Hi NancyT, I'm restoring a 100 yr. old house too, 105 years to be exact. I had to read a book on insulating our house and found that if you fill your wall with insulation, you must have a vapor barrier and it goes on the warm side. If you do not have a vapor barrier moisture will accumulate in the insulation and rot your structural members. Do you live in a heating climate or a cooling climate? That determines what side the vapor barrier goes on. I had to remove the siding on one side (because it was rotted on the ends (for Brian's info, It had to be replaced)). You should check into icynene foam. It's a water based insulating foam that is also a vapor barrier. It is a liquid that expands in the wall. I had it installed in both the open walls and the one's I did not remove siding on.....all exterior walls. If you decide to go the icynene route (they have a web page) http://icynene.medius.com/main.html ,let me know, I need to give you some things to watch for. My wife calls our project "Habitat for Insanity". Good Luck.