boring hole in foundation?

I'm interested in boring a 2.5" round hole in the foundation of my house. I've got a sump pit that I wish to upgrade to a sewage pump and 2" abs hard pipe (which is just less than 2.5" around by my measure). any DIY ideas on how to attain this? I've seen the roto-hammer and coring bit for rent at the home depot, but am afraid I've never even witnessed its use, let alone done it! do I attack the wall with the SDS Rotohammer and coring bit the same as I might a regular drill and holesaw to wood?
I'm very mechanically inclined, so I'm not at a lack of skill...its the experience. any thoughts on this? It had been suggested to do it the hard way...with a hammer drill and long masonry bit, drill successive small holes around the perimeter of the large one, and knock/chisel it out. That not only sounds very time consuming and labourous, but imprecise.
any advice would be appreciated.
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hard
on
hard
holes
The roto-hammers and coring bits rented from HD are the best thing since sliced bread. I drilled a 4" hole in cinder block foundation in about 5 min without effort. The thing even had a clutch that disengaged the bit if I locked it up. In solid concrete you would need to chisel out the core, but that should be easy.
EJ
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Forget makeing or corimg a Nice hole , use a power jack demolition hammer, make hole larger and fill it in with concrete, Bust through quick;........
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<< do I attack the wall with the SDS Rotohammer and coring bit the same as I might a regular drill and holesaw to wood? >>
Just use the coring bit in the closest size the rental place has. Use a spritz bottle with water to keep down the dust and wear your safety glasses and dust mask. Some hammer and cold chisel work will knock the core out enough to let you bore clean through. You will probably need up to an hour to go through a good solid 8" concrete wall. Good luck.
Joe
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Hamilton Audio wrote:

??? Why?
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
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haha...wondered when that question was gonna come up. the house is a montreal-style bilevel, with the garage in the basement parallel to my rec room (they are of equal size). thus, the driveway has a notable slope towards the house and down. the top of my garage door (7.5' tall) is just slightly higher than the bottom of my front door at grade, if that draws the picture for you.
in front of said garage door is a nicely formed concrete channel that captures all water coming down the driveway. it collects it, and when sufficiently full starts spilling into a downspout into the weeping tile system of the house, and then into the sump pit. no other possible means in this situation to meet code :(
hence, in large rainstorms and such, the flow into the sump pit is substantially larger than you would ever dream of! like a freakin fire-hose pouring in there, and the 1/2 horse Star sump pump I bought kept up, but just barely. then there is the issue of debris. the driveway will filter in small sticks, leaves, blades of grass and other small junk into the channel and eventually into the pit. this is obviously NOT good for a normal sump pump to be pushing.
so, this is an attempt to rectify 2 issues. 1. capacity - a 1/2 horse contractor grade sewage pump has more than double the GPM flow rating of a comparable 1/2 horse standard sump pump. couple this with a substantially larger pipe (1.25" corrugated to full 2" abs) and my capacity is MUCH better. a civil engineer I work with helped me work it out on paper. I'm gaining roughly 66% flow capacity over the existing system by gaining on the pump and the pipe. 2. debris - the sewage pump I've purchased will happily pass grass and leaves all day long with no threat of clogging or damage. NO MAINTENANCE!!!
hence, the 1" abs pipe that currently passes through my foundation is substantially not large enough, and i figured if I was gonna go big, I might as well go all the way!!

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Good points.
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
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The hole you're drilling isn't the centerpiece of the house, so, "precision" isn't really that necessary.
I wouldn't go for a tight fit with a drill. Make sure it's reasonably generous (ie: go up a size if it's a snug fit). You're going to be packing the hole with foam and/or caulk anyway, so imperfections are irrelevant.
If it's cinderblock, many pros don't bother with a drill. I've watched electricians "drill" holes for 2" service entrance conduit thru cinderblock with an ordinary claw hammer and only occasionally a cold chisel.
The results were surprisingly neat and fast.
I've tried it myself and did fine.
For poured concrete, I'd probably go with renting the "proper" drill. They're really not that much different then ordinary drills, just a lot heavier. Right way to go if you'd have to rent a suitably beefy hammer drill in any event.
Once you're setup and braced properly, they're easy to use.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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