Cutting Plaster with Metal Lath

I'm preparing to replace a section of badly water damaged ceiling in my daughter's home. It's plaster over metal screen lath. My working plan is to cut out a 4' x 6' section and replace it with sheetrock. I'm looking for advice on how to most efficiently cut out the old work with a minimum of dust. I was thinking maybe to first cut through the plaster with a diamond blade on an oscillating tool and then cut the metal out with a 4" thin metal disc on a grinder...or will the diamond blade go through that, too? Your experience/ideas appreciated. Thanks in advance.

you have a mess on your hands .
I opened up several doorways in a condo to make it handi cap accessible. it was plaster on metal lath
I used metal cutting blades in angle griner & circular saw. but it was a huge mess.
the unit was empty so it wasn't a big deal to clean up.
I have learned since then that plaster often has asbestos in it too,
maybe consider going over the entire ceiling with drywall?

I did this for a recent kitchen remodel when I turned a full wall into a half wall. I used an oscillating tool with a fine tooth metal cutting blade will cut through the plaster and metal. Hold a shop vac however right next to where you are cutting and it will pull in almost all of the dirt and dust. It's a slow process, but it works really well. Grinder and saws throw the dust everywhere.

You'll be forever. I was the building engineer for a high rise condo building built in 1961, Lots of plaster work in other people's homes.
Use a sawzall with a metal (fine'ish) blade on it. If you have a helper, have them hold a shop vac. It'll be less dust and much less time. Makes a decently clean cut and use a short blade with the gaurd pressed firmly against the ceiling so you don't rattle the rest down

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No matter what you try, it will be a 2 person job.
There is no way you want to do it without a shop vac held right at the cut point.

Sawzall with and yes with a wood cutting blade. Metal blades just took me too long..

sixty4 said:

Sawzall with and yes with a wood cutting blade. Metal blades just took me too long..

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Agree with sixty4, use to run into this all the time in contracting. The ruff wood blade work fast, not so much by cutting the metal mesh but by catching it in the teeth and breaking it. Metal blade are very slow

Thanks for all of the responses! Thankfully, there's no asbestos. I have all of the gear mentioned in your posts & I'll be tearing into it later in the week. I'll post up the progress and results. Best to all!

My house is plaster over metal lath. I use a carbide tipped demolition blade in my oscillating tool, with a vacuum near the cut to keep the dust down to install electrical boxes. But I couldn't imagine doing that on a large scale.

Real plastic is surprisingly water resistant. And the mortar like layer embedded in the lath may be waterproof. I've had maybe a dozen square feet or so I've had to repair, and it is totally not worth cutting out and rocking over. Learn to do the repair in the original manner.

1) Fill in the deep missing sections in perlite base plaster:
https://www.homedepot.com/p/USG-50-lb-Structo-Lite-Basecoat-Plaster-163841040/202329666

2) Top with a setting plaster. I suggest the 45 if you work fast, but there's also 60 and 90:
https://www.homedepot.com/p/USG-She...-Setting-Type-Joint-Compound-384210/100321610

It's been many years but I recall using a flat bar (normally used for pulling nails) and beat it through to cut the plaster and wire mesh. (Cut right down the middle of the studs). I used an old wood chisel where I needed a cleaner edge.
Actually this is the same technique I used for Plaster and wood lath.

A new fangled SDS plus drill, set to hammer only with a 1" wide blade. Anything that spins will make too much dust. Anything that reciprocates will be much slower. The SDS set on hammer mode lets you cut perfect lines. Bought my bosch to remove a bunch of tile. Have now used it to drill too. I drilled a bunch of 2 1/2" holes with the hollow core bits they sell. those are dusty, but they fuckin' work!

If the leak is fixed, why not just drywall over the complete ceiling with lightweight drywall?

Posting up with results -- all positive. First, again thanks for all the posts and collective experience & wisdom. The plumber appears to have used a hammer to bust out an area below the leak, leaving an irregular opening. The thickness of the plaster is 3/4" which was to be replaced with 1/2" green drywall. I squared up an opening 3' by 4' using an oscillating tool. I tried a 3-1/2" semi-circular diamond blade first, which worked but pretty slow when it met the metal mesh. I changed to a titanium coated bimetal flat blade; that was the ticket. Particularly where the plaster was tightly secured to a joist, it blazed right along. It was a little slower in areas where it wasn't. I only manage to rattle loose a small amount of finish coat along places along the margins in a few places. I cut along the inside of the joists rather than the center to leave the plaster secure, and sistered in sections of 2x4s for nailers, which I lowered 1/4" so that the installed section of drywall would match the surface level. I followed the advice of keeping the snout of a shop-vac close to the tool, and it really minimized the dust and I had the area isolated with plastic drop cloths taped in place around the doorways and stairway. So, all that's left is to tape and mud. Thanks again for all the help & Best to everyone.