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