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Window casing for replacement windows in existing metal frame


I have replacement vinyl windows that were installed in, what I believe to be, the original metal frames. My house was built in 1955 and what I think is the frame is a hollow, tubular metal that is 1" thick. The frame protrudes past the surrounding drywall around some parts of the frame but the metal stool protrudes approximately 3/8" all the way across the bottom of the window. Given this, how can I install standard window casing? Pictures of what I'm referring to are attached.

I'm at a loss for what to do so any recommendations will be greatly appreciated.

Rodney H
Re: Window casing for replacement windows in existing metal frame

Well, I guess I would try shimming everything out flush with the bottom stool, kinda like making jamb extensions. Now, what do we do next ?? Mmmmm, I guess, if it were my window, I would cut some more pieces out of wood, widening the entire frame around the window, so it will not exceed the finished width of the casing you will be using, with no 'reveal" along the inside edge. By doing this. you will be covering all seams, leaving only the inside seam to see.

The new jamb extensions will have to be screwed to the metal case frame. Recess the screw heads when you attach them. They will be covered by the new casing, so you will never see them.

Now, add your new casing. I know, it might look a little different to have a thicker casing around this window, but, it will eliminate that notched appearance you have at the present time.

If the old case frame was wood, I would suggest you just sand it flush, but with metal it is a different story. If you are handy with a router, you could make, wider, new jam extensions with notches to match the different heights of the present jamb. By doing this, you will not have to worry about how to fasten the thin pieces on each side, and top of your window.

Hope this helps, just a little.

Good luck, and enjoy 2010.

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Re: Window casing for replacement windows in existing metal frame

I would add jamb extensions (some tapered) so the jamb is uniformly 3/8" proud of the drywall, then use casing to match the style of your home. Standard mitered casing will need a 3/8" filler added to the back of the outside edge of the casing.

The most forgiving style would be a back-banded casing. Then you could use a 3/8" thick flat casing with a back-band with a 3/4" deep reach on the outside edge. This covers the filler. The back band is usually just an outside corner molding. I leave a small space between the casing and back band. The space is hidden by the front face of the back band. The space allows movement without forcing back band miters open.

You could also just use 3/4" flat stock (1x4) with a 3/8" rabbet on the inside edge to receive the jamb extension.

Happy New Year,



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