DIY Window Installation for Van Conversion

Last Updated: July 24, 2021

DIY Window Installation for Van Conversion


Adding an aftermarket window to a van seems like an intimidating task, but it is actually totally doable by the average DIYer. When you think about it, it is very similar to adding a roof fan… which is an -almost- obligatory rite of passage for all DIY van builders! We personally didn’t add a window to our van, but it is part of our “If we had to start over” list… Keep reading!

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1- Theory

1.1- Ventilation

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


The Maxxfan has an integrated cover that prevents rain from entering the van, making it possible to run at all times. That’s a big deal because ventilation is important during episodes of rain. We’ve been living full time in our van since 2017, and we highly recommend the Maxxfan:


The volume of air “removed” by the roof fan must be continuously 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.) These are referred as passive intakes.

A passive intake offers a lot of resistance to air flow; too small and your intake won’t be effective! 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.

Exhaust Area.
Intake Area.
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 ambient 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 pollutants can cause respiratory problems, and proper ventilation helps recycle the polluted air with fresh air. 

Non-exhaustive list of pollutants:

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 great, but help is sometimes welcomed:

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 thought!


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 intend to use 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 emphasize that enough!

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 and 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 line: If your van comes with factory rear windows, fine. But we personally think it’s not worth adding them 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 as shown on the next photo.

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


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 screws but don’t fully tighten –> Tighten all around –> Test for water leak. 

  • The cutout template is created using the trim ring.
  • 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.

On Second Thought....

We didn’t add a window to our van, but it is part of our “If we had to start over” list… During those hot summer days, a window would definitely increase ventilation, and purging hot air while driving would be neat!

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About us



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!