How does one fill a large void in a window sill?

[Steve]

Hello. The windows in my Mom's house were just replaced. Apparently they had to move the windows about 1/4" forward from where the previous windows were (according to the person who installed it, this was necessary to get a good seal so air couldn't get it - apparently the previous windows had not been installed correctly and didn't have a good seal) so on each window there's now about 0.25" space on the window sill (between the sill and the window).

I asked the window person what to do about the void. He said to fill it with a piece of wood so I'm attempting to do that. The other alternative I guess is to use wood putty or bondo to fill in the void.

I measured the void on one window to see what size of wood I would need. Upon doing so, I found out the distance between the window and edge of the sill (the depth measurement) varies significantly as you go from one end of the window to the other so that one piece of wood with the same cross-sectional area would not fit well.

Solving this is a headscratcher for me. The space seems too big to fill it all with wood putty or bondo (the size of the void on each window is roughly

35" wide, 1" high, and 0.25" deep so it would be a lot of wood putty or bondo).

I'm guessing the thing to do is fill each void with several pieces of wood, each piece having a different depth (since the depth of the void changes as you go from one end of the window to the other) and glue them in somehow (or nail them in with small nails and top it off with wood putty) and then fill around those pieces of wood with wood putty or bondo. And somehow make all this look like a continuation of the existing window sill after the sill and void are painted.

I'd appreciate any ideas on how to solve this problem. I'd also appreciate responses from people who have used a lot of wood putty (or bondo or whatever) to fill a large void like what I have and how it worked out.

Thanks!

Steve

[dpb]

the window).

My reply would be to the installer "you're not done yet".

The answer on the use of filler for such a fix is it's possible but not a real good solution. Really need somebody to do it that has the facility to fit pieces in. It's not too difficult but depends on what one has for tools and skills???

Alternatively, the other solution is to replace the sills or remove them and add the width necessary and then trim to fit when replacing.

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[Swingman]

Sounds like a perfect application for a piece of 1/2" "trim" or quarter round molding, painted the same color as the "sill".

What I'm not certain of is that your terms, "sill", "width", "height", "depth" are standard definitions, which could make any answer no workable.

Can you link to a picture?

[Peter Huebner]

Partly a question of personal taste. Some might suggest attaching a 1/4 round or concave moulding over the top, that certainly works. I personally would varnish/paint the window down into the gap (to seal the wood against any creeping moisture) and then put a thick bead of (tinted?) silicone into the gap and shape it concave making sure it bonds to both sides. Silicone should accomodate temperature-related movement of window and sill without cracking. Could even put enamel paint over the top of most products after the job's cured.

-P.

[Swingman]

"Dean H." message

IMO, in order for you to say that was indeed the case, you would have to know with certainty what kind of window was put in.

It is not unusual, for instance, for a modern vinyl window to be thinner behind the nailing fin than an old window, thereby possibly leaving a gap between the new window and the old sill when installed, as the OP reported.

In addition, the age of the house could be a factor. Thicker because framing lumber was a different dimension, 2 x 6 exterior walls instead of 2 x 4, etc.

That said, the "seal against the building" does seem to be a peculiar remark, although not impossible ... it would certainly make me want to ask some questions as well as take a close look at things like flashing and caulking with a practiced eye.

Unfortunately, as I builder, I rarely see a window company around here include redoing sills in the price of new windows unless it is specified in the contract at extra cost. That may just be a regional thing, however, since this is hurricane country and there are a lot of windows replaced, that could explain the practice, or lack thereof.

Replacing/redoing sills, means a trim carpenter, AND a painter, perhaps having to match paint, in many cases.

AAMOF, when called two weeks ago about a similar issue, I sent my trim carpenter and painter, as a courtesy, to a house completed two years ago to touchup the sills and casing on two new "sound proof" windows that the homeowner, being a light sleeper, replaced in the bedroom to keep out exterior noises.

[dpb]

Swingman wrote: ...

While I suggested OP tell the window company rep to "fix it", I'm sure their contract is written to allow them to claim it's not in the scope of work.

That said, I think it sucks weenies as a practice as one can be sure the sales rep didn't point out the likely or possible problem or that it wouldn't be covered when making the sale and it certainly is a detail I think virtually any homeowner would expect to be "made right" as part of an installation simply as being part of the "workmanlike manner" clause. Leaving a noticeable gap when done just isn't up to snuff imo.

$0.02, ymmv, etc., ...

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[Dean H.]

"Swingman" ...

I'm just going by the original poster's first paragraph. If the gap was caused by window design then the installer should call it what it is and not blame the previous installation. If the previous installation wasn't tight enough, that's the one that would leave a gap, not the new tight one. The logic of the installer's excuse is entirely backwards.

Um, a little quick math here...

2x6 vs 2x4 does not yield a 1/4" gap but more like 2". Maybe good old fashioned 2x4s that really measured ~2x4 instead of 1.5x3.5 is a better guess. But again, if that's the reason, the installer should have explained it that way, not blaming the previous installation. I guess that assumes the installer even knew what he was looking at.

[Ferd Farkel]

I generally use quarter round or shoe molding, caulked in to blend everything together and make painting neater.

[Edwin Pawlowski]

Not necessarily.

Many years ago I had a sideline business selling and installing replacement windows. These were pre-made units that slipped in where the old sashes were. There is a stop on the outside for the old sash. We just ran a bead of caulk and put the new unit in place against it, drove a few screws, put the trim back and it was done. If, for some reason, the sash was thicker than normal, there would be a gap at the sill. There was, normally, no reason to touch the sill. If there was a gap, we carried some prepainted wood trim to put in place.

At the time, we were paying $35 for a window unit and charging $55 installed. That was $20 every half hour! Big bucks in the 1960's.

[Bill]

I've seen 2x4's go from 3-3/4x1-3/4 to 3-1/2x1-1/2 and lived in a

1920's farmhouse where the 2x4's measured 2"x4".

Many (if not most or all) of the modern clad windows are thinner than the pure wood frame windows.

I'm sure that any of the above differences could have caused the problem.

Bill

[Hoosierpopi]

I've got to side witht he fellow who asked for a PICTURE.

But, then, the prices involved are likely rectilinear when first constructed. So, don't worry about filling the gap with pieces that match the gap, but that match one of the existing bits (Sil or whatever), then, putty/seal the remaining cap.

THere's a product called Water Putty - forget - but it comes in a red and whilte (and maybe a little yellow) cardboard "can." You mix it with water and you get ROCK HARD (water) PUTTY. It does shrink some - but it does dry hard and faxt. It is "sand able" and (relatively) cheap.

[e-mail] "will withstand weather if kept painted" "Durham's is meant to fill voids"

[George]

So, don't worry about filling the gap with pieces that

Did your windowmoron install flashing to redirect the water at the top to the ground rather than the gap?

If not, that's your first order of business. Under the siding or whatever forms the skin of the house, then at a slant past the gap and window top. Commercial products are available.

If the windows are secure in their openings, I'd hit the gaps elsewhere with the low-expansion poly foam aerosols, trim, and caulk with latex. The Durham's isn't flexible enough, though a wonderful product I've used for years in woodworking.

[DerbyDad03]

FYI...the OP posted the same question in a.h.r, Nor cross-posted, so replies here and there, don't show up there and here. This was my reply in a.h.r, based on my recent window replacement project:

If I understand your question correctly, I had the same problem when I replaced my windows. It doesn't mean that the old windows weren't installed correctly, it means that the new windows are "thinner" than the old ones, say 3.25 inches deep instead of 3.5. When the new windows are pushed back against the exterior stops, an interior gap is the result.

As Dan suggested - backer rod and caulk will solve the problem. See this site for info on backer rod:

Don't try the borgs to purchase - none of my local home centers carried it nor did anyone in the paint/caulk department know what it was. I went to a contractor supply house and paid between .05 and .

065 per foot depending on the thickness. The supply houses sell it in bulk by the foot as opposed to packaged in pre-cut lengths. It's much cheaper than way. I used 1/4" or 3/8" around all 4 sides of my windows before caulking the interior. There'e really no good way to caulk deep gaps without it...that's what it's made for.

My concern is that if the contractor did not seal the inside of the window along the sill, what else didn't he do? By sealing both the exterior and interior edges of the entire window, you create the desired dead air space.

[Ferd Farkel]

Measure the window right?