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Thread: How to drill 2.25" hole in cinder block wall?

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  1. #1

    Default How to drill 2.25" hole in cinder block wall?

    I'm installing a 5-zone drip irrigation system. I'm locating the control valves in my garage, whose walls are concree block with brick veneer on outside.

    The poly pipe is 0.700" OD.

    Rather than drilling five separate holes through the wall, I want to drill a single hole through the concrete block and veneer. The size of the hole needs to be large enough to accept a sleeve of 2" PVC (to protect the poly pipe and to allow for winterization).

    I have a complete set of bi-metal hole saws, but none for cuttng through the concrete block.

    Any recommendations?
    Thanks,
    Joe in Virginia

  2. #2
    Master Plumber nhmaster's Avatar
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    Home Depot rents a hammer drill and core drills that will buzz though in no time and leave a nice clean hole.

  3. #3

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    Quote Originally Posted by nhmaster View Post
    Home Depot rents a hammer drill and core drills that will buzz though in no time and leave a nice clean hole.
    The nearest Home Depot rental store is about 150 mi. away. I already own a hammer drill and an arbor that holds a 2-1/2" bi-metal hole saw. I was hoping to purchase just a single saw to fit my existing arbor.
    Thanks,
    Joe in Virginia

  4. #4
    Master Plumber nhmaster's Avatar
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    I doubt the bi-metal will hold up long. You need a diamond core bit.

  5. #5
    DIY Member msgale's Avatar
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    i dont think youcan drillthru, although perhaps a diamond bit might work,i don't know anything about them.
    But your hammer drill probably will drillthru, with a regular masonry bit,a series of small holes,then punch out the middle, Not too neat, you will have to patch around your larger pipe to fill the irregualrities.
    or you can buy a cheap harbor freight demolition hammer, for less money than 300 miles of gas, or almost less, and punch ah big hole. Easier than a hammer drill,but still not neat round cuts.

  6. #6
    In the Trades Master Plumber 101's Avatar
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    If you can't get a dry core bit you will have to do as you stated drill multiple holes and try to keep it as clean as possible.

  7. #7

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    Quote Originally Posted by nhmaster View Post
    I doubt the bi-metal will hold up long. You need a diamond core bit.

    Would a carbide-tipped bit stand up? Keep in mind that the voids in the cinder blocks are not filled with concrete, so I only need to to drill through one inner and one outer wall--about two inches in all.
    Thanks,
    Joe in Virginia

  8. #8
    Master Plumber nhmaster's Avatar
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    Yes, carbide will work. Not as clean a hole but that's how we did it in the old days.

  9. #9
    Sprinkler Guy Wet_Boots's Avatar
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    Quote Originally Posted by TigerDriver View Post
    I'm installing a 5-zone drip irrigation system. I'm locating the control valves in my garage, whose walls are concree block with brick veneer on outside.

    The poly pipe is 0.700" OD.

    Rather than drilling five separate holes through the wall, I want to drill a single hole through the concrete block and veneer. The size of the hole needs to be large enough to accept a sleeve of 2" PVC (to protect the poly pipe and to allow for winterization).

    I have a complete set of bi-metal hole saws, but none for cuttng through the concrete block.

    Any recommendations?
    Yet another reason why only the DIY crowd ever installs lawn sprinkler zone valves anywhere but outside.

  10. #10
    DIY Senior Member Phil H2's Avatar
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    Tiger Diver,
    Just a heads up. If you plan on using 2" PVC pipe for a sleeve, it won't fit through a 2-1/4" hole. The outside diameter is 2-3/8"

  11. #11
    In the Trades maintenanceguy's Avatar
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    If it's just one hole and you're careful to hit a void in the block and not hit one of the webs, you can do this with a hammer and chisel in under 5 minutes. Concrete block is very easy to break with a hammer.

    Punch (or drill) a small hole to get you started and work around the edge of that hole until it's as big as you want.

    I've opened 3'x3' access holes in block with a hammer and chisel lots of times and it takes me longer to haul the broken pieces out to the trash than it does to make a nice square opening.

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