not install a vaporizer barrier in their vans but since I 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.

Tools Required

Install Process


The first step for me was to Install the sound deadening material. For this I used Resisto which is actually a peel and stick waterproof membrane for home foundations, it was considerably cheaper to use this than the proper materials and it seems to the trick is reducing the tiny sound created by all the large metal panelling in the rear of the van. When installing the resisto on the sides and the ceiling of the van I just cut rough squares to size and stuck them in place. The idea behind this type of product is to just remove some of the vibration that is caused therefore reducing the amount of noise while driving the vehicle around, when installing you can tell the difference just my using your knuckle and knocking on the side of the van before and after installing the product.

After Installing the sound deadening material on the walls and ceiling the next step was to install the reflectix. On my build I used reflectix on the ceiling in between the ribs of the van, to install the reflectix I just used some 3M spray adhesive and spraying both the area I was placing the material and the back of the reflectix before tacking it in place. The actual insulation value of the reflectix I think is fairly minimal but the install is quite easy and is supposed to add an additional radiant barrier to help stop the suns heat from penetrating into the vehicle.

I also decided to play the reflectix in the large middle areas of the van where the windows would be placed on the passenger version of the sprint van and overtop of the wheel wells on both sides of the vehicle to assist with road noise.

Once I had completed the reflectix install It was time to install the PolyIso Insulation. The polyiso was used in the larger symmetrical areas of the van where minimal cutting and fitting was required such as the ceiling, floor and large middle areas on the sides of the van.

Cutting the polyiso is easily done with a utility knife and straight edge making this stage fairly quick and easy to manage by yourself. To install these large sheets I used a combination of spray adhesive and tuck tape to hold the pieces in place until my wall panels were installed. On the ceiling I was able to cut the section to tight enough to just friction fit the pieces in place which made installing the ceiling sections probably one the fastest and funnest parts of the insulation phase.

When you get inside your sprinter van you will quickly notice how many different nooks and crannies there are in the bottom and top sections of the van making using the polyiso insulation a rather time consuming task. So instead of using the poly iso in these section I opted to use roxul batt insulation which was super easy to work with and made it possible to jam into all the hard to reach places on the van including inside all of the door cavities.

The last bit of insulation on the walls and ceiling that I had to complete was the channels that are located in the ceiling ribs and right below the areas where the windows are located if you have the passenger version of the vehicle. For these sections the access holes are quite small making it nearly impossible to stick in the roxul insulation, so my only option was to get some cans of expanding spray foam to insulate these areas.

Now that 95% of the insulation was completed I could go ahead and install the vapour barrier over the insulation in the van. The vapour barrier is super easy to install…..if you have two people. I tried to do this on own but the size of the sheets makes it awkward and difficult to manage by yourself. For my install I cut the pieces to rough size and then tapped one edge in place using tuck tape, then I sprayed the plastic with spray adhesive and the insulation as well then tacked it in place. The spray adhesive did an excellent job at holding at the vapour barrier in place making it so I didn’t have to worry about it falling down or using tape everywhere to hold it in place.

Floor Insulation

For the insulation on the floor its more or less the same application except I didn’t use any of the spray foam or roxul insulation. I know a lot of people that have recently done van conversion chose to only insulate the walls and ceiling and not to bother with the floor. I know for me personally Im so glad that I took the extra half day to insulate the floor because even though I am able to get the van to around 20c in the winter with the spar heater the floor still remains cold and I need to wear slippers while walking around so I couldn’t imagine the amount of heat loss I would get if I didn’t take the time t quickly insulate the floor of the van.

On the floor the first step for me was to install the same resisto peel and stick membrane that I used on the walls and ceiling as a sound deadener on the entire floor of the van. The resisto on the floor acts not only as a sound deadener but it also waterproofs the entire floor or the van since that was actually what this product’s intended use it.

After I installed the resisto over the entire floor of the vehicle I needed to put some wooden strips in the ribs of the floor on the van. For this I just quickly cut some plywood pieces about 2 inches wide by 2-3ft long and secured them in place with a little bit of construction adhesive made my PL. By taking the time to level out the floor it ensured that when it came time to install my flooring I was working with as flat and level a surface as possible in the van.

Once I had filled in the low points between the ribs in the back of the van I began to lay out the polyiso insulation. For the flooring I decided to use 3/4 thick insulation in order to just maximize the head space  that remained in the van once completed. After I had cut and dryfit all of the insulation I pulled it up and placed construction adhesive all over the floor and then stuck the insulation back down to the floor. Since the insulation I used was a foil backed polyiso I decided to tape the few seams I had on the floor with a foil tape, my thought process here was that if moisture did find a way to get to the insulation it wouldn’t be able to seep through the seams between the insulation panels.

Now that the insulation was complete on the floor it was time to install a sub floor in the van. Since my van was brand new it came with a nice 1/4 thick plywood floor that was already cut and ready to fit the van, so I just reinstalled this over the polyiso insulation. Due to the fact that I had built up the floor on the 3/4 of an inch with insulation the factory fastening system for the floor would no longer work so what I did was a forester drill bit to counter sink self tapping screws through the plywood and into the metal floor of the van. One thing to note in using this method of fastening the subfloor to the van is that you are left with multiple screw penetrating the underside of the vehicle that will rust over time, so in order to eliminate that I used a automotive sealant for installing windshields and covered all of the exposed screw on the underside of the vehicle in stop them from rusting over time. The product I used looks very similar to a roofing tar and when it dries on the screw under the van it reamains pliable and soft to the touch, so it won’t dry out, get hard and just fall off.

For the flooring on the van I decided to use a vinyl laminate flooring, the reasons I went with the vinyl laminate was because its super thin and also moisture resistant. When installed the flooring its pretty straight forward you just need to make sure that you take your time and get all your seams nice and tight together. With the flooring that I used once the sticky sections of two flooring pieces touched each other there was no chance at ever getting them apart so take your time and it will turn out awesome.

Pro Tips

    • When insulating the sliding door and rear doors on the van be careful that the insulation doesn’t interfere with the internal door mechanism
    • When I first started researching the van build I had thought that I wanted to use spray foam, but after reading a few stories of people that’d used spray foam and had it warp the outer panels of the van I chose to go an alternate route. So if you are going to use spray foam be careful and its probably a wise decision to have a professional handle that for you.
    • I was pretty eager to get started once I had purchased the van and the easiest thing for me to start was the insulation. Looking back now and knowing what I know I would have planned out my electrical prior to insulating and ran some of the wires before hand.
    • I would suggest leaving the flooring install to one of the last things you complete on the van for a few reasons. The primary reason is that you won’t risk damaging the floor during the contstruction process, but also you will need half as much flooring if you only install the flooring where it can actually be seen.
    • Another note on the flooring is that when using a vinyl laminate its advised to leave a bit of a gap around the perimeter so the floor can expand and contract without causing issues. My floor currently in direct sunlight will bubble due to the expansion and Ill be fixing this shortly.