About to bid a job which includes installing several pairs of round speakers in a lathe & plaster, which I've never done before.

It seems like it could be a big PITA ... has anyone done in-ceiling or in-wall speakers in lathe & plaster walls, what should I be aware of? Tips/tricks appreciated!

I usally use a Rotozip. Good Luck

Cut very carefully and slowly, one bad move can cause a crack or in a worst case scenario an entire ceiling to come down. Make sure you put a clause in the contract somewhere stating the possibility of something bad happening.

done it in my own house, how old is the plaster?

the main thing you have to worry about is using any kind of cutting tool on the lathe, it will start to shake and seperate from the plaster, you could be in for a major liability issue for damage caused by your installation, I would explain in the contract what you are and are not responsible for,

for my cuts, I used a special bit for my rotozip and went very very slowly, good luck

its not the plaster or the latte's that give ou problems... its the cement and steal mesh that screws me up....

thats what i have in my house in the ceilings...ugly. jig saw with carbide bits... slow and easy... took forever

ed

You can anticipate the possiblity of the wall/ceiling being too thick (depending how thick the lathe is and how much plaster was originally applied) for the speaker bracket allowance (the baffle/flange to the inside screw down clamp thingy on the speaker).

A sawzall to cut the hole may spider or chip the surrounding hole more than the speaker will cover.

I'd go with a rotozip as well

Geez...doesn't anybody work around here? Are we all just sitting in front of the computer?

I would go for carefully chipping out a circles of plaster with a small screwdriver (right tools for the right job, I know) which will then allow your circle to fall out. Warning: lots of dust and hair (don't make 'em like they used to).

Then I stitch-drill the lathes with a sharp 3 or 4 mm drill bit very carefully, making sure not to stress the lathe hence the sharp bits. Get a pack and be prepared to use them up.

Once this is done, and it takes a while, I have found that only a little cleaning up is needed here or there around the edges for a good fit. DO NOT force anything!

If you notice any cracks in the ceiling then beware, it could all come down.

It worked for me a few times, there are LOADS of old houses around here, the last one was nearly 500 years!

Good luck!

Lath.

First, are you talking about lath and plaster? That consists of 1/4" x 1 1/2" wood laths nailed to the studs or joists with about 1/4" spacing between adjacent laths. Plaster is then smeared over this, and the plaster that oozes through the opening locks the plaster in place. I've seen steel mesh or small-holed chicken wire (about 5/8" across the hole) in different installations. And I have seen various types of wallboard referred to as lath and plaster, which they aren't. That's why I ask.

First, consider the lath. It is nailed to studs at both sides of the stud bay. You want to FIRST cut through the wall and through the lath on the side of your prospective hole that is further away from a stud. For instance, there is usually 14" between studs (if there is lath and plaster, the wood might be a real 2" thick). If you have an 8" hole laid out at the left edge of the stud bay, the right edge of the hole will be 6" from the right stud.

Cut the right side first, because it is supported by both studs, even though one is 6" away and one is 8" away. After you have done the right side, you can do the left. You want to do this because if you cut the left one first, you then have 14" of lath that is supported 6" away from where you want to cut. When you start to cut, that piece of lath will flop all over the place, often breaking the plaster where you don't want it broken.

But before doing that, I have figured out where the studs are and drawn a circle in pencil. I then go around the perimeter with a 1/2" wide wood chisel that is now hopelessly dull for anything but this, and I chip at the top layer of plaster. This provides a "break line" that encourages, but does not guarantee, that if the plaster breaks, it will break along this line. This also helps me get a feel for the plaster, as to whether it is hard as steel, has voids, has weak spots, is soft, etc; that helps me adjust the speed with which I cut. By hand.

The other guys have all the other details down. I personally don't use a rotozip because it sprays very fine dust over about a square mile, even if nicely covered.

Your title referred to supporting an in-ceiling speaker in lath and plaster, but your post did not. I would be concerned about installing in-ceilings in lath and plaster for liability reasons...unless the client signs a waiver. I would install T-bars on either side of the cut-out perpendicular to the joists and anchor the in-ceiling speakers to those (probably with longer screws than provided). You may have to charge a little more, but in the end, you won't damage the original plaster, and your customer will appreciate qualified, conscientious service.

"stitch-drill"?

Hmmm...the more I read about this, the more a PITB it's sounding like - and the comments about how easy it is to damage the rest of the ceiling (and the ceiling coming down!) ... well, I'm not really filled with confidence at this, now ;)

Another option I had considered was hanging on-wall speakers to this space ... it's in the media room where these speakers need to go - the ceiling is "steeple" shaped (ach, what's the term for that again?) and rises up (at approx 30 degrees) from the main seating area, peaks, and then back down to the wall by the display area.

The side walls are too far from the seating area to hang surrounds (room is twice as long as wide, and viewing orientation is width-wise), hence my thought to use in-ceiling speakers in the angled ceiling just above the seating area ... granted, the speaker would be facing *into* the middle of the room, but presumably an aimable tweeter could compensate for that.

What if we scrap the in-ceilings, then, and use ON-walls (bipole, not dipole) that are hanging off the ceiling ... what do folks think of that approach?

Cathedral ceiling??? Are you sure there would even be enough depth for ceiling speakers?
If you were to cut them in, here is what I do (we have a lot of old houses in Seattle), but it is not my idea of fun!
1. Get client to sign off a waiver for patch and or repair work (including re - paint).
2. After marking cut-out holes lightly with pencil...(oh, and bring a fresh eraser with you!) - tape over your markings with 2 or 3 inch wide "Blue" painters tape. Thsi will keep some of the dust down - not much, but it will also help hold any loose pieces in place when cutting.
3. First, "score" your circle marking, using a Roto-Zip with the hardest bit (carbide), they make... This will take a long, long time & be super dusty, and wear eye protection!
4. You''ll begin to see some of the lath in your circular cuts through the plaster(I hope).
5. Take a jig saw, or if you are really good with a sawzall, use a fresh (buy a bunch of em, you'll burn them up fast) fine toothed blade, and slowly cut through the plath... The plath will tend to "grab" onto the blade, and start beating against the plaster, so go slow. Sometimes I use the hacksaw blades, because like cied said, there may be chicken wire between the lath & plaster!
6. You might want to have your sawzall there, because it will be almost impossible to locate the ceiling joists with your stud finder, and you might have to notch out or hack one or two!

It is a slow, tedious job, you'll burn up roto bits, and saw blades, get totally covered in plaster dust and concrete dust, and if this is a nice finished home... you should totally tarp off that room, otherwise fine dust will be everywhere in the house.

I'd figure on it taking you up to an hour per cut out... that's how I'd estimate it, plus figure a hour or two clean up time.

If you do go this route make sure the ceiling speakers you use, have those little dog-legs that can be adjusted out a couple of inches or so... cause you are usually dealing with a lot thicker deal that 5/8 sheetrock!

Can't you put in-walls in, or surface mounts on either side of the screen, and then you could just surface mount the surround speakers? It would be a lot easier, and maybe even sound better!
Good Luck:)

There's a 2' crawlspace above the ceiling

Nice!!! 2 feet makes me kind of claustraphobic!