Van Build Diary 3.3: The Trickiest – Installing Universal Windows that Don’t Fit Factory Cut-Outs

Updated: Mar 15

The 3rd and last of window installations as promised! After this I can move on to the attic box, and the whole electrical system, as well as other neglected areas of the blog! Hit the subscribe button above if you want to be alerted to new posts.

So, here it is AND here is the simpler, less stressful, less likely to make a mistake installation process for windows that don’t fit the factory cut-outs, whether universal, bunk, or whatever other kind of window. We’re not sure why but there is a way more complicated install process out there that runs too many risks of messing up, especially for beginners.

There are three posts in total in this series and we went from easiest to trickiest installation ‘cause that’s what you do when you’re a beginner:

3.1: The Easiest – C.R. Lawrence Sliding Door Window

3.2: Rear Door Windows – The Leak, How Not To, & How to Fix. . .

3.3: The Trickiest – Installing Universal Windows that Don’t Fit the Factory Cut-Outs (The one you’re reading now!)

If you want more information on how we decided where to place our windows, how many windows, factors to consider like loss of insulation, type of window, etc., that was all explained in a previous post:

I highly recommend reviewing that post if you’re still deciding on placement. Your layout will determine the size of the windows, too. So, give that post a good look through to help you ponder all the variables!

In this series, we will primarily be going through the installation process, which is different for all three types of windows that we got. We started with the C.R. Lawrence sliding door window because it was the easiest. We then moved on to the rear cargo door windows, which added the complexity of having to glue the windows on (we failed and fixed it, so check it out here!)

We left these installs for last because of having to figure out the best placement given the interior framing and the competing ways of dealing with it.

So, without any further ado, we’ll jump into this LAST installation process and how we got around some really complicating cutting others opt to do that we didn’t have to.

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We placed our windows so that we could do the cut just like we would otherwise do if we were using standard Sprinter windows. Let me explain. . .

The window area looks like this:

an image of the window area from the inside. Two white arrows point to the two areas where there are two metal layers in the frame. A red outline shows an incorrect cut while a green outline shows a correct cut.
The red outline DOESN'T work; the green outline works

...and you can see there is a double-metal frame reinforcement that runs vertically in the middle of the window frame area. When you’re cutting the factory cut-out, you cut along the whole frame so that there is a double layer of metal and the rubber gasket will seal properly everywhere because it is pressed in just as tightly everywhere.

Depending on the placement of your window, you may run into a scenario where you only have one layer of metal on one side and two layers of metal on the other. This won’t work because the rubber gasket won’t seal properly on the single layer side (the red outline above).

So, you need to find placement where you can get your window onto a single layer of metal all around, which requires your window to be placed on the horizontal axis somewhere near the green outline above (you can vary it slightly so long as both vertical edges of the window reach a single layer AND you can vary its placement on the vertical axis so long as you're not right at the top or right at the bottom).

Then, you need to deal with the fact that you've got a double layer at the top and bottom of your window cutout. Let me explain further. . .

There are two ways to do this – one being a bit more complicated than the other. Needless to say, we opted for the least complicated one.

To get the complicated one out of the way, this is what you would do – you’ll cut your outline with a jigsaw. Then in the areas where there are two layers of metal, you’ll take a different kind of saw and VERY CAREFULLY cut the inside of the double-metal layer the extra width you need to fit your window in so that it only touches one layer of metal all around. When I say “very carefully,” I mean “VERY CAREFULLY.” There is about 1/8” of space between the two layers of metal and if you cut too much, you’ll cut into the outside layer of metal, making your window opening too big! I don’t even want to think about how you’d have to fix that!

Surprisingly, quite a few people choose to do it that way – we didn’t.

Instead, we made sure to place our windows so that the vertical edges were on single layers of metal and the horizontal edges cut through both double-metal layers, like so (I'll get into the details later):

The interior view of the window area with a pencil outline of the window cutout so that the window's vertical edges would be on the single metal layer
You can see that we didn't originally plan it this way because of the kilmat we laid down; we realized later.

We then fit the metal frame that comes with the C.R. Lawrence windows so that it sat between the inside and outside layers of the metal frame of the vehicle and screwed the window in that way. To prevent the now cut inside layers from rattling, we added butyl between them and the C.R. Lawrence frame and that was that! No risk of cutting too big of a hole or of cutting into the outside metal frame of the vehicle unnecessarily!

placement of the C.R. Lawrence metal frame into the space between the outside wall and the interior metal layer
See how the frame fits into the space between the outside wall and the inside metal layer?

So, what we thought would be really complicated based on what we saw out there turned out to be easier than the rear cargo door windows!


Having explained install considerations, I wanted to share a couple thoughts on aesthetics. Now, no one is likely to see both sides of your van at the same time so, there is less symmetry and other aesthetic thought that needs to go into how matched up both sides of your van are. We still decided to place all of our universal windows, regardless of what side they were on, on the same horizontal axis.

However, we definitely suggest putting thought into the aesthetics on each side of the van at least. On the sliding door side, we knew that the universal window is not as tall as the sliding door window and decided to line up the centers of the windows (you can’t line up the top or bottom edges because of the problem with the double/single layers of metal).

Since the cutout on the other side of the van would measure the same from all edges, it was easy for us to create symmetry between the two sides of our van and so all of our windows are on the same horizontal axis, as well as vertical axes.

Anyway, just a thought! On to the actual install:

Tools, Equipment & Supplies

  1. C.R. Laurence Universal Vented Windows (the kit comes with the metal interior frame and hardware; we purchased with Van Windows Direct - great price and great customer service)

  2. Painter’s tape and plastic cover to collect metal shavings inside

  3. A Phillips’ screwdriver and hammer (you can also use a pick instead of the Phillips for one of the steps below but will still need the Phillip’s later on)

  4. A whiteboard marker or grease pencil