One of our key priorities for the van was more light and more airflow. We liked the awning window idea, and the best option we found for behind the driver was Eurovision windows.

We received a 450x1100 mm (approx 18” x 43.5”) window from Tern Overland a few weeks ago. It’s similar to the Dometic Seitz S5 window: awning window with dual-pane acrylic frameless sash, interior sliding screen and blind. We chose 450x1100 to fit as well as possible in the driver’s side B panel. It’s not full frame, but it fills the panel quite nicely. I think optimal would be a 500mm height, but that wasn’t an option. The 550mm height might fit (barely) but I think the blind assembly would be tight, even with a max thickness inner frame. The windows come with different trim kits for variable thickness walls. We have the interior trim panels, and I wanted to reuse them, so selected the 45-55mm trim kit, which is the thickest option. (The plastic panel has two foam insulation blocks 2” thick between it and the sheet metal, so I figured I would have 2” behind the panel… silly me).

I built a 2” thick inner frame from 4 layers of 12” baltic birch plywood. A bit of a jigsaw puzzle because I was trying not to waste wood. It would have been a lot faster to just cut each layer of the frame as a single piece, but would have taken most of a sheet of plywood. (Far cheaper based on time value of money, but I didn’t have an obvious use for a bunch of 18x40” scrap and wasn’t prepared to waste the wood).

stacked plywood frame

Next was removing the center brace from the sheet metal wall to make room for the window. I drilled out the spot welds using a spot weld cutter - another tool I haven’t used before. The self-centering retractable pin was quite useless since I couldn’t get the drill perfectly perpendicular to the weld. Drilling a pilot hole for the pin to sit in fixed that though. After drilling the four spot welds, prying the brace off was straightforward - the adhesive used seems to be made to be removed, which is nice.

spot welds

I’ve already cut one hole in the van for a fan, so tackling this (much bigger) hole wasn’t too daunting. Another thing I’ve not done before though. Using a jigsaw for the fan worked, but the edges were pretty messy. I looked at other approaches and the Sprinter World window install looked very clean and easy using an electric sheet metal shear. I have a bit of a new-tool addiction, so here was another opportunity! I picked up a DeWalt DW890 because it was available today, but I want to compare with cheaper ones at some point.

Always do a test cut with a new tool!

test cut

A little bit of warping, but that should be easily correctible, and the cut is cleaner than with a jigsaw. It does require a larger hole than a jigsaw - I used my slugbuster knockout 12 to make a larger hole (it’s about 34”)

Since I already had the inner frame built, I lined that up on the inside with the horizontal braces and traced the window dimensions. The frame is slightly larger than the window, so I repeated with the inner trim ring from the window to tighten up the lines.

In case the interior braces weren’t square to the outside features, I drilled some holes and measured on the outside. Within 18” over 3”, so not noticeably off level, but I adjusted anyway.


I asked my lovely assistant to hold the metal in place while I cut it. MsNomer used L-brackets bolted to the metal, but I wasn’t that sophisticated - a couple of finger holes should do… (I did use the same duct tape trick from the Sprinter World video as well)

finger holes

Because of the window location, I decided to cut from the inside. In hindsight, bad idea. I was happy with three of the four corners, but with one I got the metal shear caught against an interior brace and messed up the corner. See bottom left. It is covered by the window frame, so no big deal, but still annoying. Next window I’ll use the transfer punch method and cut from the outside. My idea was to avoid running the sole plate of the metal shear on the exterior paint, but it wasn’t worth the effort and error.

intial cut

I was very happy with how clean the cut was - and no little steel shavings to clean up or find rusting in the bottom of the van later.

Removing the scrap:

removing scrap

I’d recommend cutting 116” to 18” larger than the trim ring for next time, my cuts were tight, and required some clean up with the electric shears and a file to allow the window to fit. After ensuring the window fit, I primed all the cut edges and attached the inner frame with VHB 5952 foam tape. The 3M VHB application techniques recommend 15 PSI pressure for best adhesion, so like ThomD I clamped the frame to the sheet metal for a few minutes while working on other things.

bar clamps

Now to try fitting the factory panel… Sadly, my 2” measurement of depth between factory panel and outer wall was off. It was accurate at the bottom and middle of the panel, but at the top the panel and outer sheet metal were much closer together. I salvaged the situation by first cutting a hole the size of the window and test fitting. The bottom is OK:

bottom OK

But the top is too far out.

top NOK

Now rather than overlapping the factory panel on top of the inner frame, I cut it back further around the frame. Now it fits, but it’s recessed from the frame. Fortunately with black on black it’s not too obvious.


With the deep trim ring, getting the screws lined up through the inner trim ring to the window is tricky. Tern Overland nicely supplies a small straw to hold the screw while inserting it, but it still wasn’t easy. A magnetized screwdriver would have helped, but I couldn’t find my magnetizer

I only used the supplied rubber gasket, and it flattened the sheet metal nicely. I saw no problems with gaps at top or bottom after tightening all screws appropriately - everything looks even. Tern does recommend using SikaFlex 252 or similar for installs with more wall curavture, but as far as I’m concerned that isn’t necessary for the Promaster.

Overall we’re very pleased with the window so far. The full awning lets in a nice breeze, the blind/screen combo works well, and the awning adjusts to several different opening angles.

Here I’m closing the screen, and the window is at max opening:

screen closing

Here the screen and blind are both visible. The blind has a reflective coating:

screen and blind

UPDATE 2018-04-10: I compared the DeWalt DW890 metal shear to the similar Harbor Freight model, which was much cheaper. It looked almost identical, but with the DeWalt I had little to no difficulty making the small-radius curves needed. With the Harbor Freight shear, it cut very nicely in a straight line, but getting it to curve proved impossible. Maybe it’s my technique, but the DeWalt was much easier to manage. So I kept the DeWalt even though it was much more expensive. I’d still recommend trying the Harbor Freight shear and see if it works for you - much cheaper than the DeWalt if you can make it work for you.

UPDATE 2018-06-05: There can be a bit of rattling within the screen/blind roller when traveling over rough roads, but I expect we will have enough other things rattling that it won’t be a bother.