my house has walls that are very thick and heavy. Cutting electrical outlet holes and ceiling holes is very difficult. Using a saws all with a big tooth demolition blade, I get maybe 20 inches before the blade is flat. Ceramic blades are much worse. Am I doing it. Right? I find finer tooth blades are worse.
Even carbide blades will do it, but as you say, dusty as all get out. You could do that and square the corners with the sawzall. Personally, having cut pavers with circular blades, I'd rather just buy more sawzall blades and live with that. Maybe zek should try different blades. Maybe these.
Thanks. Sounds like they are plaster walls -- a thinner layer of white finish plaster over top of a thicker layer of gray or light brown sandy/gritty "rough coat" plaster.
Under that, attached to the rough coat plaster, should be either wood laths or maybe a metal lath/mesh.
If it is wood lath underneath, the saw blades will last longer but it's a real pain using a sawzall because the wood laths vibrate back and forth and break up the plaster pretty far around the outlet hole you are trying to create. If it is wood lath, my guess is that the plaster is destroying the demo blades because they are mostly made to cut wood.
If you happen to have metal lath under the plaster, the metal will kill the sawzall blades faster.
I have found that cutting outlet holes in lath and plaster walls is a real challenge. If there is wood lath underneath, sometimes you can use the angle grinder that someone suggested, or even one of those vibrating Dremel tools, to cut just the plaster and break it out down to the wood lath. Then use a small saw (even a hand saw for cutting drywall) to carefully cut off the wood laths while holding each lath so it doesn't vibrate back and forth while you cut it.
I have cut ceiling recessed lights and an attic entrance. The round holes need a smaller blade which goes bad fast, there is no lath or metal or wood. I'll see if I have a piece to take a photo.
I have cut ceiling recessed lights and an attic entrance. The round holes need a smaller blade which goes bad fast, there is no lath or metal or wood. I'll see if I have a piece to take a photo.
Greg
I think what you have, is rock lath plaster, it's like a layer of 1/2" sheetrock with holes in it, that's plastered over. The plaster keys into the holes. It winds up about an inch thick, and is often very hard. I usually cut outlet holes in that with a hand keyhole saw. It's work, but you're getting a clean rectangle with no big chips. For the recessed lights, Lenox makes carbide hole saws that work great. The only down side is the dust. I cut a basketball in half, and drill a hole in the center of one half, slide it over the hole saw, which helps to trap the dust and plaster particles.
Looks like rock lath, but I've never seen the plaster coat that thick. It looks more like cement than plaster. OK, so you live in a bunker. If you're near tornado alley, that's a good thing. Look at the bright side, when you're done with this project, you'll have the biggest biceps in town.
I'll say one thing, makes good soundproofing!! Just a hair over 1 inch thick.
Greg
I just did a recess lighting job in a place that was an estate garage, converted into a house about 50 years ago. all the ceilings were wire lath with about 1 -1/2" thick very hard plaster. I cut 14 - 7" holes with the Lenox. It worked really well. I don't think it dulled it at all.
Wow, that's an interesting picture. I've never seen anything like that, but I also never heard of rock lath plaster before.
In the picture, is the brownish top of the picture the inside of the wall, or is it the wall surface that shows when standing in the room?
I own a property that was built in the late 1940's. It has regular drywall/sheetrock throughout but all of the sheetrock is double layered -- two layers of regular 1/2-inch sheetrock. I don't know if it is true, but someone said to me that they believe that sheetrock was a newer form of finishing walls at that time and the old-timers didn't think 1/2-inch sheetrock would be strong enough so they double-rocked everything. I guess wall finishing was going through a transition in the late 40's and early
50's. A house I grew up in was built in 1954 and it has what is normal for today -- regular 1/2-inch sheetrock walls throughout.
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