How to trim out this window in basement???


Old 07-02-14, 10:45 PM
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How to trim out this window in basement???

Helping a friend do a finished basement. I have a fair amount of experience doing all sorts of improve fb stuff but this one has me stumped.
Finished was will be drywall, not sure if I should run drywall in window well area or do wood. Also not sure exactly how to work with how to tie into that casing(think that's what it's called)
Any info would be great!!!!! Thanks in advance!
Old 07-03-14, 06:56 AM
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If the style of casing will have miters at the 4 corners...

I would measure the distance from the window to the edge of the stud plus 1/2" for drywall (check all 4 corners... hopefully they are within 1/8" of being the same. Depending on whether it's painted or stained, that affects the material you choose... if it's painted, use poplar or MDF. You could use plywood if you want to veneer the cut edges. If it's stained, well... match the species of the casing. Rip pieces on a table saw, going with the smallest width, as measured above.

Next build the extension jamb like a frame. Figure out how big you want that frame to be. width x height. Usually you want your extension jamb frame to be symmetrical with the window. Plus, you want there to be a 3/16 to 1/4" step (or reveal) where this extension jamb frame is going to meet the inside perimeter of the window.

So it should be pretty easy to figure out the size of extension jamb you need. Take the inside measurements of the window... add the reveal (3/8") to each of those measurements... and (assuming you can use 3/4" thick material) add 1 1/2" for the thickness of the jambs. That will give you the outside dimensions of your extension jamb. Let's say you come up with 28 1/2 x 54.

So what I usually do is make the top and bottom pieces exactly that long.... 28 1/2" For the length of the side pieces, I'd subtract 1 1/2" because I want them to fit in between the top and bottom. So the sides would be 52 1/2".

If you ripped those pieces on a table saw, you have rough edges on the boards. Sand those if needed. Rough edge goes toward the window... nice finished or veneered edge faces the interior. Select the nicest face of the wood (sand it too) and orient it so that it faces the interior- that way any boogers or dents on the wood will face the cement.

Nail that jamb together at the 4 corners, then slide it into the opening to see if it fits nicely. (you should have that 3/16" reveal all the way around the jamb where it meets the window- shims will help center it.) If it looks good, pull it back out and put just a LITTLE glue or construction adhesive onto the outside perimeter of the window. Then slide the jamb in, center it in the opening as needed with cedar shims, push it in tight to the window and nail it to the studs with finish nails. You will need to insert some wood into those metal studs anywhere you expect to nail anything. Rip it to fit inside the metal stud, then use metal stud screws to hold it in place.

If you have room for it, you could foam the perimeter of this jamb with low-expansion foam. You would want to put the nozzle back where it would glue the jamb to the cement.

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