talley sue, I have more experience than I want with compromised plaster ceilings. You're right to be concerned about loosening the rest of the plaster when they take down the damaged part but you might be good with the route you're going.

I tried several different approaches. Two very small bedrooms were so bad - entirely loose - that I took the whole thing down to the joists and put up sheetrock. Very messy. I had some water damaged ceilings in a hall initally repaired 20+ years ago by a 80+ year old plasterer, but not with the bonding and mesh you describe. Mine are plaster on wood lathe and the loose sections came off without much effort. There was some subsequent cracking where the patch met the original plaster but it took a few years to be obvious. About 15 years later I installed the mother of all skylights and so took down the entire hall ceiling - it wasn't worth the effort to try to reframe the ceiling and work around old plaster.

Two other large rooms (my bedroom actually dropped a section of plaster while I was dressing for work one morning) and two other halls I had laminated with sheetrock. They were completely covered with 1/4" sheetrock, screwed very frequently into the joists, taped and then skim coated. The old plaster is not removed; the sheetrock/screws holds it all together. I liked the approach because it didn't involve any specialized materials/methods (I'm not familiar with bonding/mesh) and it was the least messy. I did the laminated ceilings between 1991 and 1995. One developed an inexplicable hairline crack a year later that was skimmed with the next paint job and never returned. A hall developed a hairline crack near the staircase opening in the same section that had been repaired several times going back at least to the 1930's - I'll bet there's a cracked joist under it.

So bottom line, after that long story is that I had good results and nice ceilings with the laminating method. I checked his references carefully - I saw several homes and talked to the owners where he had done the same work. I have detailed plaster perimeter molding that I did not want disturbed and it wasn't. I lost the first 1/4" high ridge of molding (height of the sheetrock) but I subsequently replaced it with a very similiar wood profile and you can't tell the difference - nobody noticed but me to begin with. My neighbors had one of their ceilings replastered from scratch and I can't begin to guess what they paid but it was huge.

I wonder if using plaster washers would help? If you put them in the area that is to remain. You're going to skim coat over it anyway so you wouldn't se them.

thanks for the input--very useful.

I think I'll discuss this worry w/ my plaster guy, and see what he says. he didn't raise it as a worry.

I think the ceiling is basically very solid, so it's not as though the entire ceiling is slowly giving way. And it is only the water damage that ever caused it to separate. That may be why he's not worried, because he'll be removing parts that are already loose, and so thinks he won't shake the rest of the ceiling much.

Neither of the two guys I spoke w/ actually talked about the laminating method--the other person w/ the drywall plans said he'd take the whole ceiling down. We did apply a sheetrock ceiling over the plaster one in the kitchen, but the contractor put up new 2x4s--he put them w/ the long side pointing down, and it REALLY dropped the ceiling; after i pointed it out, he decided to turn them, But I'm still not really happy w/ that, the ceiling is still noticeably lower than the other rooms, and tehre's not much space above the window below the ceilig.

And I do NOT want a similar effect in my bedroom! So perhaps that's why I didn't think of it. I wonder if someone could just lay the drywall against the ceiling, or use much thinner furring strips. I'm not sure what the joists are like above my head.

Jude, is your "laminating" guy still in business?

(the quote for the plasterer, who'd remove only part of the ceiling, replace w/ plaster, and skim coat the whole thing, is less than $2,000 for a 13x14 room)

think I'll discuss this worry w/ my plaster guy, and see what he says. he didn't raise it as a worry.

I think you should trust this guy's judgment,afterall he has probably seen countless situations such as this and more than likely will give you some kind of guarantee as too the ceiling falling down.Real plaster guys are becoming extinct,so trust him and let him do what he does.

Talley Sue- we have an old house too, My DH has put sheet rock up over the old plaster, and it will hold for years if done right. The loose lath and plaster need to removed. It is possible to even put in a patch of sheetrock in the hole, and skim coat it and paint and voila! Our 14x 26 living room ceiling has several patches in it- done in the early 80s - can't see them.In short the whole ceiling doesnt have to be ripped out to sheetrock it- unless it is all loose. You can't tell the difference between the orginal and the sheetrock- except for the lack of cracks! one bedroom was sheetrocked over by DH 20 years ago. looks great. HTH Sue

What type of plater?
2 layers with gyp backer or 3 layers over wood or metal lath?
The plaster is not really held up by nails so much as either keying (wood or metal lath) or adhesion (gyp lath).
If the plaster is actually failing it shold not tqake much to get it down the rest of the way. i routinely strip with a wonder bar until the plaster gets solid enough to take som ereal prying to remove. Add plaster washers back from the edge and then replace the missing material.

Replacement can be done with gyp board as a filler and either Durabond or Easysand. Durabiond is closer ot plaster in hardenss, but like plaster cannot be effectively sanded.

I'm thinking 3 layers over metal lath. Most of the ceiling isn't failing at all--just a big section by the window in the front.

Plaster washers sounds like a good idea--and it sounds as though you think the remaining ceiling will be sound enough?

Plaster washers do not owrk well in metal lath.
Ter is nothing for the screws to grab onto in the metal mesh.
If the damage is in a localized area check for moisture intrusion first. Being near a window is another signof possible moisture problems.
Check head flashing above the window, and the general condition of any joints around the window in the siding.
Masonry houses have a special set of problems.

If you are sure no moisture is still entering, consider Durabond for a repairs.
Remove any damaged plaster, and then use Durabond to make the repair.
Mixing with loose fill fiberglass for the first coat, then a second coat with some sand as an extender, followed by a straight coat for the finished surface.

it's defnitely water damage

The co-op apartment building's facade was open bcs we were replacing the lintels and bricks; the workers hadn't tarped particularly well that day; and then we got a massive rain storm w/ tremendous wind.

They've finished the facade work; there's no more moisture intruding (I had mentioned that in my initial post).

Good know know about the plaster washers and metal lathe. I e-mailed the plaster guy; he said that because the loose section is SO loose, removing it won't really jostle the rest of the ceiling.

I don't know whether the plaster guy will do 3 coats or not--I'm assuming yes, though I think he's planning a single day. How long will the coats need to dry before the next one is put on?

Plaster dries pretty fast, or should I say "sets up" pretty fast, because it is a chemical reaction, sort of like concrete. I'm pretty sure he should be able to do all three coats in one day.

I think you made the right call. An experienced plasterer can tell just where the moisture damage ends - it will become significantly more difficult to peel it off where the sound plaster starts. There shouldn't be much "shaking around" required to remove the damaged stuff, so damage to the solid portion is unlikely.

Odds are, the guy who wanted to remove the entire ceiling was just more comfortable with drywall work than with plastering. It sure seems like a waste to bring down sound plaster when not necessary.

I have never heard of that mesh idea, but it sounds like a good one to reduce or eliminate plaster's biggest drawback: cracks.

thanks, tryinbrian! That's reassuring to hear.

I agree w/ you on the drywall guy, and on the idea that it's a shame to bring down sound plaster when you don't need to.

One thing I have learned, esp. in home repair, etc.--don't mess with it more than you have to!