If you are remodeling your home, you can save a lot if you will repair plaster walls instead of removing whole panels. Most drywall that is old has various small holes in it from a variety of causes. These can easily be patched up and repaired, although cracks are more difficult to remedy since they usually go all the way through to the surface beneath. In patching up your plaster walls you need to get hold of some materials from your local hardware store but the task itself can be done by yourself.
Step 1 - Removing Damaged Plaster
The first thing you have to do in repairing and patching up your plaster wall is to take out damaged and cracked plaster. You can use a small putty knife to test for damage and cracks on the entire plaster wall surface. Alternatively, you can use your hands if you do not have a putty knife. If you find an area where the plaster is cracked or crumbled, remove the portion carefully all the way to the brick wall or lath. When using a putty knife, ensure that you do not accidentally remove good plaster as well.
Step 2 - Assessing the Damaged Area
Remove all the small debris and dust on the area first with a shop vac before assessing the damaged area of the plaster wall. If it is a few feet in height or width and more than ½ inch deep, you can use the drywall as a base. Attach it to the brick behind the plaster with screws or plastic nails. The drywall should be around an 1/8 inch thinner than the depth of the plaster hole. You can make it the same size as the hole since you will be filling it up with a patch anyway.
Step 3 - Patching the Hole
You are now ready to patch the plaster hole. Wet its surface slightly with water. You can use a cloth or spray bottle for this. Mix your plaster patch in a masons pan or small bucket. Apply it into the plaster holes using a putty knife to drive the patch deeper into each hole. If it is an extremely large hole, you can apply the patch in several layers that are less than 1/2 inch thick. To avoid having a patch that is thicker than the plaster wall, smooth every patch down with the putty knife.
Step 4 - Mudding the Wall
Once the patch has sufficiently dried, smooth it over with a 25 minute drywall mud. Apply it over any patches that are not flushed with the wall. You can also apply it over blemishes and small cracks that you can find. The mud dries out fast so prepare only what you can use for a few plaster holes. Smooth it with a sanding block after it has dried.
Step 5 - Smoothing Remaining Blemishes and Gaps
To make sure that you have an even wall, fill up any remaining flaws and gaps with a thin drywall mud. You should use a slow drying compound so you will have to wait a day or two before sanding it with fine grit sandpaper.