Here’s how I fixed the cracks in the ceiling and walls of our living room:

ceiling crack
Here’s the crack in the ceiling. It actually runs the whole length of the room (essentially cutting the ceiling in half).

The first step I took was to widen the crack. Yes, you actually have to make it worse before it can get better (this seems to happen a lot in home renovation, whether you want it to or not).

ceiling crack scar
Now the crack looks like a big scar.

cracks in the wall
Here’s a whole bunch of cracks in the living room wall.

I have old horsehair-plaster and lath walls and ceiling. The stuff is nasty when it crumbles. In order to prevent the ceiling from moving/shifting in the future, one option is to remove a larger chunk of plaster.  That way, fresh plaster can be pressed into the lath and “keys” can form on the other side. I did not want to go that route. Instead, I used plaster washers and drywall screws (see picture) to “reattach” the loose plaster ceiling to the wooden laths. I know that plaster enthusiasts and purists will hate me for this, but I want to go the easy route. Plaster washers are also known as perforated ceiling washers (and can be found in the screw/nail section of home depot).

plaster washers, screws, mesh tape
The essentials: drywall screws, plaster washers, fiberglass mesh tape

Next, I screwed the washers along both sides of the crack. Tip: If you screw in a washer and miss a lath, you can either take it out, or leave it in. But then screw another one about an inch away (diagonolly). Hopefully that one will hit a lath. Place enough washers in until the wall does not give when pushed on.

Then I place fiberglass mesh tape over the length of the crack.

plaster washers and mesh tape over crack
Plaster washers and fiberglass mesh tape on ceiling crack

Next comes joint compound. There are many types to choose from, but I usually start with the easy sand 90-minute setting compound. This comes in powder form and needs to be mixed with water. By now I have enough experience that I can comfortably use the 45-minute set time variety, but I’m still using up my old 90 minute bag. After it’s mixed with water to the right consistency, I apply it liberally to the crack using a 10″ putty knife (the bigger the better). Tip: The less strokes with the knife the better. And don’t worry too much about holes or air pockets. They’ll get filled in on the next coat. And remember to feather out the sides.

Starting the first coat

After it’s dried - a few hours with the 90 minute compound - I sanded it (of course, I’m wearing a respirator or dust mask when doing this type of work).

Then I repeat for the second coat.

Second coat applied and sanded

For the final coat, I usually just do a little touching up here and there (filling and sanding). I don’t like to add a whole lot at this point. Also, I use a lightweight all purpose compound, for ease.  It comes ready to use in buckets.

Final coat applied. Just a final light sanding left and then painting.

Priming and painting comes next.

After 1 coat of primer.

After 2 coats of primer (still wet when picture taken).

And with a coat of ceiling paint. Voila!