Anybody ever cut through a concrete block (cinderblock) wall?

flot

Diamond Member
Feb 24, 2000
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So I want to open up a couple 6' wide holes in a couple of walls. One wall currently has a window in it - basically I just need to cut straight down to make a door-sized opening. The other wall, well, same thing - just without the pre-existing hole.

But... the question is - what's the best tool for the job? Or do I even have options? The only thing that comes to mind is a big gas powered circular saw like you'd use to cut a sidewalk... ?
 

funboy6942

Lifer
Nov 13, 2001
15,295
391
126
If you use a saw or anything that going to kick up dust make sure to use a respirator. Concrete is silica which in dust form is a cancer causing material. Would go fo rthe full face mask and cans, not the paper crap it wont do a thing for you.

So you dont think Im talking out my ass.
It kills me to watch these guys with the big saws stand behind them in a cloud of dust with nothing on. No job is worth killing yourself over even if you look like a pussy. It can really mess your sh!t up.

More info. Feel free to google cance and concrete if you want to read even more on it.
 

lokiju

Lifer
May 29, 2003
18,536
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I can't think of anything else other than a gas saw that will cut through it cleanly.
 

Bateluer

Lifer
Jun 23, 2001
27,730
8
0
I've used a large sledge hammer to smash through some cinder block walls before. Sounds like you're going to need something smoother though. :p
 

Atheus

Diamond Member
Jun 7, 2005
7,313
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You want a big electric saw with a concrete cutting blade. They're not really blades, more grinding wheels, often diamond tipped.
 

bctbct

Diamond Member
Dec 22, 2005
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Typically you would use a quicky saw with a diamond blade. Use a hudson sprayer with water aimed at the blade and you will reduce the dust to nil. If it is a 7 5/8" wall you will have to cut both sides though using a 14" blade.

Really though if you have a few extra funds I would call a concrete cutting company. Have the holes laid out and ready to go. They will come and probably use a ring saw which with cut the corners tight (since blade is round without overcutting hole, the corner will have about 6 inches uncut). Also they will use a saw that will cut all the way through from one side

Probably wont cost much more than renting the right equipment. Concrete cutting company usually will not touch the debris so clean-up is left for you.

Also if you are cutting a new hole it will most likely have to have a lentil installed if there is remaining block above the opening. If you look at the window hole it should have a solid 1 piece block all the way across the window head.
 

dartworth

Lifer
Jul 29, 2001
15,195
1
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Originally posted by: bctbct
Typically you would use a quicky saw with a diamond blade. Use a hudson sprayer with water aimed at the blade and you will reduce the dust to nil. If it is a 7 5/8" wall you will have to cut both sides though using a 14" blade.

Really though if you have a few extra funds I would call a concrete cutting company. Have the holes laid out and ready to go. They will come and probably use a ring saw which with cut the corners tight (since blade is round without overcutting hole, the corner will have about 6 inches uncut). Also they will use a saw that will cut all the way through from one side

Probably wont cost much more than renting the right equipment. Concrete cutting company usually will not touch the debris so clean-up is left for you.

Also if you are cutting a new hole it will most likely have to have a lentil installed if there is remaining block above the opening. If you look at the window hole it should have a solid 1 piece block all the way across the window head.

:thumbsup:

great advice...
 

arrfep

Platinum Member
Sep 7, 2006
2,318
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Also if you are cutting a new hole it will most likely have to have a lentil installed if there is remaining block above the opening. If you look at the window hole it should have a solid 1 piece block all the way across the window head.

Good call. Don't want that wall to come crumbling down. I believe I've also seen low-profile steel pieces you can use for a retrofit
 

marvdmartian

Diamond Member
Apr 12, 2002
5,549
19
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Go find a computer case modder, and ask to borrow his dremel, and some cutting disks! ;)

Honestly, while an electric circular saw with a masonry blade would work, a 12" or 14" gas powered chop saw would work so much better. The only real advantage the smaller saw has is it's lighter weight, though you're prolly going to take longer to make your cuts, and I'd recommend resting your saw every so often, to let the motor cool off. The chop saw will likely put out a LOT more dust, but will make smooth, straight cuts without having to struggle to get it through the block. If you're going to use the bigger saw, I might advise practising once or twice, in the middle of the area you're going to remove, to make sure you can control it okay! ;)
 

bctbct

Diamond Member
Dec 22, 2005
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Originally posted by: arrfep
Also if you are cutting a new hole it will most likely have to have a lentil installed if there is remaining block above the opening. If you look at the window hole it should have a solid 1 piece block all the way across the window head.

Good call. Don't want that wall to come crumbling down. I believe I've also seen low-profile steel pieces you can use for a retrofit


Yes you can use a steel T lentil which is two pieces of angle iron welded back to back.
 

wedi42

Platinum Member
Jun 9, 2001
2,843
0
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you can rent the saw you need, get an electric one.
like this
measure carefully inside and out, you'll have to cut from both sides.
find your local rental store here
should cost you $100-150 depending on how much blade you use up.
 

flot

Diamond Member
Feb 24, 2000
3,197
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Thanks guys. I could have rented a big gas circular concrete cutting saw from home depot + a diamond blade for $100.

But I added up everything I wanted to do, which was basically 2 new large doorways and expanding 1 smaller one and it came out to about 40 linear feet of concrete cutting. I would have to do the same cut from each side so call it 80 feet. That's a lot of cutting.

I found a local concrete cutting contractor (which amazed me) that was very professional and they're going to charge me about $400 to do the job, plus they can do it all from the outside which is a huge plus as it means my kitchen won't get destroyed in the process.

Specialized contractors FTW.