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Framing a new window opening for finless-replacements

Framing a new window opening for finless-replacements

Old 12-08-08, 11:22 AM
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Framing a new window opening for finless-replacements

Hi all. I'm new to the board and glanced around with no luck finding an immediate answer to my question. Here's my dilemma...
I am remodeling a mud room and planning on adding new windows (a double unit casement and a single casement). I am altering the dimensions to accommodate these. Normally I realize DIYers would simply buy new install windows with nail fins and nail them up and build jambs around them. However I bought some surplus replacement windows so I don't have that luxury so I know I am going to be framing for these differently. Can anybody refer me to a good resource or explain the best way to go about this. Clearly I will frame in a rough opening in 2x4s that is slightly larger than the window units, but I am concerned about flashing (since these don't have built in J-channels) since there wouldn't be a slope to drain water away unless I frame that in. What's my best bet to prepare before the window? BTW I have vinyl siding on the outside of the house and 2x4 framing. Any advice? And yes I realize this is not the "recommended" way of doing replacement windows.

Last edited by single_digit; 12-08-08 at 11:24 AM. Reason: Omission
Old 12-08-08, 11:55 AM
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Buy window sill and nosing at a lumber yard or Box Store. Rip side and top jambs from 1 x 6 to the depth required for your wall thickness. Cut the side jambs at an appropriate bottom angle (about 14 degrees). Build a window frame, install stop, install repl windows.

If the existing framing will not allow you to do the above, I'd install stop at the outermost location you can (maybe even the exterior of the studs), and put the widows (well caulked) as flush to the exterior as possible.

Use z-flashing/drip cap on the top, and hope the water that hits the window directly, will shed thru the window weep holes.

Theres a couple of REAL carpenters here that will prob have better ideas. Give 'em time, some people actually have to work for a living...lol.
Old 12-08-08, 04:14 PM
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If you can't get nailing fin from the window company that will fit your windows (many replacement windows accept a snap-on nailing fin) then Gunguy's instructions about building your own window frame is probably your best bet.

You're sill on the bottom should be wide enough to hang over your vinyl siding on bottom by at about 3/4" or so. Your jambs will be equal to the wall thickness. Build the interior dimensions of the jamb about 1/4 to 3/8" bigger than the window is so that you have a snug fit. Normally windows set back about 2" from the face trim, so that's probably where you'd line up the blind stop (the stop the window pushes up against). Hopefully some sill expander came with the windows (sill expander is used on many windows to take up the gap between the window and the sloped sill).

As Gunguy mentioned, you'd want to install a drip cap over the top of your exterior trim, which could be a standard #908 brickmould.

You'll want to build the window jamb first... make sure the windows fit into it... then take measurements of your jamb and cut a rough opening that is 1" bigger than your actual window jamb. You're best bet will be to remove all the vinyl siding in the area you will be working. You can unzip it above the window, and unhook it from the nails- leaving the nails in place often makes it easier to hook the siding back up in exactly the same place when you are ready to reinstall it. Start from the top and work down, removing only as much siding as you need to cut your RO.
Old 12-26-08, 11:48 PM
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Thanks for the advice. I have started building a frame around it with stops to hold the windows in place. The frame is 1x6 ripped to 4 3/4" (1/2" drywall + 2x4 framing +3/4" sheathing). I plan to frame in a bit bigger than the outside of all of this and then shim it all in to place before nailing. On the bottom side so far I have specially cut a piece of 2x4 to transition from flat 3/4" to tapering down at ~20 degree angle to act as a lower drip edge (I plan to do something similar at the top). I figure that having the break between this and the window casing be back up under the window (and the stops) will prevent it from leaking any more than I have to. My description probably doesn't make a lot of sense, but essentially I am following what I believe Xsleeper is describing with some additional details. I plan to make good use of peel n stick flashing on this project as well... Thanks for the input and feel free to give me any additional ideas.
Old 12-28-08, 05:16 PM
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frame window

On your bottom peice that hangs over the siding run a saw kerf across the bottom about a quarter inch back from the front edge.

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