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 head scratcher 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
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.
If the window was moved forward horizontally why is there a gap
Why didn't you tell him he left the void and he should fix it?
Take a piece of wood 3/8" or so greater than the distance from sill to
top of gap. Now cut a rabbet in it so that the tongue is just
slightly less than the tallest part of the gap. Cut it to length,
whatever width you want, make it pretty, put plenty of caulk on the
tongue, bottom and rabbet and shove it into gap. Wipe off excess
caulk (you want it to squeeze out).
Bondo or putty is a hack job. Don't even think about it
You have a couple of choices. If I could see it in person or a photo I may
have a better ideal, but here is a couple of suggestions. If I'm reading
this right there is a gap between the sill and window not the sill edge
toward the room.
Replace the sill entirely using a wider piece of wood. If you want to dress
it up, use marble or Corian instead of wood.
Shape the wood to fit. This requires some tools, such as s aw to cut it as
close to the dimension as possible, then use a plane to get the perfect fit.
A small block plane is ideal for that sort of thing.
Another possibility is to fill the void with caulk to seal it, then put a
thin piece of trim over it.
Your mother's windows were a wood common opening. The installer put the
replacement windows against the outside stops, so they wouldn't have to
cap off the exterior. In doing so, you see the results on the interior.
The installer should have trimmed out the interior with 1/4 round.
The other option was to install against the inside stops, and cap off
the exterior with aluminum. This is the preferred method, especially if
the inside woodwork is stained, and not painted.
It appears, your installer did not want to complete the job for a nice
appearance. This is done often, by bidding a job low to get the
installation. But, you get a half-assed job. Sometimes, it's just to cut
corners, and put more profit into the job. Other times, some just don't
know how to do the job right.
Check your contract, to see exactly what was included with the installation.
What are the new windows made of? uPVC/ Aluminium! Seems to me that this
was an unprofessional job, though I speak from the other side of The
Pond, so contract conditions could be different. If the frames are
timber, do you have enough space to put what we call quadrant beading
between the cill and the window frame? I guess you should have.
Two choices that I see:
Insert backer rod to control the depth of caulk and prevent 3
sided bond. Use a good grade of caulk. I would use polyurethane,
NOT silicone. Use good painter's latex if you plan to paint.
Use some trim. Choices, at a real lumber yard: lattice, 1/4
round, base shoe, door stop. If the trim has a shape, it will
need to be coped or mitered. Lattice trim could be square cut.
This will need paint. There are prefinished non-wood trims that
are quite easy to work and install.
Keep the whole world singing . . . .
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
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.
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