# 12" deep window returns



## wwsteel7 (Jun 16, 2016)

Hello all...I've been lurking here for a little while now and am wondering how best to finish my deep window bays.
I'm a drywaller...not a carpenter. But with a little good direction I'm sure I can finish my windows correctly.
Basically...I've got 4 deep window bays that I want to make each the bottom sill into a shelf.
I haven't installed any mud or bead yet to either the outside corners or inside against the window where the butts into the window. The bottom sill is not 
drywalled...only the 2 sides and top.
How would you finish in and around these windows to achieve a contemporary look?


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## GeorgeC (Jul 30, 2008)

I guess I am puzzled by your question. I would think that you would just use wider material than normal. That is use 12" material instead of the normal 4' or 5' material.

What is contemporary look for a window?

George


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## wwsteel7 (Jun 16, 2016)

I'm trying to avoid curves or half round truly. Just flat/square

I guess I'm not sure if I should have drywalled inside at all...maybe just stained 1/2" mdf 12" wide wrapped all around ??
Or having drywalled the 2 sides and top...I'm not sure how to finish the outside corners


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## GeorgeC (Jul 30, 2008)

Now you really have me puzzled as to what you are doing. Are you saying the surfaces are not flat?

A sketch would sure help.

George


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## Brian(J) (Feb 22, 2016)

Hi,
would this be a possible solution? The casing was kerfed and the softline sides and corner bead top and bottom legs were inserted into the kerfs.


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## Brian(J) (Feb 22, 2016)

To add to my previous post, I'm not sure how far you may have painted yourself into a corner with the framing, window sizing, and drywall you have already done. How thick material can the bottom sill be? Thicker would be better.
Did you corner bead the sides right back to the window?
Anyway, a contemporay look implies a trimless look and another approach might be to use 1" material, make the bottom, top, and sides out of it and shim it to bring it out flush the wall with the shim forming a reveal line to the drywall.

The image show the sides but the same condition would occur all the way around. The idea is everything flush with no added trim.


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## m.n.j.chell (May 12, 2016)

I don't have any advice for you, just wanted to say, Welcome to the site, wwsteel7. 

Brian ... handsome dog you got on the stairs.


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## wwsteel7 (Jun 16, 2016)

Here are a couple pics of window well with no drywall or mdf yet


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## wwsteel7 (Jun 16, 2016)

One more


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## wwsteel7 (Jun 16, 2016)

Looks like my pics not getting uploaded.


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## Steve Neul (Sep 2, 2011)

Without more specific info it's difficult to say how to proceed. If you are just needing advise on plastering work that is simple enough. Use the mesh type joint tape. Use metal outside corners. Use a lightweight drywall compound and apply it as smooth as you possibly can as though you don't intend to sand it. It's a whole lot easier to add more coats than blob a bunch on and try to sand it level. It's unknown how the rest of your drywall is finished out but the style today is to sand the drywall smooth and paint it without any texture.


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## TimPa (Jan 27, 2010)

what you are referring to are jamb extensions. elements that are on the inside surfaces of the window well, between the window and the wall surface. 


many folks build a 4 sided box, sized to fit inside the well with maybe a 1/4" gap all around. slide it in, shim around all sides, and tack it to the jack studs, header. I measure the well depth all around (window to wall), and make the box width the same as the deepest measurement I get. 


then you can insulate the gap and apply trim to the wall surface.


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## Hammer1 (Aug 1, 2010)

wwsteel7 said:


> Hello all...I've been lurking here for a little while now and am wondering how best to finish my deep window bays.
> I'm a drywaller...not a carpenter. But with a little good direction I'm sure I can finish my windows correctly.
> Basically...I've got 4 deep window bays that I want to make each the bottom sill into a shelf.
> I haven't installed any mud or bead yet to either the outside corners or inside against the window where the butts into the window. The bottom sill is not
> ...


You want to return the drywall to the window and not use wood extension jambs, you want the sill to be wood, I'm guessing. Typically, the wood sill is cut to fit with the front edge protruding more than the wall, if a molding goes under the lip, allow for that, if not, choose your own projection, normally about 3/4". The drywall will fit against the wood sill. Often, ears are left of the sill. You can use peelable L corner. Works like a J channel which goes against the meeting surface, then the part of the channel that shows peels off after taping.
http://hardwareonlinestore.com/inde...bG&ppcstrkid=1411601677&ppcsu=xhg7f5djqitnahs


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## wwsteel7 (Jun 16, 2016)

So building wall boxes...There is no need to drywall inside or bead?
Why shim the box 3/16?


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## Brian(J) (Feb 22, 2016)

wwsteel7 said:


> So building wall boxes...There is no need to drywall inside or bead?
> Why shim the box 3/16?


The 3/16" shim is for a reveal which is a purely decorative effect, a simple line that defines the window. Some modern architects like it, some don't. But sometimes the joint tends to open up and this prevents or hides that.


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## wwsteel7 (Jun 16, 2016)

Hammer if done that way...I would have to do the wood sill first...then drywall sides and top then install the J trim and mud?
Or I guess drywall first and compensate for the mdf?
I can only make the sill from 1/2" material due to window crank handle at bottom on sill.
So...If I said no to drywall and just did boxes...do you install piece at a time or pre build actual boxes with Kreg screws?


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## Brian(J) (Feb 22, 2016)

wwsteel7 said:


> Hammer if done that way...I would have to do the wood sill first...then drywall sides and top then install the J trim and mud?
> Or I guess drywall first and compensate for the mdf?
> I can only make the sill from 1/2" material due to window crank handle at bottom on sill.
> So...If I said no to drywall and just did boxes...do you install piece at a time or pre build actual boxes with Kreg screws?


If you are going down this road you might consider MDO as opposed to MDF. MDO, 'sign painter's plywood' uses water resistant glue and adds a paper face to both sides that takes paint well. 1/2" MDF won't take a screw as well and if water ever gets through the paint to any part of it you will have a gruesome situation on yours hands, this being a window and a shelf there's two reasons it might get wet.

I made my garage doors out of MDO and they are in great shape after 8 years in the weather, no overhang and south side of house.
One caution, the plywood under the paper can have those 'football' patches and they can show through, had I to do this again I would flip the panels around to hide those. There not terrible but when the light hits just right they show a bit.


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## Hammer1 (Aug 1, 2010)

wwsteel7 said:


> Hammer if done that way...I would have to do the wood sill first...then drywall sides and top then install the J trim and mud?
> Or I guess drywall first and compensate for the mdf?
> I can only make the sill from 1/2" material due to window crank handle at bottom on sill.
> So...If I said no to drywall and just did boxes...do you install piece at a time or pre build actual boxes with Kreg screws?


The window fits in what is known as a rough opening, (RO). This is larger than the actual size of the window. When the window is installed, it is, more or less, centered in the RO. The measurements from the edge of the window to side of the RO will vary. You cannot just attach any type of extension jamb directly to the side of the RO, it will need to be shimmed to stay in line with the actual window.

Rather than build extension jambs out of wood, a common method is to return the drywall to the window. In this case, shims are attached to the sides of the RO so the drywall will line up straight with the window jamb and account for the different measurements. Jamb edges are roughly 5/8"-11/16", so, shims that are placed flush with the backside of the window jamb work to leave about a 1/8" reveal around the window perimeter after 1/2" drywall is installed. The peelable L channel is placed on the edge of the drywall and fits against the window. You then flat tape against the L channel. After the mud is completed, you peel the peelable part of the L. This leaves a nice tight, straight line. It's the modern alternative to flat taping. Mud won't crack since it's not actually attached to the window. We use it on timber frames where drywall goes against a beam that will surely shrink.

You can drywall the entire extension jamb, top, bottom and sides. Use the normal outside corner bead where the extensions meet the wall, mud it all, prime, put on one coat of paint. Then make a paper template of the sill you want, transfer that to the sill piece, cut and install. Some only do the top and sides, install the sill, then use an apron molding under the sill. This is the easiest way to do a wood sill with ears and returned drywall extension jambs. The apron molding allows some wiggle room that will be covered. You see this method everywhere, medical, dental offices, motel rooms, just look around.

Casement windows have short turn crank handles available. Normally there is quite some distance from the RO sill to the inside perimeter of the window, unless it's an all metal window or something unusual. You can make the reveal at the window sill anything you want. In other words, if you leave 1/8"+- at the top and sides, you could leave 1/2" at the bottom and not be noticed because it's a casement. A word of caution, pros know this but others often make the mistake of cutting the drywall flush with the RO sill. A 2 1/2" apron molding may not cover this, we always leave the drywall up about 1 1/2" at the sill, it can be trimmed later as needed. 

If you make the extension jambs out of something like plywood, solid wood, etc, you build a box to fit, then install that as a unit. Some do it piece by piece but it's much easier to make a box. You place shims to align the box and fasten through those into the sides of the RO with finish nails. You didn't say what the house is made of, fastening to stone is different than wood. I would not recommend using MDF. Difficult to fasten on the ends and edges, surface can puff with finish nails, heavy, needs priming and sanding, may need several top coats, will swell with any moisture, miserable sawdust and smell. You will pay dearly in the future for the small savings MDF gives today. Use birch plywood, not Baltic birch.


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