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

Updated: Mar 15, 2021

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:

3.3: 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

  5. A Jigsaw – getting a strong, reliable jigsaw is really important – it can make the difference between cutting a window in 45 min. and cutting it in 20.

  6. T118A Blades for the jigsaw

  7. Metal file

  8. Rustoleum and applicator

  9. Drill

  10. Auto glass cleaner & paper towels

  11. Butyl tape


We installed each window one at a time. If you think you can get them all done in a day, go for it – I can see how it is more efficient to do all your cutting at once, and filing at once, and rust treating at once, etc. We just never know if the kids will throw us a curveball and we have to stop working and leave three gaping holes in our van.

1) Prepare the Area

You also want to prep the jigsaw. Line the whole metal plate with painter's tape so it doesn't scratch the paint of the vehicle as you're cutting.

With painter’s tape (the wider it is, the easier you can cover all openings) and plastic (we used our large Costco trash bags), tape up all openings and crevices in the van door, nearby walls and cover the van floor to protect from metal shavings.

We learned another little trick from Mathers on the Map (we love their videos!): Get thick painter’s tape and tape it in the form of a box around the area you’re cutting. The sticky parts will catch many of the metal shavings before they even drop on the plastic covering you’ve made.

2) Create an outline for the cut

Placement is a bit tricky (see above). We used the metal frame of the C.R. Lawrence window to figure it all out.

First, we figured out the horizontal placement of the window from the inside to make sure that we cleared both double-metal layers of the vehicle frame. We then marked the center-point between the two vertical edges with the hammer and pick so that we could see it from the outside.

2nd, from the outside, we measured the center of the sliding door window to figure out vertical placement of the window. Where those two axes met would be the center of our window placement.

3rd, we create a straight rectangle, given the measurements of the window, centering it on the point we created by matching up the horizontal center (from inside) and vertical center from the outside. That means 16 11/16” horizontally in each direction from the center point and 9 9/16” vertically in each direction from the center point. You can just draw this with the grease pencil or dry-erase marker.

With that rectangle in place, we could now draw out the curved edges of the window by lining up the C.R. Lawrence metal frame with the straight edges of the rectangle. Note: you’re lining up the inside edge of the frame (the outside edge is larger than the cutout).

Don’t forget to put painter’s tape on the outside of your line to protect the metal from the jigsaw (which you should also already have covered in painter’s tape, too).

the window cutout showing the taped edges to protect the metal frame of the vehicle
While this is already cut out, I just wanted to show the tape around the edges

Once you’ve done it for one window, you can do it much more easily for the other windows. If you’re going to have to back windows like we do, you can easily measure the cut of your second window by measuring the edges of your installed window from the factory-made indents and then just add the curved edges with the C.R. Lawrence metal frame. You can then line up your front universal window vertically with the window you’ve installed on the other side and create a center point for the horizontal axis from the inside.

the outline of the cutout with arrows to the edges showing where you can measure to line up the cutout on the other side
There's an identical cutout on the other side so you can measure the distance from the edges

OR you can just do the measurements separately for each window!

3) Cut the Hole

Grab your jigsaw and cut away, following your outline the whole time. Don't forget to tape the cut edge in place as you go to decrease the vibrations.

4) Smooth the Edges & Treat for Rust

File the window opening on all sides making sure to leave a smooth surface. Now you’re good to clean up all the metal shavings and remove the plastic and painter’s tape. Also, use the auto glass cleaner and make sure your metal frame is really clean and there is no debris left, especially where you’ll be placing the window.

With the applicator (we used a sponge applicator), apply the Rustoleum to the cut edge and let dry (approx. 1 hour).

the window cutout with rustoleum treatment visible while drying
You can see the rustoleum drying along the edges

5) Add the Butyl to the C.R. Lawrence frame & Screw in the Window!

You will need someone to help you out on this part, at least until you’ve got all your screws loosely in place – you’ll see how screwing into one layer of metal makes it a bit more difficult as it’s not as solid of an edge.

Before actually installing it, line up your metal frame with the cutout and mark where it slides in under the inside layer of metal. Add butyl tape to the four places where it will touch up against that interior layer.

Slide the top of the metal frame in between the two layers of metal. The interior layer of metal is now a bit flexible so you can pull it toward you a bit to make sure to slide in without disturbing the butyl. The bottom is much more flexible and once the top is in, you can easily get the bottom in too, again, making sure not to disturb the butyl.

Have someone hold the window from the outside as you start screwing the metal frame into it.

IMPORTANT: do NOT tighten the screws all the way one at a time. Rather, screw them in a little at a time until you have all the screws in. Then keep going around and around, tightening them more and more.

Once you’ve gone as far as you can go manually, grab the drill and give them all one last tighten and that should be it! You don’t need or want the glass to be touching the metal. It is properly installed if the window lines up with the exterior of the outside groove.

6) Test for Leaks

It’s nerve-racking, I know. Just do it. It will feel so much better when it is all said and done. Better figure it out now and fix it before you hit the road than blindly believe everything’s great when it’s not!

And that's about it on the window front - please drop any questions into the comments below or on social media. If you’re interested in following along with the build - electric and roof-top attic/deck/solar installs are coming up next! please hit the subscribe button at the top of the post!


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