Plaster ceilings (and walls)are always worth saving. Often they were covered up by well meaning people who didn't have access to any repair information. As you noted your sheetrock ceiling fell down. Plaster from the 18th century through to the early 1920's was made from lime. Lime plaster while it may get heavy from water leaking on it, when it dries out it will be as good as ever. Sheetrock will just fall down when wet. Original plaster by virtue of it still being in place and not falling down makes it a great surface to restore. Anything you replace your original plaster will be inferior in quality. Try reading http://www.thisoldhouse.com/toh/knowhow/repair/article/0,16417,1628100,00.html
Thank you, Plaster Maestro. I took your advice and checked out the web site you gave me.
In the meantime, however, here is how I am progressing. As I was pulling down the sheet rock ceiling a huge chunk of the plaster ceiling fell on my head. No stitches needed, but I now wear a hard hat along with goggles and a breathing mask. That area is too large for a novice like me to even consider attempting to fill in with plaster. The fallen plaster ceiling revealed a lathe ceiling. I have halted my work as I am contemplating what to do next.
I know I have to pull down all the moldy sheet rock. Do I pull down all of the plaster and then cover up the lathe with sheet rock?
Anyone out there who could advise me? I have photos of the ceiling I can share.
I would be happy to review your photos. The original plaster cannot be replaced with anything as good or better. Save it if possible. Before I could pass judgment on replacement I would have to know how much is in need of replacement.
Where can I send the photos? I haven't seen a place on TOH to post photos.
Remove the plaster with a crowbar, a ladder, safety glasses. Big mess, throw it out the window where the rain will wash it away. Moisture destroys plaster. Underneath you will find lathing. Replace the plaster with lightweight material of your choice that does not contain paper, sheetrock, or plaster unless you want on ongoing problem. Plaster ceilings are dangerous, and don't let anyone tell you differently. A newbie to the site, I wrote a long explanation that did not allow me to post. Have replaced 7 plaster ceilings myself. Walls are another story.
Plaster ceilings are attached to the lathing. When cracks are throughout, it is a matter of time until the heavy pieces fall. Poke it with a broom handle, and some of it will drop. If your attic has no subfloor, it is a good idea to drop roll insulation in the attic, paper side down (for the insulation) and screw up patterned tin, or a myriad of other choices, including 1/4" plywood to the lathing that could be refinished in a material of choice. Not in the mood to hire a plasterer (dying profession) every few years, but you can keep the aesthtic integrity of your home by using newer, safer and easier to use materials. Owner of a 12 room old house, I did it myself, and it works!
I have to disagree with you. Neglect and lack of maintenance is what destroys plaster not a defect in material. My 1860 home still has the original plaster ceilings even though the house was not in that good a shape when we bought it. Plaster holds up 100 times better in water leaks than drywall. Just about any material will fail if not maintained properly even tin or plywood ceilings.
Water damage can occur from broken plumbing pipes, leaky roofs, hurricane water damage, open windows in a storm, etc. Also, the plaster mixtures vary in old homes, and the skill of the tradesmen who originally installed the ceilings and created the mixes are varied. You must be really old if you are sure that your ceiling hasn't been replastered since 1890. Unless one wants to restore a home to the original for a grant to be listed on historical homes, the newer materials work much better, easier to install, can be made to look like the original, and if they fall, do not pose a threat to life and limb. Also, if the lathing is left intact, (or new lathing could be put up) the ceiling can be replastered if the homeowner chooses at a later date. Appreciating your dedication to a time worn philosophy of everything older is better, I disagree with you on this point.
At least I could disagree with you without being an authoritative smart A**.
If I may wade in on this...Whatever you replace your plaster with is inferior. There is no other fact you need to know. If your plaster (which has a track record of over 12,000 years--maybe not yours)is still up it can be fixed cost effectively. Plaster installed before the 1920's is generally a lime sand hair mixture. This material can get wet and dry out and still be in great shape. So unless you wish the value of your real estate to go down, keep your plaster.