There are several ways to prevent this. One is to prick the crust, then
fill it with dried beans, or pie beads, which are made from ceramic.
There is also a chain of beans (google for cooks catalogs) that you can
place at the bottom to keep the crust from puffing up and shrinking.
The problem can start sooner than that. When putting the dough into the
plate, it can't be stretched or it will shrink. It's difficult to
explain, but easy to deal with.
Drape the dough over the plate and lift the edges to lower the center
into the plate rather than pressing it down. Press (very gently) the
dough out from the center while lifting the edges and feeding in however
much dough is needed to make it fit. When you get to the bottom of the
slope, lift the edges and very gently push the dough down into the
plate, rather than stretching it out from the center. Do that all the
way around. Trim and decorate to suit yourself.
Ahhh.... Now THAT'S what I was looking for. I learned to weigh the
crust down to prevent "puffing" a long time ago. The sides continue to
shrink down (usually unevenly) despite weights. I am always very
careful to avoid stretching the dough but some may be unavoidable. How
do you recommend fitting it into fridge? Folded?