Putting a hole in a concrete slab

[Jack]

I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

[3D Peruna]

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

How big of a hole? I'd rent a core driller. It's a little messy, but less
dust, if you put up some plastic to control the splashing. Less work, I
suspect, too.

[Bob Morrison]

In a previous post Jack wrote...

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

It might be easier to build a temporary wall covered with plastic around
where you want to work, then rent a saw (or hire someone)and cut the hole.
You will have less chance of cracking the slab and the hole will have a
nice neat edge. The dust can be vacuumed up before you take down the
temporary wall.

[M&S]

Post by Bob Morrison
In a previous post Jack wrote...

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

It might be easier to build a temporary wall covered with plastic around
where you want to work, then rent a saw (or hire someone)and cut the hole.
You will have less chance of cracking the slab and the hole will have a
nice neat edge. The dust can be vacuumed up before you take down the
temporary wall.

Better yet, call a local stone mason and see if they will come over with
a gas or electric saw and cut it for you. You can run a garden hose to
the location, they hook to thier saw and VERY little water will
elliminate 99 percent of the dust.

You could easily caulk down a curb of 2x4s around the hole to keep the
water in the area. As soon as the first cut makes it through the slab
the water will all drain into the hole. Simply pop the 2x curb up and
you are done. Clean hole, no cracks, less than an hours work.

Cutting a 30" square hole in a slab by drilling small 1/2 holes is a lot
of work. If you insist on going that route I would use a 1/2" or smaller
bit. 3/8" would be even better. To get the slug out easily you would
want to drill the holes very close together 3" or so. It will take a lot
of sledge hammer work to get it started but once you get a bit of it out
you can excavate a little material out from under the remainder and it
will break out easier.

Make a few calls, you could perhaps get someone to come out and cut if
for a reasonalbe price. Or rent an electric masonry saw for 100.00 a day
and cut it yourself.

Mark

[Dan Deckert]

Assumming you use the rotohammer, drill the perimeter as reasonably close as
you can get the holes together. Then cross drill the center of the square to
get it smaller for removal. AND drill completely thru the slab/ every hole.
Just pray there's no buried power/water/sewer/etc. below the slab. AND ya
better hope there's no rebar in the slab, else...........SAW Time. Hole size
can be anything you want, the smaller & closer the holes, the neater the
edges, "assumming you drill in a straight line". Maybe use a 2x4 for
aligning?

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Although the above method is 'plenty dusty' if done dry! Use a squirt bottle
with water to keep the dust down. BTW, a vacum will suck up a lot of dust
while drilling, BUT it'll blow it back out unless it's a HEPA vac. Frankly,
I'd go rent a Chop Saw with a diamond blade or else call a Concrete Cutting
outfit and saw the hole out. 15 minutes to cut the hole, 15 for clean up,
noisy as hell though.......plus the exhaust. Have fun.......

Dan

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

[butch burton]

Rent a gas powered saw - wear ear and eye protection.

[fulrok]

I'd just rent a 60 lb. electric jack hammer and forget about sawcutting.
Use a 1" chisel bit to get started and once punching through, switch to a
4" bit. Just rought cut it .

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.

[gary]

I put a sump pit in my basement 2 years ago. I rented a jackhammer and had
the proper sized hole in there in about 15 minutes (including pulling out
the concreter chunks). I went so fast that I decided to chip out and
replace the old cast iron plumbing under the concrete while I was at it and
set up for a toilet and tub in a new (to be) bathroom. Its a good thing
that I decided to do that at the old sewer line had holes in it an part of
it was like tinfoil. I replace it to under the footing as far as I could
dig. I suppose it will have to be replaced on the outside of the house one
day soon too. *sigh*

Post by fulrok
I'd just rent a 60 lb. electric jack hammer and forget about sawcutting.
Use a 1" chisel bit to get started and once punching through, switch to a
4" bit. Just rought cut it .

Post by Jack
I need to put a hole in a basement floor. To save my wife from all the
dust, I am going to drill holes with a hammer drill, then break out the
concrete.(instead of sawing it) The hole will be about 30 inches square.
Question: How many holes would you drill around the perimeter? Size of
drilled hole? I have a 3/4 in hammer drill.. How deep do I need to drill
the holes. I was thinking of going right through the slab.
Thank you for your time.