Water can be very difficult to finish plaster.
From ugly stains to peeling paint hanging from ceilings, you have a bigger problem of aesthetics alone.
Yes, the obvious first step is to find the source of water intrusion and fix. Only then does not make sense to continue with the repair of plaster.
In my experience, there are several common sources of leaks.
Plumbing leaks. If you can not fix plumbing, six ahead of the game. Otherwise, bring aprofessionally and do it well. This can lead to a hole or a series of holes in the plaster. It may be disappointing, but not so difficult to repair.
Roof leaks. There is almost an old house that has not been visited by this accident, one or more times. Normally the ceiling where the damage to show. If you're lucky, you just have a few points or a little 'paint peeling done. But you can also create a bigger problem, like pronounced sagging.
Watercome through the walls. When a wall is masonry, like stone or brick, it may happen that the water wick through the wall and the coat of plaster inside. In order to get bubbles spray paint and plaster, maybe even relaxing some of the veneer coat (outermost layer of plaster).
Sometimes the root of the problem is faulty gutters spill water on the wall. On wood framed walls, water leaking around windows sometimes appear as dots,peeling, etc.
Now, on drugs.
First, as a "do yourselfer, you can get a good job of repairing plaster with gypsum and gypsum composite bands do. If you do it right and you are properly covered with water sources, plaster repair will last. Really should not be necessary to repair plaster cast.
You can use all the mud plaster purpose, or "hot mud", a substance that type of approach is more difficult than ordinary mud.With hot mud, mix small batches. After completing step one, the tools clean and pan carefully before you make a lot of new blends.
City and peeling paint is easy to correct. Scraper or wire brush the surface, and then erase with a sponge or a damp cloth. You must remove all the dust and scale of material. Thouroughly Once it has dried, paint on a stainkiller to close in the village and has a hard surface for the mixture to continue to give.
Card application of plaster of each band,cracks and give them two consecutive layers, at a minimum.
Larger holes require support. If there is no room for the confirmation of a patch, you should sit in the background. 1 x 4 boards or plywood strips can be screwed and screwed thin plaster. Shim, if necessary, the first so that the plaster is flush with the surrounding plaster. Fill around the edges of hot mud and tape the whole perimeter. Skim pages prisoners coat until the entire cake.
If the plaster is bending, itwas to remove and thin with chalk, as described above, to be replaced. More than a plank of wood, is relatively easy. If your plaster is the kind of style of plasterboard, and over coat veneer is crumbling, bent as seen from the ground and replaced with plaster, etc.
On the external walls of masonry, until the water problem through a thorough cleaning, then use a special sealant to be solved. It might be good to consult a professional. Replacing defective gutters.Then inside, scrape all loose / powdered chalk. Clean the depression, etc. powder diluted and filled with one or more layers of boiling mud, if necessary.
If you can not repair the damaged plaster yourself, you have the valuable experience and save money in the process. And … You admire your work!