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I cut a piece of the ceiling out in my (small) closet for electrical work. Since I was already at it, I installed a box for a closet light as well.

This shows the closet ceiling with the hole with 0.5% magnification from bottom upwards (this is to show dimensions and layout):

enter image description here

I installed a ceiling metal box onto a beam with a piece of wood as a spacer. Screwing this in was non-trivial but worked eventually. Once I was done, I cut lath (from the original hold piece) in proper pieces, pre-drilled holes and fixed them to the existing lath with drywall screws. Looks like this:

enter image description here

I have never patched lath & plaster before and I do not have a good hand for this type of work. Fortunately the hole is (deliberately) in the closet so things don't matter too much.

How do I best plaster this hole in a most straight-forward way, as possible?

Which plaster should I get? I read about "Plaster Magic" but this seems like an exotic thing that is not available at my Big Box stores (e.g. Home Depot) and I can only order it and it is super expensive and then adding shipping on top of it. Really feels like overkill for such a small hole and one-time work.

Is there a "no frills" way with ingredients that I can get from Big Box stores and hopefully exist in smaller packages?

I do have a box of "Plaster of Paris" at home but I have heard this is not the right one for this job. I know it hardens very quickly but if this is the only downside, that would be OK for such a small hole.

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  • If you have never done this before, a confined space, on a ceiling, around an electrical box is diving head first into the deep end. At least nobody will look at the results. :) But seriously, it might be easier if you FIRST find an inconspicuous spot in the basement or garage, smash a hole in the wall with a hammer and repair it for practice, then move on to this ceiling. Just use the SAME compound for practice as you will on the ceiling. They will all throw different surprises at you. The total effort will be easier.
    – jay613
    Commented Nov 19, 2023 at 15:41
  • Before you start work, screw the ground wire to the box and/or turn the circuit breaker off. You don't want that whole box to become silently energized by accident while you are working on it.
    – jay613
    Commented Nov 19, 2023 at 15:43

3 Answers 3

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If the depth of the plaster is sufficient (≈15mm), I'd be temped to cut a piece of drywall to size and shape, and screw it in place, then fill gaps and cover with filler.

If it's not deep enough for drywall, then you can probably just add water to powdered filler. You might need to build out a foundation over two or three layers before you're able to make the final finish (and then sand, then paint).

I don't actually see any problem using paster of Paris for this small job. You might want to dampen the adjacent plaster and/or lath edges before applying new filler.

There are also a few areas in your picture where it's not clear if there is anything behind. You probably can still get away with only filler because the ceiling isn't carrying any load. But it makes it more likely that you'll have to build up over several applications.

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  • Unfortunately not thick enough for drywall. Do you have an example link for the “powdered filler”? Is this the same as “setting compound” from @Aloysius Defenestrate ‘s answer?
    – divB
    Commented Nov 23, 2023 at 0:13
  • This is what I've used before: screwfix.com/p/toupret-quick-dry-filler-2kg/763pp. Setting compound is same kind of stuff — quick drying, no shrinkage. Commented Nov 23, 2023 at 22:11
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The truly no-frills technique here is to slap successive layers of ‘setting compound’ (eg setting compound ). They come in various set times — 5, 20, 45, 90 — and in small boxes. You’ll want to build in layers, as even a stiff mix won’t work as a single pass. On the first coat, really try to squish it between the lath, so that it’s well anchored.

This stuff is hard to sand, so don’t heap it on thinking you’ll flatten it later; sneak up on getting it flush with the rest of the ceiling.

If you feel like getting a nice flat sanded finish, use a bucket of premixed all purpose mud for the last coat or two. (Topping mud is better, in that it sands very easily, but doesn’t usually get sold in small quantities in my area.)

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  • Awesome thank you! Can you comment on which setting time I should best choose? Why different ones in the first place? Different layers different setting times?
    – divB
    Commented Nov 23, 2023 at 0:08
  • And for the last layer, is this the same as “general purpose joint compound”? I’d have a bucket of this at home already. Otherwise, do you also have an example link?
    – divB
    Commented Nov 23, 2023 at 0:11
  • Pretty sure that the bucket you have is the right stuff. Forgot to mention that once it’s flat, you can tape the seams and give it a couple of thin coats, but for the ceiling of a closet, I probably wouldn’t. Commented Nov 23, 2023 at 0:44
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@dentarthurdent's first suggestion is how I've repaired lath and plaster holes in my own home; install something to take screws, cut a patch and install with screws, mud or spackle the edges, sand, paint.

Places that sell plasterboard often have broken fragments you can get cheap or free, so you shouldn't need to buy an 8' sheet for a 1' patch.

For the ceiling I was repairing 3/4" plasterboard was a close match, but it might be other thicknesses elsewhere. And of course there will be some variation as with any handcrafters material. But you should be able to get close -- and unlike my case, yours is in a spot fee people will look at, so if it isn't perfect odds are that nobody but you will notice.

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  • Yes, measure before you buy. For walls I've patched, 3/8" was perfect. Just remember that it's a lot easier to add a layer of filler than to cut away a patch that's too thick. And as you said, it doesn't have to be drywall; Masonite with a thin layer of drywall compound over it works great too. Commented Nov 19, 2023 at 15:38
  • I actually have a few drywall sheet at home but I think it’s just not thick enough…
    – divB
    Commented Nov 23, 2023 at 0:14
  • You most likely have 1/2" drywall scraps. 3/4" may be a closer match.
    – keshlam
    Commented Nov 23, 2023 at 4:09

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