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Plaster Bulges and Cracks -- Help.

10807 Views 5 Replies 5 Participants Last post by  12penny
Greetings. I just found this forum, and I'm hoping I can get some help with my plaster problems.

My house is 130 years old. The walls are plaster over lathing. I've noticed in a lot of interior walls the development of very fine cracks in the plaster. They look as if someone drew thin pencil lines. Some of these have started to form actual cracks. (Photo 1) Most are on stairway walls. In one areas, I've developed a long "bulge" in the plaster (photo 2). The bulge is still firm, however. If I press it, it doesn't flex back to the lathing. There seems to be a thin crack forming along the ridge of the bulge.

In other areas, such as a back stairway, which is not heated, the cracks are very bad. (Photo 3).

Any ideas what causes the cracking? My house is not well-insulated, and it's a weekend house. During the summers, it gets up to 80 or so and in the winters down to 55* (except on those rare power out occasions, when it freezes).

I'm especially curious about the bulge. My contracto has no idea what caused it.

I want to do some painting, but I think I need to address these cracks first. Any ideas would be greatly appreciated.


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Here are two more photos. One of the "bulge" and another of a bad plaster crack. There seems to be some drywall tape along the ridge of the bulge.

Someone told me about Big Wally's Plaster Magic. I saw someone had a positive review about it. Would that help me here?

(Sorry, I did the photo upload incorrectly. I'll try to fix them)


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There is really not much to worry about it. The wall has served its purpose for a long time. It is just plaster separating from the lathe.
Ceiling is another matter because large chunk can fall. Easiest in that case is to cover the entire ceiling with 1/2" sheetrock. Mud ring for the electrical boxes. In fact, soon as possible for the ceiling.
If you must repair, search the net and the youtube for plaster repair. Repair depends on how well your plaster is locked to the lathe in general, but it looks like it is time to remove and reboard. Wallpaper, mesh sheets, glue and screw, all depends on your plaster.
It might also be worth considering what else might be moving that would lead to the cracking. Is something settling down below? Has something else shifted? Plaster is pretty rigid and generally isn't going to crack unless something else causes it to move. So, before you go repairing this it'd be worth figuring out if something else is to blame.
The "bulge" is firm because the plaster has moved forcing the crack shut tight. You need to make sure the plaster is firmly attached to the lath/framing or it will open-up after your fix, later. Here is a unique way to adhere the plaster; Need more finishing than shown, maybe even paper tape/setting type compound over the crack rather than just filling it after gouging with a screwdriver or can opener.

I've had success with "plaster buttons". I'll run them along the crack on both sides then tape and spackle. I suppose on smaller cracks they could be installed on the crack.
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