Suggestions for Plaster Repair?
I recently purchased a 1920's home in central Massachusetts and am getting to work on renovating. One of my first projects was to redo an upstairs bedroom that had some badly peeling wallpaper. After stripping off the wallpaper (which took all of 15 minutes with no tools, very poorly applied), I was left with a very rough plaster surface which seemed sound, if not the most attractive texture. I decided to try my hand at skim coating with finish plaster on one of the walls to smooth it out. That went fairly well so I made the decision to go ahead and start removing molding to do a proper job the of the whole room. Here comes my problem. I got the lower molding off of one of the windows to discover that the plaster was not at all adhered to the lath behind. There's a good 1/8" gap between. The edge of the plaster under the sill was dry and crumbling to boot. Some experimental pushes against the walls in other parts of the room seem to indicate that I may have the same issue throughout the room.
So, obviously I need to deal with the crumbling plaster underneath the window, but I'm wondering how much of an issue the potentially separated, but still intact plaster is in the rest of the room. I hate to tear out perfectly good walls if it's not entirely necessary. Anyone out there have any advice?