windowsill depth

elizawhyzaJuly 19, 2012

Our trim is being done, and we've been told that the widest windowsill we can have is 2 5/8". Where we still have older windows in another part of the house, they are 2 3/4".

Our contractor said that newer Andersen windows are meant to be picture framed, which for some reason makes it impossible to have wider sills.

Does this sound right? I don't know enough to assess this myself.

My preference would be to have slightly more than the 2 3/4", so getting less than that is a bummer.

Thank you for reporting this comment. Undo


The image below is pulled off of the Andersen Windows website (see link below). The window unit that comes from Andersen is shown in orange. Everything in blue and green is supplied by your builder. There is sometimes a bit of disagreement about how some terms related to windows are used so, for clarity I'm going to use them as they are labeled in this diagram.

It is clear to me that what you really want is a deeper "stool" ...maybe because you envision setting small flower pots on the finished window sill. The stool can be made as deep as you like. The stool fits up against the "window sill" which is part of the window as it comes from Andersen.

The stool is a flat piece of wood that should be set so that the top is at exactly the same height as the window sill. (That way, your "finished window sill" is the depth of the Andersen window sill plus the depth of the stool. Make sense?)

Then, beneath the stool, and at a 90 degree angle to the stool is another flat piece of wood called the apron. The apron helps to support the stool. Where the stool is fairly shallow, a piece of 1/2 inch or 3/4 inch quarter-round is usually used as finishing trim under the stool where the stool and apron meet. This finish trim also helps to support the stool.

But, if you want a deeper stool, you simply choose a larger and perhaps more elaborate piece of trim to replace the quarter-round. The wider trim provides additional support to the deeper stool. If you want to go with a really wide window stool, use some metal corner braces to support the weight of the stool and then hide them with a piece of crown molding trim. And obviously, you would need to make the apron taller to keep things in scale.

If you're going to paint your windows, the line where stool and sill meet is puttied in and sanded smooth before painting. If you're planning on staining the windows, The stool must be cut very carefully so that the two pieces fit together without gaps when they are glued together. Any white glue that squeezes onto the top surface should be thoroughly cleaned up at once so that it doesn't show when you apply stain.

Builders like "picture framing" windows because it is very easy and cheap to do. That doesn't mean picture framing is the ONLY way to frame out modern windows. If it were, historic homes would not be able to be be updated with modern energy efficient windows while maintaining their historical look. Any reasonably competent carpenter should be able to frame your Anderson windows to achieve the look YOU want.

Here is a link that might be useful: Andersen windows

    Bookmark   July 19, 2012 at 12:34PM
Thank you for reporting this comment. Undo

My spec specifically says no picture framing. I am not sure what it is, actually, but it sounds like you would need more elements to not picture frame.

I did not realize that what my contractor has done is picture framing. He mentioned that the windows were set up to do them that way, but I thought that because we discussed it before, that he wasn't using the picture framing approach.

The casing is about 3.5" wide. What would be the max stool that would look good with that, in your opinion?

    Bookmark   July 19, 2012 at 12:42PM
Thank you for reporting this comment. Undo

OK, now it makes sense! I asked the contractor, and they are now going to cut the stool at an angle so it will be level with the sill. The way they first did it was different. The sill was higher than the stool, so I could see the entire "border" around the window that comes with the window itself. Now the stool will appear to be wider because it will incorporate the width of the sill into its surface.

How much of a reveal do you like to see on the sides and top? I think I prefer to see less of the border that comes with the window.

    Bookmark   July 19, 2012 at 1:28PM
Thank you for reporting this comment. Undo

One more addition here: I found a post from the window forum from a couple of years ago, and I have a follow up question.

Our windows have jamb extensions on all four sides. If you read below, it sounds like with some companies you don't have to have the jamb extension on the bottom. This would allow you to avoid using a sill cap over the existing jamb extension.

If you already have the jamb extension, it is ok to remove it? I wonder if it would void any warranties?

"Follow-Up Postings:
RE: Inside Sill or Picture Frame?

clip this post email this post what is this?
see most clipped and recent clippings

Posted by galefarm (My Page) on Fri, Jul 31, 09 at 15:45
Most windows come set up today for picture framed trim, however it is easy enough to convert to an interior sill which is how all my historic reproduction customers request their windows. A sill gives more room if you like to have nick nacks on the window sills, or if you put Christmas Candles in the window. A picture framed approach is a more contemporary look. as far as the outside goes if you want a sill appearance yo can do it one of several ways. 1) order the window with a subsill applied and they should come in you choice of thicknesses. 2) Order the standard window and apply a flat or brick mould trim on the top and sides with a sill profile on the bottom of the window. This can b in wood, a composite material or a clad material.
On the inside you can apply a window sill in one of two ways. One is to just apply a sill cap over the existing Jamb extension. Another way is to take the bottom jamb extension off and make a sill cap to replace it, or some companies will let you order the window with the jamb extensions on three sides only this is the easier way with companies that wrap their Jamb extensions on.

Basically it depends on your taste today whether you have a sill on the window or not In most cases the picture frame approach works very well."

    Bookmark   July 19, 2012 at 1:44PM
Thank you for reporting this comment. Undo

I don't think there are any hard and fast rules about depth of the stool. I personally think a stool about the same depth as the width of the casing casing usually looks nice.

Hopefully your specs say something more than just "no picture framing" or you're lucky your builder is actually casing the windows at all and not just wrapping the drywall around to meet the window. Like this...

Ugh! Reminds me of an eye with no eyelashes!

    Bookmark   July 19, 2012 at 2:19PM
Thank you for reporting this comment. Undo

Thanks, bevangel! No, it doesn't look like the picture at all!

I just did not like that the stool was lower than the sill. You could see the entire extension jamb as a rectangle around the window.

They will now do it so the stool meets the sill "flush", and they are going to show less of a reveal on the other three sides. I will send a picture later. They are working now so I don't want to take a picture.

I agree that the photo you sent is not the look we're going for! I have lived in several 18th C houses, and even on built in 1682, so my preference is for an older look. I want to see the trim, not the jamb. I know we need a reveal, but I would prefer to see just the angled "bevel" if you will, not the flat part of the extension jamb. My current house is only 32 years old, but it's a rambling cape that now has a cedar roof, hardy shingle on the front, and smooth hardie plank elsewhere. By no means is it a reproduction, but certain details matter to us a lot, and this is one of them!

    Bookmark   July 19, 2012 at 2:30PM
Thank you for reporting this comment. Undo

Just saw your follow up posts.

Are the interior sills of the windows (as they come from Anderson) angled or do they have a beveled edge? Mine (from Jeldwen) were cut square so placing a stool up against the sill would have been no problem at all. We opted AGAINST having deep finished window sills because I didn't want to be tempted to set plants in the windows. (I have a tendency to overwater my plants and end up with a pool of water under them which would not have been good for my wood framed windows.)

The thread you reposted from galefarm about jamb extensions is a bit confusing because he/she talks about both the interior and the exterior window finish at the same time.

I would not recommend having an exterior window sill. Even when properly sloped so that water runs off, an exterior window sill provides a place where things like wet leaves/snow can collect.

On the inside, you can just apply a sill cap over the existing jamb. I would NOT remove the lower jamb without first contacting Andersen regarding whether this would void their warranty. And if their agent said that it would not void the warranty, I'd want it in writing with a statement that the agent had the authority to bind the company. Window companies can be VERY picky when it comes to their warranties.

    Bookmark   July 19, 2012 at 2:38PM
Thank you for reporting this comment. Undo

They are beveled. The carpenter is cutting the stool so it lays on the bevel of the sill. It looks really good, and you don't see the extension jamb at all, like an old-fashioned window sill.

Thanks, again, for your help.

    Bookmark   July 19, 2012 at 3:33PM
Thank you for reporting this comment. Undo

It's difficult to follow this discussion. A window "sill" is the exterior part of a window frame that slopes to shed water. Modern windows have very small low-sloping sills and can be "picture framed" which means the same exterior casing trim is used on all 4 sides. This often causes leaks below the window and should be avoided. Instead use a PVC "sub-sill" to create more projection, a better "drip-edge", and a place for the jamb trim to terminate.

The lower trim on the inside is called a "stool". It creates a better seal at the bottom sash and a narrow tapered "apron" trim is placed below it. Modern windows are no different from older windows in that the stool can be added or omitted. When it is omitted the casing trim is the same on all 4 sides like a picture frame which has a 60's modern/utilitarian/office appearance.

I'm not sure what is meant by beveling. A photo would be helpful.

    Bookmark   July 20, 2012 at 5:26AM
Thank you for reporting this comment. Undo

As I said, variations in what is meant by some of the terms related to windows can cause confusion. That's why I started my response with a labeled diagram taken from Andersen Window's website showing the interior of a window and then used the terms as Andersen Windows used them on their website.

OP did not have any issues with the exterior trim out of her windows. She just wanted a wider flat surface on the INSIDE of her windows so she could set plants/knickknacks in the window. Since OP (and apparently her builder) were able to follow the discussion well enough to solve OP's problem, whether the particular part of the window trim that was in question is properly called a "stool" or a "sill" - or something else altogether - seems irrelevant.

I'm sorry to have confused you tho. Hopefully if anyone else has a similar problem, they'll find the diagram helps to clarify things.

    Bookmark   July 20, 2012 at 9:24AM
Thank you for reporting this comment. Undo

The issue here is how an Andersen window is detailed differently from a traditional window which is difficult to discuss because Andersen makes many different designs and apparently the model is not identified.

For an Andersen Woodwright double-hung window the statement that newer Andersen windows are meant to be picture framed is true for the exterior trim but not the interior trim. The use of a stool vs Picture frame trim is entirely optional.

But I suspect the contractor either misspoke or was misquoted because he was probably saying that the presence of a weather lip at the bottom interior edge of the sash allows the window to have "picture-frame" trim because a stool trim is not needed to seal the window sash as it normally is on an older window.

It is also true that the presence of this permanent weather stop makes Andersen's standard stool trim about 3/8" shorter.



    Bookmark   July 20, 2012 at 11:51AM
Thank you for reporting this comment. Undo

The confusion that seems to have arisen here appears to be due to a misunderstanding of why modern windows have an integral upturn or weather stop at the bottom interior edge of the frame/sill. It is not for the purpose of accommodating "picture frame trim" although it does take the place of what originally served as a weather stop: a stool trim added in the field.

The reason these upturns were added was to be able to get higher air/water penetration test ratings with the basic unit since a field applied stool would be ignored in the modern test, would not stand up high enough to be very effective and would not accommodate a weather strip.

So today windows have improved weather/air penetration ratings but pretty dumb looking stool details. Windows made for higher wind areas have even higher upturned weather stops. Unfortunately, window designers care more about how a unit will fit in a shipping box than how it will look when trimmed in the field. It takes a good carpenter to make a modern window look good no matter what you paid for it.

    Bookmark   July 20, 2012 at 3:21PM
Sign Up to comment
More Discussions
Just got first set of plans - would love feedback!
Hopefully, the below is a link to the first floor of...
Open Cell Attic Insulation. No baffles/No vapor barrier?
We are in Chicago and are putting on an addition that...
building a simple modern farm house on a budget
I am planning to build a simple modern looking farmhouse...
NEW to New Build - A/C Option Input Needed
I've been lurking around this board for a few weeks...
Please review my plans - help needed with bedroom arrangement
Hi folks! This is the second time I have posted our...
Sponsored Products
Mat├ęgot Dedal Bookshelf - Red - Gubi
$349.00 | HORNE
Broan-Nutone Unfinished Wood Arched Louver with Polystyrene Body 16W x 24H in. M
$115.93 | Hayneedle
the great outdoors by Minka Lavery Posts 3-Light Outdoor Corona Bronze Post
Home Depot
Metlev Wall Clock by LEFF Amsterdam
$119.00 | Lumens
RION Furniture - Tanta Chair, Pale - SOF252P
Great Furniture Deal
TOTO Vessel Lavatory w/ SanaGloss
Modern Bathroom
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™