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Drilling concrete

Asked Dec 18, 2007, 09:14 PM — 13 Answers
I am installing a tankless water heater and need to drill a 7" round hole through an 8" concrete foundation wall. The location is remote and no pros will come out for less than $400+ so I need to do it myself. I plan to drill 15 to 20 3/8" holes with a heavy duty rotary hammer and then sledging the plug out. Anyone have other ideas that would work for me I'd love to read them. Thanks,
Bob

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KISS's Avatar
KISS Posts: 12,603, Reputation: 4378
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#2

Dec 18, 2007, 09:55 PM
Try to rent a core drill

Tools Direct

7" Bits

Diamond Core Drill Bits | Cutting Concrete | Cutting Asphalt
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ballengerb1's Avatar
ballengerb1 Posts: 25,644, Reputation: 11296
Home Repair & Remodeling Expert
  
#3

Dec 19, 2007, 12:20 PM


That's KISS but with that bore costing over $300 plus renting the rotary hammer I'll be even higher than playing a pro. I appreciate the offer but I hoping for a magic bullet that hasn't come to mind. 20 3/8" holes in a circle can work but its not going to be fun. Speedball1 suggested I cut with a circlar concrete saw making a square hole and then grouting the pipe in later, also a possibliity.
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labman's Avatar
labman Posts: 10,673, Reputation: 3050
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#4

Dec 19, 2007, 01:57 PM
This is poured concrete? For block I use a big hammer and fill back in with mortar.

Some rental yards have core drills. Just bolt the base to the wall and let her rip.
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pelle's Avatar
pelle Posts: 98, Reputation: 11
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#5

Dec 19, 2007, 02:01 PM
Bob
Recently helped install a few radon gas elimination fans .. 7" hole through the concrete slabs in basements and used your method .. Granted I only went through slab thickness 4-5" but it worked well .. Only downfall took some time to drill the holes .. But once the pipe was in and all was grouted looked good ..
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ballengerb1's Avatar
ballengerb1 Posts: 25,644, Reputation: 11296
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#6

Dec 19, 2007, 03:32 PM


Thanks Labman and Pelle. It is a full 8" poured wall so I won't have gravity on my side either. HD only rents up to a 6" core but I have now found another place that has 7" and 7.5" to rent. The rotary drill is 50 lbs so I'm thinking of hanging a sling from the joist just to carry the weight so I won't spill my beer. I have seen the coring machine that hangs from the wall, glad you mentioned that option. Just can't see paying a pro $400 for this kind of low skill grunt work. I can grunt pretty good. Thanks gentlmen.
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labman's Avatar
labman Posts: 10,673, Reputation: 3050
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#7

Dec 19, 2007, 03:56 PM
Naw, all you do is hammer drill a 3/4'' hole and and put an anchor bolt in the base of the drill. I actually have worked as a core driller.
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parttime's Avatar
parttime Posts: 1,044, Reputation: 411
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#8

Dec 19, 2007, 05:05 PM
The rotary drill is 50 lbs so I'm thinking of hanging a sling from the joist just to carry the weight so I won't spill my beer. QUOTE]



Hanging is a good idea, I would also look into someway to use a hyd. Bottle jack to do the pushing on the drill, a couple of saw horses and few boards blocked to the nearest wall should make your beer drinking easier. Lol
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labman's Avatar
labman Posts: 10,673, Reputation: 3050
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#9

Dec 19, 2007, 05:21 PM
It helps to have somebody else hold the drill while you tighten the bolt. Once bolted in place, you hold the drill feed knob in one hand and the beer in the other. Whoever held the drill may need 2 beers.
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rtw_travel's Avatar
rtw_travel Posts: 344, Reputation: 179
Full Member
  
#10

Dec 19, 2007, 05:44 PM
Don't forget dust mask and ear plugs. Cement dust is surprisingly bad for your lungs.

Too bad you couldn't get a concrete coring guy out. Sometimes it helps if you talk to the individual worker rather than the office. I had one do an 8" hole through a 18" poured retaining wall for $150 cash & a beer
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