Replacing the Cabover Window

I was suspicious of whether the cabover window could be reliably sealed against leaks, and finding that it had been sealed shut by a previous owner pushed me in the direction of keeping it sealed shut. A MaxxFan Deluxe fan will be installed above the bed which should be sufficient for ventilation.

The original window is made of two panes of glass laminated together – perhaps to reduce the chance of breakage from flying stones. Moisture had made its way between the panes causing a fogginess around the edges. In the photo below you can also see the aluminum tape that had been used to seal the window shut.


I began by removing the operable parts of the window and taking them apart to measure for new glass. Two Dual Pane windows were ordered from that were 21″ x 9″ x 3/4″ Low-E / Clear glass. I was concerned that this would add a lot of weight, but the actual thickness of glass is the same as the original panes and with the removal of the window operating hardware the total increase in weight is only about 2.5 lbs. I bedded the new glass in the frame with TremPro 644 RTV General Purpose Silicone Sealant. I’ve used the same product to install the glass in Vista View windows in my Airstream and it has held up very well.


With the glass being 3/4″ thick it comes flush to the front of the frame.

I then made piece to cover the joint and finish it off using .032 aluminum. The aluminum is bent on the outer edge and bottom where it will be sealed to the trailer and is stuck to the glass and frame with TremPro 644. The plywood that I’ve used to spread the clamping force is also the template I used with a router to remove the centre of the aluminum.


The final photo shows the windows installed. Before replacing the window frames I installed generic weather stripping to seal them against the back frame.

At the bottom of each window I drilled and tapped two holes from inside the trailer into the frame to bolt the windows shut. At the centre, between the two windows, I added a piece of aluminum that I milled to fit from solid bar which is also drilled and tapped and bolted in place from inside the camper. That piece trims out the centre nicely, but also serves as a backup to keep the windows closed. There is still plastic film on the aluminum. I’m considering a way to add a polycarbonate stone guard.

In this photo you can also see the strip I added to lower the cabover – more on that in a future post!



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