"Scott Mathers" wrote in message
...
I am thinking of adding insulation to our attached garage wall, to increase
the insulation between the living space. Is adding Dow styrofoam board or
something similar a good idea, or worth the cost?
(It's more flammable than the 5/8 fireshield)

For example, the Dow 1" stryofoam board would add R5 to my wall, which is
only 3.5" with R-11 fiberglass.

Thanks guys!

If when you stand in the house near that wall, you feel colder than another
exterior wall or if the wall feels cold to the touch, it may be worth it.
One cannot give an objective answer to the question as posed. Going from
R-11 to R16 seems like a small step but if the wall is cold, it may make the
difference you want.

If you are just looking for ways to randomly cut your energy budget, you
want to more carefully consider the costs. At best you will see less than
10% savings over total. Making up optimistic numbers: Lets say your
heating bill is $200 per month in the winter (5 months) and you save 5% by
installing the insulation that comes to $10 per month or $50 per year. How
much is that insulation going to cost you?

If you are trying to improve the comfort in a certain part of your house, it
will be worth the cost even if the payback is long.