HOW I INSTALL RADIUSED CORNER RV WINDOWS IN A CARGO TRAILER
Forum members have asked, so I though I would post it for all:
I only use windows that will fit in between the wall studs. I don't care to mess with the structural integrity of the trailer OR get into welding either aluminum or steel to reinforce a wide cutout.
I insulate and panel the inside of the trailer
before putting in the windows. It's simpler and faster than cutting the outside and later cutting the inside to match.
I take foam board from the hobby store/Dollar Store and press it onto the window's inside frame, then cut the indentation with a razor knife to make a template. I fit the window into the cutout on the foam board to see that it's perfect and that there's an eighth of an inch clearance all the way around the cut. Then I put the template on the outside wall of the trailer, square it up between the wall studs and trace the cutout.
I tape the outside of the line quite wide (4 inches) to protect the paint from getting scratched by the jig saw base. I also tape the metal jig saw base just to make sure.
I drill a quarter inch hole inside the window line anywhere for the jig saw blade. I drill it all the way through the wall, including the insulation and the interior paneling.
I put a long Bosch (brand name), fine-toothed plywood blade (available at ACE Hardware) in my Black & Decker jig saw and insert it in the quarter inch hole then cut the line. One cut. The long blade cuts through all of it. The aluminum skin is soft. No problem for the blade.
Use RV window tape (butyl tape) on the inner lip of window frame to get a water tight seal. The trim ring will suck down on the frame, squishing the butyl tape. (On a hot day it will really squish.)
Best wishes,
Prem

My goal...
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...is to live in a trailer.