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how to cut backer board?


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  • how to cut backer board?

    I'm installing a new floor in a downstairs bathroom on the existing joists. The old floor was completely removed and will be getting 3/4 plywood and then backer board on top of that.

    Aside from cutting the backer board to fit the whole floor area (5x9) I will need to cut holes for the shower drain, toilet and sink.

    Is there a hole cut tool for cement backer? And what about cutting to size?

  • #2
    use a carbide holesaw - the price will knock yer socks off but its the best way


    • #3
      I've never tried this, but I read in a book where you can drill a series of 3/16" diameter holes around the perimeter of the hole and punch out the hole with a hammer. I imagine a masonary bit would be necessary.


      • #4
        Get yourself a masonry blade for your circular saw, that's the easiest way or you can by a backer board scoring knife for about $10 at Lowe's/Home Depot.
        If you use the masonry blade in an old circular saw, cut a series of lines in the middle of your circle from one side to the other then you can simply score the circle perimeter with a sharp (not for long) Stanley knife and bend the pieces out.
        Ideally I use a Rotozip with a masonry blade to do smaller holes.

        NOTE wear a mask if your using the saw.
        Last edited by pushkins; 04-21-2009, 06:52 PM.
        Little about a lot and a lot about a little.
        Every day is a learning day.


        • #5
          Backerboard Shear

          If you cut the backerboard with a circular saw, wear a respirator mask and use a fan to blow away the cement dust. Breathing it is easy at first. Somwhere in the middle of the night your throat will start hurting and bleeding. I use a backerboard shear, they cost about $300 and do a real clean and relatively dustless job. Home Depot and Lowes sometimes have a board called TILE BACKER board. It is gyspum based... has a rough blue colored waterproof front, can be cut with a knife just like sheetrock, however it will hold up much longer than Purple or Green Board.


          • #6
            hardie backer cutting

            any power tools will create alot of dust which nasty stuff...wear a respirator and cut it outside.

            a makita 4" grinder makes quick and dusty work of this