Replacing interior window jamb....

For those self-installers
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Posts: 63
Joined: Sat Jan 21, 2006 11:02 pm

Replacing interior window jamb....

#1 Post by chrisexv6 » Tue Apr 25, 2006 6:53 am

Just had my new replacement windows installed. Most of them, the installers were able to rip everything out to the original rough opening, and then install the window from the inside. They capped/sealed the outside, I told them I would do the insides (to save labor $$$ and because I wanted to change the trim anyway).

After looking at the various configurations of windows I have, I came up with a couple questions.

1. Is it OK to use the door/window foam from HD (the blue can), in place of the pink fiberglass that the installers used to fill gaps? The foam is supposed to be minimally expanding, and I didnt mind using it for my old windows, but I wanted to be sure its OK to use on my nice new Schucos without bowing/breaking anything, and/or voiding the warranty.

2. Ive been told to use quarter round as a "stop" molding against the window. However, since I have no existing jambs, would it be OK to just run the jamb all the way up to the window frame? I can square the edges of the board off, and I think it would give a more finished look than tacking quarter round on top of the jamb. Also, in the case of my sliders, the bottom rail is rested directly on the rough opening (like it should be) so I only have 1.25" to work with. If I used 3/4" for the jamb, I wouldnt be able to put a quarter round up to the window anyway (not enough height on the bottom rail).

Thanks in advance!

Posts: 80
Joined: Fri Jan 20, 2006 3:57 pm

#2 Post by XSleeper » Tue Apr 25, 2006 9:26 pm

1. Don't know anything about the HD foam. I have only used DAP latex foam around vinyl windows. I would rather err on the side of caution.

2. Yes, you can run the jamb right up to the window. but what I've found to work best is to do both- a jamb and a quarter round (actually, I use base shoe, which is 3/4 wide, but only 1/2" thick. I'll make the jamb, nail it all together (with a stool, if needed) and then center that on the window, make it flush with the surface of the wall, shim it in place, and nail it to the r.o. Then if there is a gap between the jamb and the window, the baseshoe covers that. It's very hand to do it this way so as to avoid tapering your jamb if the wall thickness is goofy. Often, it'll be 1 1/4 on one corner, 1 1/8 on the other, 1 3/8 on another, and so on. Making the jamb one width and lining it up with the surface of the wall makes your casing miters work out a LOT better. And I think it looks good too when you have the baseshoe trimming the edge of the window.

See an example at: ... d37re2.jpg

One other thing I'll suggest. Prepaint all your stuff (or stain and varnish) but be sure to do the side of the wood that touches the window as well. I've found that if you don't, vinyl windows can sweat under certain conditions, and if the wood that touches the vinyl is not painted or varnished, mold can begin to grow into the wood. Painting/varnishing that side of the wood may not stop the mold from growing, but it will help prevent the mold from eating into the wood and showing up under your finish.

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Joined: Fri Apr 14, 2006 1:51 pm
Location: Portland, OR

#3 Post by mman » Wed Apr 26, 2006 12:39 pm

Read your guarantee/warranty carefully. Some warranties will be voided if any type of expanding foams are used. I suggest soft celled backer rod, or fiberglass insulation (piece by piece). These may take a bit longer to apply, but to do the job right will save you tons of time and money in the long run.

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