Moderator Post (s) for this thread: >Plumbing ChasebyBillhart on 11/30/2008
First you don't have any attic (flat roof) or there is just no access.
You can alway cut in an access panel.
Typically very little wiring is run above the ceiling. Just those to the lights.
But depending on all of the details of the constuction for rewiring they might use something like a plumbing case to pull new branch circuits and then run them across the ceiling and down the wall.
There are all kinds of tricks that electrican use for rewiring.
Get one that is experienced in doing old homes.
Then let then cut what hole are needed for access in the ceiling.