Tony Hwang wrote:
mtco wrote:

What is the best way to find out the type and amount of insulation
installed inside an exterior wall? By "best" I mean minimum effort and
the least likelihood of the attempt turning into a big repair job.

The wall in question has drywall on the inside and vinyl sidings on
the outside.

Thanks in advance.
Hi,
Where do you live? This is first thing to consider. The location.

Actually, it doesn't matter where he lives. He is trying to minimize
the heat flow out of his house without major rebuilding.

I'm looking for a good answer to the same problem. Sometimes I install
a slider or something that requires ripping apart a wall from the
outside. I just put in insulation at that point. In 1970 they used 3"
bats so it's not hard to justify ripping that out and using current pink
stuff bats.

I thought sprayed-in foam as seen on This Old House might be an option.
I eventually wound up talking to the company (in Canada) that makes
the isocyanate foam. They very clearly recommended against their
product! The problem is it expands and will push off the interior wall
board. This is the $0 solution.

I talked to a contractor about installing blown in cellulose (i.e.,
newspaper shreds). He wanted to add several inches over the ceiling
insulation which already has 6" of pink stuff bats and added fluff.
And, blowing cellulose into the walls involves drilling ugly holes that
have to be hidden. This was the $1700 solution.

I used an infrared remote-reading thermometer to figure out that my old
slider was a major heat lost. 8' slider, Al frame, single pane.
Typical readings: 25 deg outside, 75 inside, window was 45 on the inside
even with the plastic film "storm windows" on the inside and the
outside. I had the slider replaced with an Anderson. $2200 solution.

As it gets colder I can also sense that the new slider is keeping the
place warmer. And, added bonus, it is quieter.