How To Install a Toilet Closet Flange On Concrete Slab

  • 01 of 07

    Toilet Flange Installation Made Easy With Hammer Drill

    Toilet Flange Resting In Place In Sewer Pipe
    Unattached Toilet Flange Resting In Place In Sewer Pipe. Lee Wallender

    If you've removed the old toilet and discovered that the existing toilet flange will not work for your new toilet because you've got a concrete slab floor, you'll find it's not easy to remove and replace.

    That scenario describes one annoying aspect of installing toilets on concrete slabs:  the difficulty of drilling into concrete.

    Job Made Easier With a Hammer Drill

    What makes this project go smoother is a hammer drill.  Unlike conventional drills which just rotate, hammer drills...MORE both rotate and move the bit up and down, ever so slightly.  For concrete and other masonry drilling, they are about the only way to go.

    You can purchase a Makita or Ryobi hammer drill for less than $100 at one of the home improvement stores or Amazon.  As a homeowner drilling into concrete once or twice a year, this type of cheap and middling quality may be right for you.  

    If you plan to drill into masonry more often, save yourself the frustration and get a Bosch, Hilti, DeWalt, or Milwaukee hammer drill.  

    Toilet Closet Flange

    This photo shows a toilet closet flange resting in place, unattached, in the sewer pipe.  This model is called a Sioux Push Tite 4" Gasketed Toilet Closet Flange.

    Flanges are key elements at connecting toilets to sewers because this is where the wax ring goes.  Not only that, they perform the job of securing the toilet to the floor and keeping it stable.

    Continue to 2 of 7 below.
  • 02 of 07

    Cut Off Old Flange and Obstructions

    Cut Off Old Bolts and Flange
    Cut Off Old Bolts and Flange. Lee Wallender

    Likely, the old flange will be in place (hopefully, the previous owners did use a flange).  You will need to remove it and any obstructions.

    In this photo, you'll see that the previous flange was attached via bolts embedded in the concrete.  As these old bolts were not long enough for the new toilet and were rusty, it was time to cut them out.

    Use an angle grinder or metal blade-equipped multi-tool to hack off these obstructions.  A hand hacksaw will not work, as you need to place the blade at...MORE level with the floor.

    Continue to 3 of 7 below.
  • 03 of 07

    Scrape Off Old Wax Ring

    Scrape Off Old Wax Ring
    Scrape Off Old Wax Ring. Lee Wallender

    The old wax ring will be in place, too.  This is a pesky little thing, as the wax is thick, gunky, and smells like petroleum.

    This step requires patience, a putty knife, and thin latex gloves.  Methodically remove all traces of the old wax ring and deposit the bits directly in a plastic bag.

    Continue to 4 of 7 below.
  • 04 of 07

    Place T Bolts In Flange

    Place T Bolts In Flange
    Place T Bolts In Flange. Lee Wallender

    Place the T bolts upside-down in the flange so that the threaded parts are sticking up.  This step is all about placement of the flange, not about installing the toilet.  Having the bolts in place helps you better visualize how the toilet will be positioned.

    Continue to 5 of 7 below.
  • 05 of 07

    Measure To Ensure Toilet Parallel To Wall

    Measure To Ensure Toilet Parallel To Wall
    Measure To Ensure Toilet Parallel To Wall. Lee Wallender

    Press the toilet closet flange down into the sewer pipe.  Use the T-bolts as positioning points.  You will want them to be equal distances from the back wall.  This will ensure that the toilet tank will be parallel to the wall.

    You can rotate the flange in either direction until you have the preferred position.

    Even after the toilet is placed, you still have the opportunity for some minor rotation.  But it's always best to get the position as straight as possible before that point.

    Continue to 6 of 7 below.
  • 06 of 07

    Drill Holes Into Concrete

    Drill Holes Into Concrete
    Drill Holes Into Concrete. Lee Wallender

    With your hammer drill and 1/4" concrete/masonry bit, bore 4 holes equidistant around the ring directly through the holes.

    Use your hammer drill's depth gauge to reach the necessary depth.

    Be careful not to let the drill bear towards the sewer pipe.

    Continue to 7 of 7 below.
  • 07 of 07

    Screw Toilet Flange Onto Concrete

    Screw Toilet Flange Onto Concrete
    Screw Toilet Flange Onto Concrete. Lee Wallender

    Use Tapcon or similar masonry/concrete screws to fasten the closet flange to the concrete slab.

    If using a plastic flange ring like this Sioux Push Tite, be careful so that you don't crack the ring by drilling in too far.