Cutting through lath/plaster

[s_wilwerding]

I'm documented some of the other issues of fixing up my 1905 house on this Board before, but I've got a new one.

None of the bedrooms on my second floor have ceiling fixtures, just wall sconces. I'd like to put ceiling fans in a few of the rooms, and light fixtures in the others. Wiring is not an issue, since I can wire through the attic above (there's even a breaker box in the attic).

The issue I've run into is how do I cut through the plaster/lath to add the switches on the walls and the outlet boxes on the ceilings? The best idea I've heard so far is to use a Rotozip with the plaster bit. Other ideas are to drill holes and connect them using a hacksaw blade.

The main objective it to make a hole as big as I need without chipping out the surrounding plaster.

I'm sure I'm not the first person with this issue, so I'm interested in hearing about the best way to do this.

[TimT]

You can get a carbide grit hole saw that mounts on an arbor. Starret, Vermont American etc make these. However the arbor/hole saw package will probably be around $50-60. I used somethings like this to cut holes in the Stucco of my 1929 house to install some exterior outlets.

Search McMaster Carr, or Grainger

[MikeSid]

The appropriate sized hole saw would make the cleanest most uniform cut.

I typically just use a keyhole saw and do it by hand. The fixture will cover imperfections. The hole doesn't have to be perfect.

But if you do cut the lathe with a saw (power or not) I'd suggest not cutting all the way through the lathe on the first cut. If you do, when you want to cut the other side of the lathe out, it will flop back and forth because you've just freed up one side of it. So leave the first side to cut partially attached. Then just punch it out when the other side is close to through.

[david914]

I use the RotoZip with a carbide bit. Messy as hell, but it does the job with the least amount of chipping. If you get one, be sure and get their circle cutting jig as well. Works like a charm.

My house was built in 1937 and has metal lath/plaster ceiling, with plaster-board/plaster walls.

[RickM]

How about a jig/sabre saw with a metal cutting blade?

[MikeSid]

The vibration from any reciprocating saw will cause havoc with the plaster...particularly once you are through one piece of lathe and it flaps freely with the blade.

I wouldn't over-tool this task. I've done it with a utility knife. Carve a circle, chip out plaster, cut lathe with knife. It's not a bank vault, it's 100 year old plaster.

[Rot 911]

+1 on the Rotozip. I've tried most of the other methods suggested and none work as well on plaster. Most saw blades just get worn down cutting through plaster.

[Burnin' oil]

Rotozip. Keep a sharp bit in it

[HardDrive]

Originally posted by MikeSid
The vibration from any reciprocating saw will cause havoc with the plaster...particularly once you are through one piece of lathe and it flaps freely with the blade.

+1. I have a Milwaukee sawzall. It would do the job, but its damn powerful, and if it go away from you, it could really chew things up. Not to mention it would easily go through floor joists in the ceiling above......

[Dan in Pasadena]

Originally posted by MikeSid
The appropriate sized hole saw would make the cleanest most uniform cut.

Yup, and the rotozip is second, but if you don't have one? I'd drill a hole and use a keyhole saw. If you dull it? Who cares, they;re cheap. CUtting through plater just isn't like cutting through drywall. Its never as neat.

[widgeon13]

Can't you use a router with a bit designed to just cut a line, similar to the results of a rotozip.

[75'930cab]

Yes I agree do not use a sawzall it's too brutal and will bite the lathe and pull it and make the walls crack more!
What I did was punch small holes with a hammer, one for the switch box and then couple more so I can feed the wire and ofcourse the one's for a light fixture in the ceiling. Then to fill in holes I took lathe and screwed it behind the other lathe and then filled in hole with plaster.

[75'930cab]

Here is a pic of were I placed the lathe behind the lathe to fill the hole so the plaster has something to bite on to.

[elwood-914]

I would sacrifice a couple of hole saws, they'd be your best bet. Done it many times.
Forget trying to fish down the walls for switches, get remotes for the fans. Easiest way to go I believe. $30 at Lowes or Home Depot.

[vash]

i agree, a sawzall is NOT the right tool. i watched a rotozip blade turn red hot. it went bye-bye right before my eyes.

i hate the stuff. it must have been a living hell to install. someday, one room at a time, i am getting rid of the stuff.

[Nostril Cheese]

Hole saw or drywall saw.

sawzall will rip it apart

[BlueSideUp]

Yeah the oh sh*% moment is going to be much worse with the sawzall.

[notfarnow]

OK, so now I'm curious. Is a rotozip any good going through wood? What if you hit a nail?

[trekkor]

They make a really cool hole saw with a larger clear plastic cover.

You let the hole saw pilot bit make contact with the work and then push the spring-loaded cover make contact with the cieling/wall surface.

Because it is clear plastic you can see what you are doing while all the dust and debris is contained. Pretty cool...

with the sawzall, use the plaster blade. No big deal. Use high speed and light pressure. Don't go "agro".

"Secret Tip": tape the shop vac crevice tip to the sawzall so it draws the dust right off the blade.




KT

[david914]

Originally posted by notfarnow
OK, so now I'm curious. Is a rotozip any good going through wood? What if you hit a nail?

Yup. It'll go through just about anything with the carbide bit. I installed an exhaust fan in the upstairs bathroom today. Used the RotoZip with the carbide bit to cut the hole. Ceiling is metal lath and plaster and it cut through it quite easily. I've also used the RotoZip to cut in new outlet boxes in baseboard. Does a great job.