• Becca and Cade

Building a Sprinter Van Conversion: Ventilation, Insulation, & Walls

Note: this post is about our first Sprinter Van, which we bought in May 2016, converted, lived/travelled in, and sold May 2018. If you are looking for info about our second Sprinter/current project, please check the dates of the post and make sure you're reading posts from 2018/2019. Cheers!

After gutting the interior of your new Sprinter Van, the next steps to consider are ventilation; soundproofing; insulation; and paneling the walls/ceiling, and flooring. We'll discuss a few options, and the choices we made regarding each of these important aspects of the buildout of your new van.

Sprinter Van Buildout: Insulation

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Choosing an Overhead Fan

We found 2 main choices for non A/C roof vents: the Maxxfan and Fan-tastic fans. They both come in multiple models with features like power or manual opening, multiple speed settings, 2 different modes so it can be used like a ceiling fan or an exhaust fan, auto rain sensing, thermostat control so you can set it to come on automatically when the inside temp gets too hot, and remote control so you can turn it off without reaching above your head. We ended up going with this Maxxfan mostly because the vent can stay open with the fan running in the rain. The vent hood is also a bit lower-profile on the roof. This originally wasn’t something we were paying attention to, but after carrying our Tower Paddleboards on the roof rack a few times, it turned out to be really advantageous.

Fan Positioning

There are 2 mounting options for roof vents on the Sprinter where a 14” by 14” hole will avoid going over any ribs. This is important so it makes a clean seal and you don't get leaks down the road. One option is near the back of the van and the other sits behind the front seats. There are pros and cons for each. In our layout the aft position would put it over our bed which would be good for nights with high temps when a little bit of airflow over the bed is needed and adjustment without getting out of the bed is ideal, but it would be hard to access from the kitchen.

We decided on the forward position to put it closer to the stove. Ventilation while cooking was our priority. Some people put fans in both spots, but we wanted the extra roof space for our solar panel in the back. We also don’t spend a ton of time in hot climates--we primarily travel in the mountains, where cool nights are the norm. One other thing to keep in mind is road noise. The vent can be noise at freeway speed; ours whistles a bit if we get a stiff crosswind. The rear positioning of the fan may reduce the noise you hear from the front seats. We’re working on some sort of foam sound dampener to put over ours while we’re driving--we’ll keep you updated.

Fan Installation

With the position chosen it was time to cut into the roof. We measured about 16 times to make sure we had the size and placement exactly right and marked the lines with tape. We then started by drilling the 4 corners on the hole from inside the van, then used a jigsaw from the roof to connect the corners with straight lines. After cutting, we cleaned up the edges with a file and primed the bare metal with automotive primer. We made a square wooden frame out of 2x2s to screw the Maxxfan to through the ceiling. We then placed butyl tape between the flange of the fan and the metal of the roof and screwed through to the wooden frame. We covered all the screw heads as well as the rim of the entire unit with dicor sealant on the roof to prevent future leaks.

Hole for Solar Panel Wires

One other major consideration at this stage is making another hole for the cables that run from the solar panel to the interior of the van. For the pass-through of these wires, we used a hole saw to drill another hole just big enough to get the connectors through. We did this directly under the solar panel, so it would be partially protected from precipitation. We then put a big rubber grommet in the hole and again covered the whole thing with the self leveling sealant. It should be noted that in order to pass these cables through the hole, our solar panel actually needed to be installed on the roof already. For clarity we’re going to save info about the solar panel for a future post about the electrical system, but just know that realistically you would already have your solar panel installed at this stage.

Sound Dampening

There are a few aspects to sound damping a vehicle. First, you want to reduce vibration in the metal body panels, especially the bigger ones. This is done by using constrained-layer damping (CLD) tiles. There are some of these already installed from the factory. You’ll see them once you strip the interior, although they are painted over, so partially disguised. There are a number of different products for this. Lots of them using asphalt, tar and other toxic petroleum distillates. We ended up using Fatmat Rattletrap, which uses a slightly less toxic butyl rubber compound. It is fairly easy to apply. It is foil backed, and you can cut it with a utility knife. We heated it up with a hair dryer and used the included roller to stick it on and smooth it out. We placed tiles on all of the large metal panels that were lacking the factory-installed sound dampener. We had also read that a large amount of road noise comes from the wheel wells, so we covered them completely.

Another option is to add mass loaded vinyl or closed cell foam to the entire panel, but this can get expensive in a hurry. We did not worry too much about it. On top of this, you want to have a sound absorbent material, which is usually your insulation. And lastly you want to “decouple” the exterior from the interior. This is easier said than done for a vehicle, but we did our best by having the outer wall separated from the inner paneling wherever possible.

Rough Wiring

The next step is to run rough wire for the lights, outlets, and other electrical components throughout the van. We will go into more specifics later in a post about the electrical system, but it’s necessary to do this before you insulate and install the walls and ceiling. For the wire runs, we cut a 25-foot heavy duty extension cord into pieces (thanks for the idea, Roaming Robos) for all the 110v outlets. This made an easy weatherproof and wear resistant medium instead of running a positive, negative, and ground for each outlet. For the lights, fan, 12v outlets, and water pump, we ran 14 and 16 gauge automotive wire. For connecting our batteries together and to the charge relay we used 2 AWG welding cable.

Note: Once you’re finished running the rough wires, label each one very quickly with durable tape and permanent marker or something similar. Take lots of pictures of the walls and ceiling where all the wires pass through. Later when you’re drilling into the walls to attach cabinets and hang things, you will know the spots to avoid. You'll also remember which wires are which from all your handy notes. It would be a shame to mess up all that hard work. In addition, there is one thing we would change from our build. Somebody suggested using conduit to do all the wiring runs before we started building and we foolishly decided against it. If we were going to start over, we would absolutely use conduit. It would make pulling new wires through and making changes down the road a breeze. More details in the post about our electrical system.


With all the wiring in place, it was time to insulate. Most people also use some combination of layers of Reflectix in their insulation process. It looks kind of like silver bubble wrap and there is mixed information on whether it actually does much for vehicle insulation. It is a radiant barrier so works great for things like putting shades in your windows and reflecting the sun on a hot day but whether it is an effective insulator inside the walls is harder to get a straight answer on. There are people all over the internet arguing both sides. In the end we figured it probably wouldn’t hurt, and might help a little. We bought 48” wide rolls and cut pieces for every exposed piece of metal panel on the interior of the van.

Many people use 3m Spray Adhesive to stick the Reflectix to the metal and the insulation to the Reflectix. Wherever possible we avoided this, again to cut down on the toxic fume factor. You can tie most of it on to the metal ribs on the van (or hold it up with strings across the panels from one rib to another, which actually turned out to be way more effective than the adhesive as well. The other option is foil tape. We did end up using quite a bit of Reflectix, as we used it to make shades for the windows as well--this is a must-do for any Sprinter owner (more in a later post).


There are lots of different choices here and we spent a lot of time weighing the options:

  1. Fiberglass batts, like in most homes

  2. Foam: either closed or open cell, foam board or spray foam

  3. Thinsulate

  4. Recycled Denim

  5. Wool: either loose or batts

We ruled out fiberglass right away. It tends to settle with vibration, doesn’t handle moisture well, and is super itchy/toxic to work with. There are lots of options for foam--this is probably the most common type of insulation that others have used in their builds. Foam board is the easiest to work with and comes in different r-values. Spray foam is perhaps the most effective form of insulation and can get in all the nooks and crannies, but is permanent and can be tricky to apply with big consequences if you mess it up. We saw some pretty unfortunate pictures of people who had warped the body panels of their beloved vans by improperly applying the spray foam. Foam can also release harmful fumes long after installation, and although some types are better than others, we were looking for our van to be as non-toxic as possible.

So we were down to denim and wool for our natural options. Although the denim insulation is treated for mold resistance, we felt more comfortable with wool handling condensation issues. The wool option also has a higher R value. We had some help from the guys at Eco-Building Products. Although they had no experience with anyone using their Black Mountain Wool Insulation for a van, they helped us make a decision after a few conversations. If we hadn't gone with wool, we might have chosen denim or Thinsulate. Although Thinsulate is synthetic, it is fairly low on the toxicity scale, but doesn't have a great R-value.

Some of the factors that played a role in our choice:


  1. Wool controls condensation, absorbing and releasing moisture without losing thermal performance

  2. It absorbs fumes. Foams emit toxic gases.

  3. Sustainability: it requires very little energy to manufacture (up to 85 percent less energy compared to man-made products)

  4. Wool is biodegradable at the end of its life

  5. It is safe to handle, no skin or respiratory problems typical of other types of insulation

  6. It has a great R-Value


  1. Wool insulation takes a little while to get, as it’s not generally available locally. By the time we had made a decision, we were pretty much ready to insulate. We ended up having to wait a few days for delivery, which can be frustrating at this critical step. If you plan ahead better than we did it shouldn't be an issue.

  2. It’s more expensive than the other options.

  3. The type we used is imported. As far as we know, there are currently no suppliers of American-grown wool in batts. You can get loose wool insulation from a few US sources, but then you would have to figure out how to install it. *2018 update: it seems wool batts are catching on and there may be more local options becoming available. We are researching this option for our next van and will update once we know more.

  4. It’s a bit of treading on uncharted waters. We have had ours for 6 months and couldn’t be happier, although this isn’t much of an objective opinion as we don’t have anything to compare to. Because it hasn’t been used in vans much, we don’t really know how it will hold up over the years.

We ordered more wool than we needed. Our estimates were actually pretty accurate, but we realized after our order arrived that the bats come in two layers. The bats can be easily separated and double the surface covered (while decreasing the R-value). We left certain sections double-layered, but there were many places that it just made more sense to use the thinner sections. If we were doing it over again, we would order two 16" rolls and one 24" roll. This does not include the area above the front seats--we left the headliner intact here and just stuffed excess pieces back in the holes. Becca came up with a pretty good system of stuffing the smaller sections with appropriately-sized pieces of insulation, which held itself in place just with friction. The larger sections were a bit more challenging, but she hung them with re-used paragliding line (basically just strong nylon string) woven through the mesh on the insulation tied to the metal ribs of the van. It took a little help from Cade’s family, and a lot of hands (and maybe one spatula) to hold/stuff all the layers in place as we placed each wall and ceiling panel, but overall the installation was super straightforward and totally non-toxic. We are totally happy with our choice to use wool.

Walls and Ceiling

There are lots of options for paneling, starting with whatever stock materials were already in the van. We have seen some very good looking builds using all sorts of wood on the walls: from flooring to cedar planks, barnwood and everything in between. RB Components makes pre-cut wall and ceiling kits for all lengths of the Sprinter, we have not seen it in action, but this would be by far the easiest way to finish your walls. We decided to go the hard route and make our own. We knew we wanted to cover our walls with topographical map wallpaper, so we just needed a lightweight, durable medium to apply it to. We ended up using some ⅛” underlayment on the ceiling and ¼” birch ply on the walls, both of which we got from Home Depot. Certain Home Depot stores (and other hardware stores) carry FSC certified wood. We used FSC lumber whenever possible. It's worth checking in with your local stores to see if it's available in your area. The more of a market we create for these products, the more stores will strive to fulfill that demand.

As we started to cut our plywood for the ceiling and walls, we truly understood for the first time that there are very few (if any?) straight lines in the van. We had read this statement over and over again in all the blogs we had been studying, but it doesn’t really sink in until you’ve experienced it for yourself. This fact will continue to haunt you through every part of the build. We had to scribe corners and curves into every piece of ply as we cut out the wall and ceiling panels, but fortunately thin plywood is cheap, easy, and flexible. It turned out to be the perfect place to get some practice, as we were definitely going to need it for the rest of the conversion process. We’ll take this opportunity to also remind you to measure 4 times and cut once. We only had to go back to the hardware store for a replacement sheet one time-- whoops. For our purposes, we decided to cover the upper walls only, and keep the factory paneling down low. In the back, the lower section is all storage area under the bed, and up front the panel is hidden behind the kitchen cabinet. On the lower section of the sliding door, we left the factory panel as well, but may change it out for more maps in the future. We attached all of the wall and ceiling panels (and pretty much everything else in the van) to the metal ribs in the van with pan head/ flat head self-tapping sheet metal screws--length may depend on the thickness of the material you are attaching.


We looked at lots of options for the floor. Many people add more Rattletrap or another CLD for soundproofing, especially if you are putting your finished floor right on top of the metal. Some people also insulate by adding reflectix or foam, either just in the spaces between the ribs of the floor in long strips, or for more extreme weather protection they will add one more layer on top of that before putting flooring down. We decided not to worry about insulation in the floor too much and to keep our factory floor for a few reasons: it has tie downs for the storage area in the back, it has a foam bottom layer and attaches with velcro to reduce rattles, and it would make a good flat subfloor up front for attaching whatever type of finished floor we decided on. We’ll discuss more on the finish flooring we chose in a future post.

If you find this blog post helpful, please feel free to visit our Thank You page to leave us a note or send us a Paypal contribution that will allow us to continue producing useful content. You can also use the Amazon affiliate links throughout our posts to help us earn commissions on your purchases. You pay the same price, we earn a small fee. Thanks for helping us help you!


Fan: Maxxfan

Soundproofing: Fatmat Rattletrap

Insulation: Reflectix and Black Mountain Wool Insulation





automotive primer

butyl tape

dicor self leveling sealant

hole saw

utility knife


25-foot heavy duty extension cord

FSC certified plywood

Self Tapping sheet metal screws

Gear We love

Tower Paddleboards

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#VanBuilding #VanConversion #VanLife #VanLiving #SprinterVan #Planning #Ventilation #Insulation #WallsandCeiling #Materials

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