New York City Homeowner's Guide -
Attics are sometimes overlooked as storage space, especially if they
are difficult to access. Often simply putting in a better staircase
to the attic or moving the staircase to a more convenient location (e.g.,
from the center of the attic to a corner or wall) encourages use of
the attic. If the attic floor is weak, additional floor joists can be
added to insure sufficient floor support. Then, like basements, elaborate
storage centers can easily be created.