On Mar 30, 9:12*am, John Ross wrote:
I'm having a window replaced with a vinyl replacement window. So the
frame of the current window (steel) will be left and the new one has a
lip on the outside that goes beyond the window to the stucco.

I still have to confirm this, but it appears that the company does not
fill in the small gaps from the undersized replacement to the old
frame with any insulation. They caulk the outside fin and then the
inside trim.

Any opinions on if it is important to put some sort of insulation? One
thing I realized was that there would be the vinyl and then about 3
inches of space then the trim vinyl sealing the other side. It
occurred to me that the *glass* only has air in between it too, and a
much smaller gap.

Actually, I am more concerned about noise than anything, and I seem to
recall people in here saying fiberglass insulation does little if
anything for noise.

Is this an issue in the install that I should even be concerned about?

--
John

If the window is caulked correctly, inside and out, this will create a
dead air space, which is a great insulator. That said, many
installation instructions say to use fiberglass insulation or low-
expansion foam in any gap wider that 1/8" and then caulk the seams.
If you use insulation, you don't pack it tight because it losses R
value.

Another thing to ask the installers about is backer rod. If there is
nothing in the gap behind the caulk, it is very difficult to get a
good 3 sided seal. Backer rod is a round foam strip that get's stuffed
in the gap to - ready? - back up the caulk. The wider the gap
(sideways, not deep) the more important the backer rod is. Try
caulking a 1/4" gap with a 3" void behind it - you get the idea.
Backer rod comes in various widths for various gaps sizes and is
pretty cheap, like a nickel a foot in bulk.

Remember that once they reinstall the trim, you won't know how good a
caulk job they did, so I'd make sure you get a good explanation as to
how they are sealing the gap. You can spend thousands on a window job
and be worse off than when you started if they do a lousy job of
installing them.

Good luck!