DIY Window Installation for Van Conversion


DIY Window Installation for Van Conversion

Adding aftermarket window(s) to a Transit, Sprinter or ProMaster van conversion has many benefits and is totally doable by the average DIYer. Let’s dig deeper!

Table Of Content

Our Favorite Tires
Ford Transit, Mercedes Sprinter, Ram ProMaster

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1- Theory

1.1- Ventilation

First obvious role of a window is ventilation. A proper ventilation system normally have an exhaust and one/several intake(s):



The Maxxfan has an integrated cover that prevent rain from entering the van, even when the fan is running. On the other hand, the Fantastic is basically like a big hole-in-the-roof: its cover must be closed when raining. To compensate, the Fantastic has a sensor and will automatically close when it detects water. But it’s when it rains that controlling moisture and condensation is critical! From our experience, not being able to ventilate when it rains doesn’t make sense. For this reason, we highly recommend the Maxxfan.



The volume of air “removed” by the roof fan must be replaced by the same volume of fresh air, otherwise the ventilation system doesn’t work. In most cases, there is no fan to push the air inside: as the exhaust fan creates a negative pressure inside the van, air is “sucked” into the van by any intake available (windows, holes, cracks, etc.) This is referred as passive intakes.

Keep in mind that a passive intake offers resistance to air flow; too small and your intake won’t be effective (so your ventilation system)! Try it: close all intakes (windows, holes ,etc.) and you will hear the roof fan “force” as it cannot pull air outside.

Think of surface area: ideally the intake should have a similar area as the exhaust. For example, the Maxxfan exhaust is 12in diameter; that’s 113in2 surface area. It’s quite large, so a window is ideal as a passive intake. In comparison, a hole of 4″ diameter has 12.5in2 and a 4″ square has 16in2 

Adding a window helps controlling:

Thermal comfort for a person at rest is around 72±4F (22±2°C). While an air conditioning unit can be used to control ambiant temperature under extreme heat (actually, unless you have a generator or you are plugged to shore, it’s not too realistic for off-the-grid applications), ventilation can do it too under normal conditions for a fraction of the energy bill.

Indoor Air Quality

Indoor polluants can cause respiratory problems and proper ventilation help recycle the polluted air with fresh air. 

Non-exhaustive list of polluants:

  • Cooking Odors and Fumes
  • Carbon Monoxide
  • Other's Farts
  • Burning Candle (yep! Google it!)
Relative Humidity

Thermal comfort depends on temperature, but on relative humidity as well: the ideal range is 50±20%. We have a pretty solid article about controlling moisture and condensation, we think you’ll like it:

Condensation And Moisture In A Van | Why It Happens And How To Control It
Air Movement

Humans are more comfortable when air is not stagnant. A window works, but help is sometimes mandatory:


Sirocco 3-Axis 12 Volt Fan Review

1.2- See The Outside World

Of course!

B-U-T! There are a few things to keep in mind:


Small spaces are fast to clean, but they get messy in a blink of an eye. Trust us! When living in a van, the key to sanity is organization. Having multiple storage options all over the van is important, so that each thing has its own dedicated place and can be easily put back to where it belongs.

Windows reduce storage potential; it’s a trade-off. That being said, we could add windows without removing storage in our layout… Food for thoughts!

10 Neat Storage Ideas for DIY Van Conversion

Windows are the weakest link for heat loss. Each additional window reduces your insulation capacity and is an opportunity for a cold draft. So if you intent on using your van as a ski hut like us (, think twice before adding windows all around.

Finally, adding insulated window covers are a must to keep the van comfortable; it makes a HUGE difference, we can’t emphasis on that enough!

DIY Insulated Window Covers
Rear Door Windows

Number of times we removed the insulated window covers ( from the rear door windows to look outside: ZERO.

And this seems to be a consensus among people that have a layout similar to ours (garage and raised bed). It’s romantic to think we wake up and look outside and stay in bed and all, but that just doesn’t happen in real life. If we want to see outside, we grab a coffee then go outside. In winter we get out of bed, grab a coffee and hang out by the “fireplace” (a.k.a. the Webasto while looking through the sliding door window.

Bottom Word: If your van comes with factory rear windows, fine. But we personally think it’s not worth adding some if you have a garage + raised bed layout.

1.3- Window Location

Most folks position their roof fan towards the rear of the van. We personally cook (stove/oven) a lot inside the van during winter, so we positioned our roof fan towards the front of our van, near the kitchen range (


Ideally, you want your exhaust (roof fan) and you main intake (window) far apart from each others. The goal here is to create a draft that travels through the van’s length to optimize circulation and ensure air is recycled at every corners.

1.4- On Second Thought

Wait, what? Our “Second Thought” normally comes at the END of the article! Here’s what’s going on:

We did NOT add a window above our bed and, well, maybe we should have. The floor vent ( works OK, but it’s not good enough as passive intake; the in-line fan must run and is pretty noisy (note: it’s great as stealth ventilation in cities when we’re out of the van). Also, a window would be much more efficient at purging big volume of air (i.e. when driving). 

We plan on adding a window during summer 2019 (Half-Slider Bunk on passenger side), so what comes next is planning rather than build documentation… we will update this article when the window will be added!

2- Window Options

CR Laurence (CRL) is without a doubt the most popular window option. Except for the half-slider, their design is “all-glass” so it looks very OEM. They also come with a detachable mosquito screen. We’ll go with CRL for sure!


3- Window Installation

We plan on installing a half-slider bunk window during summer 2019, so here is the planning:

Make the cutout –> Primer/Paint –> Install window from outside –> Install trim ring from inside –> Pilot screw locations –> Install all crews not fully tighten –> Tighten all around –> Test for water leak. 

  • The cutout template is created using the trim ring.
  • We will consider using an electric metal cutter shear (Buy on Amazon) as it produces less debris than a jigsaw. (don’t think it can go through frames though)
  • As usual, exposed edges (after cutting) must be painted to prevent corrosion.
  • CRL Windows are clamped to the body of the van using a trim ring and a weather seal; no sealant is needed. 
  • It is recommended to pilot (make tiny holes) at each screw location.
  • When clamping the window, a manual screwdriver should be used to prevent distortion of the trim ring.


Let us know if you have some recommendations before we do this!


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about us

Nice To Meet You.

Hello! We’re Isabelle and Antoine 🙂 In 2017 we sold our house (and everything in it), quit our engineering careers and moved into our self built campervan. We’ve been on the road since then and every day is an opportunity for a new adventure; we’re chasing our dreams and hopefully it inspires others to do the same!

7 thoughts on “DIY Window Installation for Van Conversion”

  1. Hi guys,

    Our experience mirrors that of others. We put a half bulk window in the rear passenger side. Saber saw worked well, and by sawing at an angle, we also took out the majority of the offending reenforcement metal that interferes with the interior trim of the window.

    In terms of ventilation, worked great. We were in California in August, and the temp in the bed area at night was what ever the outside temp was. We sleep transverse, so the window breeze was coming in right in our faces, nice.

    Anyway, one problem was figuring out a window _still_ (or _stool_ is actually the correct name I think). It was a challenge, but very important. The window is water tight EXCEPT when we leave it open. (Duh.) We left for our first trip before doing anything. We would go out for a ride, leaving the window open for ventilation, and come back with water in the van after a thunderstorm. This was because the water went thru the screen, into the van wall and came out at the bolts for the bed supports. Very bad. Later, when I took apart the wall to see what was going on, the wood at the bed supports was already molding and that was only three months after the installation. (!)

    Our solution was to use oak corner guards (google: evertrue lowes oak corner guard 1″ x 8′ x 1″). Because we sleep transverse, a 3′ by 2′ portion of the wall is quite thin where our heads (and feet on the drivers side) are, only insulated with 1/2″ foam plus 1/4″ mini cell. So, the corner guard is the stool, and all cracks were carefully sealed with silicone. Now, when it rains, it goes into a towel that we strategically leave on the bed, no problem. Even if the bed or pillow should get a little wet, it quickly drys, no problem.

    One other problem is, when sleeping at -11C, those windows ice up, and good luck opening them. Maybe another window cover? We haven’t figured this one out yet.

    Anyway, the half bulk window is great, highly recommended.

    Cheers, Don

  2. We installed and are happy with them. Way easier to install than bonded windows (we screwed those up and had to take to a shop to fix, ha). Framing them out was time consuming but not bad. Used a lot of VHB tape.

  3. Just curious – why not go with awning-style windows like those built by Tern Overland? We’ve had awning windows on all 3 of our various camping trailers (2 Airstreams and a T@B) and love being able to open them in the rain.

    They lack the flush and sleek look of the CR Lawrence windows tho…

  4. Just installed a CRL half bunk window on our 2018 Transit High Roof about a week ago. Was definitely easier than expected, although I still haven’t wrapped my head around a wood frame for it. I may back out the interior trim and add in a frame between the window bits.

    I followed the same installation steps as my roof vent, and made sure to position the window as high as it could on the wall to accommodate the bed / matresss. Even crammed up to the top, the mattress will likely be overlapping the window slightly.

    Jigsaw worked great, then filed down any rough bits. Used a dremmel to trim any wall supports that were in the way of the interior trim, but still, the jigsaw cut right through all of that!

    • Hey Miles,
      I’m working on installing my CRL bunk window but came to a sticking point with those wall supports, realizing that the window wouldn’t sit flush with them. You got past this by just dremmeling them away? Any advice for people without a dremmel? Or just window install advice in general?

  5. I put side back windows in my ’69 Econoline, they were great. Sort of weird these days, they had a crank that opened the windows outwards, so you had two little glass winglets on each side (but I never got much lift). They had screens. Those were the days before pop-tops had fans, but the passive convection at night was enuf to bring cool air in to breathe. You’re doing the right thing.

    We ordered no windows in the back, but we will be adding them to make the van less cave like.


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