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Thread: Drilling through split-face concrete block

  1. #1
    Join Date
    Apr 2007
    Location
    New Jersey
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    13,721

    Drilling through split-face concrete block

    I am looking to vent my dust collector to the outside of my workshop. However, the exterior wall is split-face concrete block. I'm looking for suggestions about how best to cut a 6" hole through the block, or advice to hire a contractor, or advice that I shouldn't try to do this in concrete block...
    Thanks in advance.

  2. #2
    Join Date
    Jan 2004
    Location
    Lewiston, Idaho
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    28,504
    A contractor might have a special diamond toothed drill bit to do it.

    I would rent a hammer-drill and drill a series of holes in a circular pattern and then hammer the resultant disk out.

    To reposition a drain for a larger shower, that is how I did it in my basement floor. How thick is the wall?
    Ken

    So much to learn, so little time.....

  3. #3
    Join Date
    Jan 2010
    Location
    Montgomery, Texas
    Posts
    287
    Do you know if the cells are fully grouted or if it's reinforced with rebar (vertically)? As I recall, your shop is located in your industrial facility so the application potentially won't be as simple as coring through a block wall in a residential building. Find a a core drill rig and the corresponding core bit to rent from a construction equipment rental outfit. More than likely, the rental cost of the core bit will be as much as or more than the core drill rig.

    Otherwise, try to find a core drilling company that specializes in concrete sawing and drilling. With the expense of the rental costs, you might find that contracting someone may not be much more expensive and they'll likely scan the wall to confirm no conflicts in the core location. The majority of their time spent (and associated cost) will be in the setup and breakdown of the equipment, not in the amount of time to drill the core. Also, if you have some flexibility with schedule, ask if there's any difference in price if they work you in on a day where they don't have a full schedule. Otherwise, the price of the job could be based solely on having the crew billable for say a half day's worth of work.

  4. #4
    Join Date
    Nov 2003
    Location
    Central North Carolina
    Posts
    1,830
    What Ken said.
    Plus, start from the side that you least care about when you start hammering out the center. It is likely to break away an area that is larger than the hole that you want on the back side and a patch won't show as much on the smooth interior side of the block. Take your time and don't try to knock it out in one piece. Chip away at it slowly with a moderate size hammer and it will likely turn out more successful with very little to patch. The web across the center or either end of the block will need to be broken out very carefully.

    Charley

  5. #5
    Join Date
    Feb 2010
    Location
    Middle Earth MD
    Posts
    682
    Additionally, you can start with a small center hole bored all the way through the wall to locate and mark where the hole is on both sides of the wall then work your way through by drilling/chipping from both faces to get the hole to it's final size.

  6. #6
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    Like Brett says.

    Get it core drilled. I happened to see an ad for a local guy last nite on CL. His minimum was $100.

    Rick Potter

  7. #7
    Join Date
    Nov 2011
    Location
    Pueblo, CO
    Posts
    28
    I have spent most of my working life in the masonry business and I recommend you get it core drilled. I have seen many people attempt to do it with a hammer drill and end up breaking the block and then having to have a mason remove the block and install a new one. If it is a reinforced cell (grouted and rebar) you are in for a pretty good expense. You also want something that can get a tight seal around the hole so you do not get water intrusion into the building. It is not much of an issue in a very dry climate but up in your part of the country it can lead to some serious problems. The core can be expensive but in the long run provides a better seal, a cleaner hole, and if you ever need to sell the building an easier hole to plug.

    Mark

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