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Thread: Removing cement board from wood floor. Demolition hammer?

  1. #1
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    Removing cement board from wood floor. Demolition hammer?

    Heaven help me. This hot mess started because my wife wanted to paint this guest bathroom walls grey. One thing leads to another and I'm mightily frustrated trying to get this cement board up. Evidently drywall screwed randomly every few inches you can't access the screws because they are hidden by the layer of mastic that adhered the tile. Trying to drive my pry bar under it just causes it to crumble into pieces and takes forever. I've never used a demolition hammer. Will something small with a wide chisel break or cut through the drywall screws? I don't want to rent or buy if the screws are just going to ruin the chisels edge in short order. Open to other ideas to end this nightmare. IMG_5524.jpg I'm at a point I'm considering trying to remove the sub floor boards with the cement boards attached but don't want to open another unknown can of worms.
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  3. #3
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    I hate using drywall screws for anything but drywall, but in this case, they may be a good thing. They're much more brittle than wood screws & I think the wide chisel in an electric hammer might just do the trick. I feel for you, having had to pull up glued-on underlayment in 2 of my kids' kitchens to do new flooring. It's almost the worst home reno job there is.

  4. #4
    I'd try an air chisel before anything bigger. You may be able to get a wide blade (like Lowell linked to) between the layers and just buzz through the screws.
    https://www.harborfreight.com/air-to...kit-92037.html

  5. #5
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    They may be actual cement board screws...which will not break easily...and from above, they may look like drywall screws. You may need to break that cement board apart into tiny pieces to remove it. That's what I had to do with it for the section I had to remove when I renovated my older daughter's bathroom a few years ago here. Same screw pattern...lots of them. Tedious and messy work.
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  6. #6
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    Break the cement board using a prybar to lift and then slice cut the screws using a multi tool with metal cutting blade.

  7. #7
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    Thanks for the advice. Just got back from HF. They close at 8:00PM. Kind of strange. Anyway after beating on this again this afternoon I decided I'm too old to take the necessary time. Tomorrow morning I'll go to HF again and get a small, but not their smallest, combo hammer/drill with a coupon. If it turns out the screws are tougher that drywall screws and it won't break them at least hopefully it will speed up the process of breaking up the cement board. This was a 70's remodel and from the general overall quality of finishes and materials otherwise I'm hoping they didn't spend extra for special screws. We shall see.
    Never run with bagpipes. You might put your aye out. Or worse, get kilt.

    The problem with humanity is: we have paleolithic emotions; medieval institutions; and God-like technology.

    I miss DOS when you knew what was on your computer, how it got there and what it did

  8. #8
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    Quote Originally Posted by Michael Weber View Post
    One thing leads to another and I'm mightily frustrated trying to get this cement board up.
    What will the new floor be? How clean must you get the underlayment before installing a new floor?

    If you have to remove the screws one-by-one, I suggest unscrewing those whose heads happen to be clean with an impact driver and cutting the rest off with a grinder.

    Maybe there is a tool that grabs screws on the sides of the head and unscrews them - something better than unscrewing them with pliers.

  9. #9
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    This is what I used in a small bathroom to pull up the tile. The shank has bend so it can float above the subfloor. I suppose they come wider? I really had to lean into it to get the hammer effect going.
    Bil lD.
    https://www.homedepot.com/p/Bosch-2-...1915/202242696

  10. #10
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    Quote Originally Posted by Stephen Tashiro View Post
    What will the new floor be? How clean must you get the underlayment before installing a new floor?

    If you have to remove the screws one-by-one, I suggest unscrewing those whose heads happen to be clean with an impact driver and cutting the rest off with a grinder.

    Maybe there is a tool that grabs screws on the sides of the head and unscrews them - something better than unscrewing them with pliers.
    Going to be tile again. I admit there was a better way to do this and I've made a lot of unnecessary work. Too late to go back now.
    Never run with bagpipes. You might put your aye out. Or worse, get kilt.

    The problem with humanity is: we have paleolithic emotions; medieval institutions; and God-like technology.

    I miss DOS when you knew what was on your computer, how it got there and what it did

  11. #11
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    Quote Originally Posted by Bill Dufour View Post
    This is what I used in a small bathroom to pull up the tile. The shank has bend so it can float above the subfloor. I suppose they come wider? I really had to lean into it to get the hammer effect going.
    Bil lD.
    https://www.homedepot.com/p/Bosch-2-...1915/202242696
    Thanks, I like that bend.
    Never run with bagpipes. You might put your aye out. Or worse, get kilt.

    The problem with humanity is: we have paleolithic emotions; medieval institutions; and God-like technology.

    I miss DOS when you knew what was on your computer, how it got there and what it did

  12. #12
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    I some times use a drill that I tighten the chuck on the head of the screw and back it out.

  13. #13
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    Quote Originally Posted by Jerome Stanek View Post
    I some times use a drill that I tighten the chuck on the head of the screw and back it out.
    I think the issue is that the OP can't really get to the screw heads because of the mastic that's on top of the cement board. I had the same issue when I did the work I mentioned in my previous comment.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
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    That is my least favorite job in a remodel. No matter the direction you choose, it will require violence. Get something like a Bosch Bulldog SDS with a flat chisel, a sawzall and a grinder.

    Normally though the tile is coming out for more tile, so there is a different approach that usually works better. Check your flooring heights and you will probably find that you actually don't want the new tile as high, so you are looking at taking off layers. Also, tiling over diagonal solid wood subfloor is a no-no, so that has to be at least sheeted with something else then a decoupling membrane, then tile. What I mean is, usually the subfloor needs to come out so just sawzall the works out in chunks and resheet the floor with modern materials. It'll save you time and effort, and give you a better end product.

  15. #15
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    Yea, my whole kitchen floor was like that, and over 1/4" luan. Ended up using a couple of wrecking bars under the luan to pry up the whole mess after cutting it into 2 foot squares down the grout lines with an abrasive blade in my skill saw. Worst part? I was the one that put down the cement board over thinset with plenty of screws then tiled on top. Look at the HF drill/demo hammer at under $100.

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    Last edited by Ole Anderson; 10-22-2019 at 10:46 AM.
    NOW you tell me...

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