Clean cuts in lathe and plaster walls?
vanderpooch
| Posted in Construction Techniques on
Hi all,
I am installing a cabinet I built tomorrow in a friend’s bathroom. In order to maximize space in the very small bathroom, he wanted the cabinet recessed in the wall. So, I need to cut a clean line around the perimeter of the cabinet. Is there any way to do this in lathe and plaster? My efforts in the past have not worked out so well (jigsaw), or have been so messy as to be eliminated immediately (angle grinder with diamond wheel).
Besides a Multi-master, which I cannot afford, are there other options?
Thanks,
Kit
Technique is proof of your seriousness. – Wallace Stevens
Replies
You had to go and add that last sentence about the MM didnt you!
I've cut away the plaster with a utility knife, make sure you have plenty of blades. Once I have the plaster cut away I break it out and then using a fairly fine bladed saw, or a jig saw on slow speed I hold my hand or a board with a cushion wraped around against the part I want to save and slowly cut the lathe. By holding the plaster that you want to save you reduce the vibration to the wall that you want to keep in place.
It's no fun but go slow and dont force the cutting of the lathe cause thats where you'll get more plaster off then you wanted!
Doug
Thanks Doug. That's good advice. The last time the jigsaw just vibrated the lathe and all the plaster cracked and fell off. Maybe I'll try it with a metal blade.I knew if I didn't disclaim the MM form the beginning I'd get a lot of recommendations for it. It's on the list for sure...-KitTechnique is proof of your seriousness. - Wallace Stevens
Like dougU said, trim away the plaster first. The problem with a saber or recip saw is that they can pull the lathe towards you, dislodging more plaster than you want. If it's a smallish hole, you can try using a manual drywall jab saw, the kind that cuts on both the push and pull, but only allow it to bite into the lathe on the push stroke. You'll work up a sweat, but if you have a good sharp saw it'll chew through lathe pretty fast. It's worth the effort if you are careful.
This is going to sound ridiculous, but I've done it several times with good results.
Take all the ordinary precautions, like tape and plastic on the door, open the window, put a fan in the window (exhaust) if possible.
Take a gallon-size plastic jug, milk jugs work OK, as do laundry soap jugs. Cut the bottom out in a scoop shape, cut the neck to fit your shop-vac hose, duct tape it to the hose, install a new filter in the shop vac.
Use an angle grinder with a diamond wheel, have your helper hold the shop-vac attachment up close to the trailing edge of the cut.
If the shop vac is in good condition there is surprisingly little dust.
Second on the utility knife. It's more arm work but the dust is bigger pieces and falls on the floor. Multiple cuts is the trick. Just keep scoring it. You could use a little handsaw for the lath too.
Depends on the plaster whether a utility knife will work. Sometimes the scratch coat is concrete-hard.
If your view never changes you're following the wrong leader
I just did this! I actually posted in another thread for some advise and did some experimenting of my own.
Get a roto zip. Period.
Dry Diamond blade to get through the plaster. You get a hell of a lot of dust but if you follow with a vaccuum (shop vac) you will drasticaly cut down on dust. I also put up plastic sheeting to contain what didnt get sucked up in a small area. Also the plaster I was cutting was adjacent to our dinning room so It could have been a mess had I not taken precautions.
The plaster should just peel away with a little bit of proding. even if it adhered well to the lath, a couple of whack with a 16 oz framing hammer will get it loose and not disrupt the plaster to remain.
Once the plaster is gone, swtich out your diamond blade for a wood cutting blade and cut the lath flush.
as long as you have scored or snaped a good line, there is minimal patching required and will most likely be covered with trim anyway.
I was going to say Roto-zip too, but get the real thing and not a small hobby one like a Dremel.
I haven't done it recently so I can't be sure. But I seem to recolect scoring it repeatedly before the top coat splintered off. It's been a long time. I use the utility knives that don't have a retracting blade.
I like using hand tools when I can because of the dust. And the line doesn't have to be perfect. Almost always there is some trim that covers the cut.
Some guys like to have a lot of power tools and use them. Some guys don't feel like they've worked unless they are covered with dust.
The last GC I worked for was like that. He was nuts. Completely thowing himself at everything he did. And he expected everyone else to do the same. He wasn't happy unless he was covered with dirt and had finished in record time.
I agree with RedfordHenry --- I get best results when cutting on the push stroke to minimize pullout on the lath. But I'm sure if you experiment you'll find a technique that works well for you.
Aside from the dust problem, what's wrong with a circular saw?
A Circular is my best freind. Faster, cleaner cut line.
Dust? nothing a good vac can't grab while I'm cutting.
Try a recip saw or jig saw with metal cutting blades and the vacuum. You'll go through several blades but I get pretty smoot edges this way. Don't be tempted to go with a more aggresive tooth blade since it tends to rip, tear, & crack the plaster.
Plaster walls in a bathroom? Nothing wrong with that, but just make sure that the brown coat (base plaster) is not portland cement, and if it is then the diamond blade is your only choice. That's how they built them in a lot of homes that used plaster in the 20th century.
I would use a diamond blade regardless. Just mask the place off with plastic, seal it with duct tape, set a fan in the window, do the cut and clean up. Done. Being dirty in this line of work just comes with the territory.
IMHO, the best way to cut a nice, clean line in plaster is with an angle grinder. Baths often have metal lath and, if so, the angle grinder will do the whole job. If there is wood lath, if you want, you can use the grinder just for the plaster and use a Roto-Zip for the lath, but I usually just use the grinder. This is the fastest way to do it, but it does raise a ton of dust. If you want to control the dust, if the plaster is old and soft, you can cut a straight line around the perimeter of the cutout with a utility knife and a straightedge, and then knock out the rest of the plaster. Cut out the lath with a Roto-Zip.
The reason I do this in two steps is that the Roto-Zip bits that cut plaster well don't do very well cutting the lath, and the wood bits dull in about a second on plaster.
Mike Hennessy
Pittsburgh, PA
I've used a roto zip for this many times. just mark and score you line on the plaster. Use the plaster bit and cut out your hole just in in the plaster(set tthe roto zip blade to the proper depth) take out the plaster within your hole. take a look at the lathe and behind it. Make sure there is nothing that will interfere with what you want to do. Now swith the bit to a wood cutting bit and the proper depth and cut out the lathe to complete your hole. Using the roto sip really limits damage to surrounding lathe. Use a shop vac with hepa filter and a partner to hold it for you will greatly reduce amount of dust.
good luck
Well, to follow up...
I did the knife double score, raked out in between with a drywall saw. Smacked all the plaster off in the opening, and then cut around the edge with jigsaw hooked to vac. No cracks, super clean line, with a 3/16 margin all the way around the cabinet.
Although it was still a mess, with chunking all the plaster off (the cabinet is 24" wide by 7' tall), there was really no dust, which was my concern. I was able to do the job with the tools I had and it came out great.
What I didn't think about was pulling the studs, which are of course nailed to the lathe on the other side.... That one took a while, but with two little prybars and some patience (not my strong point) I was able to remove two studs without cracking any of the plaster. I'll post a pic after I install it tomorrow.
Thanks for all the input, couldn't have done it without you!
- Kit
Did you put in any kind of header? Is this a bearing wall?
It is not a bearing wall, but I did head it out, as well as placing studs at the edges of the opening.Technique is proof of your seriousness. - Wallace Stevens
--"What I didn't think about was pulling the studs, which are of course nailed to the lathe on the other side...."Don't feel bad, I was once removing old kitchen cabinets and the lathe on the other side of the wall was nailed to the back of the cabinets...no studs in the wall, and it was a load bearing wall--uh, erh--load bearing cabinet I was removing. Something I had never seen before and have not seen since.
The studs were also run flat to the length of the wall, something I haven't seen before. These are full dimension 2x4's. The house was built in the teens or twenties.-KitTechnique is proof of your seriousness. - Wallace Stevens
I expected to find the wall studded on the flat when I was removing that cabinet...but then to find no studs...boy did I have a dumb look on my face.That floor to ceiling, wall to wall, built-in cabinet had vertical double lathe nailed to the back of the cabinet on 16" centers to give the plaster a place to key in and then horizontal lathe nailed to the vert. lathe.
Edited 9/26/2007 9:06 pm ET by basswood