My GF lives in a house with a very steeply-pitched roof. The second
floor looks like this:

/\
/ \
/ \
/ \
/ \
/ \
/____________\
/| |\
/ | | \
/ | | \
/ | | \
/ |living space| \
/ | | \
/attic | |attic \
/ space | |space \



The second floor is hot as hell in summer and cold as hell in winter. I
checked and found that there is *no* insulation between the 'attic
space' and the 'living space'. Would it be a good idea to put
foil-backed insulation on the outside of the living space walls? I just
happen to have a quantity of it that I'm not using.