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Old Yesterday, 07:00 PM   #1
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Building Window extension jambs


I'm deciding what to do with my window returns. I have 7 windows that are all about 3' x 6'. The returns are about 4 1/2" deep.

I've done some research and some options that could work are:

1. Drywall returns with metal corner beads. J-trim on the drywall edge that touches the window. I've got plenty of scrap drywall sitting around. A variation of this is to use Denshield (waterproof sheetrock) for the sill.

From what I've read this is a builders grade window return solution. Not a very moisture tolerant surface. Also not great to clean frequently -again moisture being the issue. I could also do densheild all around the window returns. I've got enough scrap.


2. Wood returns with an extended sill. Would require some ripping (I've got a table saw). I could install some type of narrow trim to cover the sheetrock / wood corner to create a modern look. I don't have room for standard trim (one of my windows is right next to the adjacent window). I could paint / stain the wood to complement my bronze windows, adding the appearance of depth to the window.


The window return depth is around 4 1/2". But it's plus or minus a little bit on each window. I could buy or make a taper jig(s) to accommodate the non squareness of the window returns. It's caused by the non levelness of walls not the window positioning.

One window return depth is way off. Again it's caused by the walls. (See diagram). Is this going to cause some issue building wood extension jambs?

Any thoughts on sheetrock (or denshield) vs wood extension jamb returns?

Thanks
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Building Window extension jambs-img_6908.jpg  
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Old Yesterday, 08:17 PM   #2
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Re: Building Window extension jambs


If you want to do wood you will need a simple jig for the table saw to cut the tapers.

We built mostly houses that will be sold and every builder seemed to have a different way to trim windows.

We see just drywall and some times they add the trim with a setback so it still looks like wood.
We see MDF which can't handle water any better than drywall .

Sometimes we see drywall with a wood stool

Lately we see a plywood stool tiled with white tile.
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Old Yesterday, 08:35 PM   #3
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Re: Building Window extension jambs


Taper jig.
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Old Yesterday, 08:35 PM   #4
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Re: Building Window extension jambs


What's the color palette of the home going to be? What look are you going for?

You can do any number of things. If its wood or PVC, building the boxes on the ground are easier if the openings are consistent.
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Old Yesterday, 09:28 PM   #5
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Re: Building Window extension jambs


Quote:
Originally Posted by Windows on Wash;
What's the color palette of the home going to be? What look are you going for?

You can do any number of things. If its wood or PVC, building the boxes on the ground are easier if the openings are consistent.

White walls, wood floors (on the lighter side). Open living space. White kitchen cabinets. Stainless appliances.
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Old Yesterday, 09:32 PM   #6
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Re: Building Window extension jambs


I went with building my boxes first and my depth was just over 5.5", fortunately I had a bunch of 1x8 so ripped them all. There was some variation and where some extended a bit too far I used a 10" block plane sliding on the drywall, worked surprisingly well. Love those nice curls. I primed mine befoe I installed them then white paint and standard window trim.

The shimming varied a lot so had to innovate to make that a bit faster. Trim gun helped a lot.

With the variations you are dealing with it is probably going to be one at a time.
Not sure what to suggest for trim.

Bud
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Old Yesterday, 09:32 PM   #7
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Building Window extension jambs


Quote:
Originally Posted by Nealtw;
Taper jig.


Neal Iím going need more help than that. How does it work?
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Last edited by jaketrades; Yesterday at 09:35 PM.
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Old Yesterday, 10:09 PM   #8
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Re: Building Window extension jambs


Quote:
Originally Posted by jaketrades View Post
Neal Iím going need more help than that. How does it work?

You start with a piece of plywood or what have you more than 6 ft long.

Plywood is orange add a fixed fence to one side and a a cross piece at the end you will push on. (brown)
Set a loose fitting fence in there ( tan)



Measure all the pieces you want to cut and cut your jig to match the biggest measurement you need. And cut the jig to that.



Let's say your biggest is 6" on on end, you cut the jig so measurement 1. is 6 inches and use a wedge at the other end to get the small measurement.

Cut all the pieces that have a 6" end.

then you can use a wedge at both ends to get the smaller cuts or you can re cut the jig to fit each size as you go from biggest to smallest.
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Last edited by Nealtw; Yesterday at 10:13 PM.
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Old Yesterday, 10:26 PM   #9
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Re: Building Window extension jambs


Quote:
Originally Posted by jaketrades View Post
Neal Iím going need more help than that. How does it work?

If you have a ripping jig for plywood and circular saw you can use that instead.

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Old Yesterday, 11:54 PM   #10
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Re: Building Window extension jambs


I cut mine freehand on a table saw. It is not hard to cut a straight line.
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Old Today, 01:05 PM   #11
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Re: Building Window extension jambs


Since you didn't put a wood buck around the openings, I would case it in wood, painted. Renters like to hang blinds, curtains, blankets, and lights, over and over and over. And leave windows open.

If you do drywall, which is much easier and cheaper, you don't need the J channel at the window butt just a clean cut and caulk.

But I can't tell from the pics how much of the window frame is exposed on the jambs to fit either 1/2" to 3/4".
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