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tomary

can you convert a center drain to a trench drain?

tomary
January 29, 2013
Doing a shower remodel. Converting shower into a curbless one and would like to get rid of the center drain. The shower is on a concrete slab.
Can the center drain be converted to a trench drain?

Comments (8)

  • PRO
    Norm Walters Construction Inc.
    Yes it can. you would have to chip the concrete to the new location of the center of the trench drain, and also chip the concrete for depth of the trench drain. Make the slot in the slab for the drain wider than the drain so that the drain can be concreted in. Most trench drains attach to PVC or ABS with a Fernco fitting, (basically a rubber boot with clamps).
  • PRO
    Ironwood Builders
    Norm, how would you handle the slope from the existing curbed shower to the curbless with a back center drain? We've done some curbless showers but always in wood framing. The last whole house poured slab we did, the showers were cast into the slab, curb and all with a 12X12 hole for the pan drain. I know you are out in Florida, lots more slab on grade out there.
  • PRO
    Norm Walters Construction Inc.
    David, the shower shown in the picture was originally a tub next to a recessed shower. For the recessed area I had to get creative. We ran the two inch line and trap to the new location and I used about a foot of the cardboard tubes used for pouring columns, cut a notch in the tube and put a two by four the length of the drain in the notch. The recess shower was then poured, when still green I pulled the tube and the board. Using the column tube we were able to connect the Fernco fitting and install the drain, then fill the void left by the tube with concrete.
  • PRO
    Ironwood Builders
    OK! New shower floor! Not an option on our structural slabs, or not without an engineer!
  • tomary
    Thanks for the info. With the currnent center drain located in the middle of the shower-is it possible to locate a trench drain against the back wall? Planning on lowering slab 2 inches to have curbless shower but cannot find any info on how to connect current drain with trench. Trench would be about. 18" from drain pipe.
  • PRO
    Norm Walters Construction Inc.
    How are you lowering the slab?
  • tomary
    I would think that the area of the shower which is 5ftx5ft would be broken up and "chiseled" out to lower the slab by 2"; enough so that it would start flush with the bathroom floor and slope to the back wall toward the drain.
  • PRO
    Norm Walters Construction Inc.
    Your slab is most likely 4" thick, you would have to chisel out the whole area as I don't see how you could only remove 2 ". You would then need to remove soil so that 4" of new concrete could be poured, lower. If your shower is 5' wide you would need 1-1/4 inches of slope overall, (1/4" inche per foot) this is not done with the concrete. The concrete would be poured level to a point 1-1/2" below the existing slab that it joins. You would then make your slope with dry pack mud. Over this I would put either Shluter membrane, or Noble Seal TS membrane, this method will keep you from having to do a pvc liner and then a mortar bed, causing you to go even lower in the ground.

    Here are two problems that may occur with this whole process, your drain may not be able to be lowered depending on how low the pipes are going to the drain now, plus you are adding piping to get the trench drain and all of that pipe needs to be pitched. The other problem is that if your house is block with a monolithic slab, there is a one foot wide concrete foundation pour in conjuction with the slab. Concrete block is 8" wide, the foundation is 12", that leaves 4" of concrete that you can't chip because you can't disturb the foundation. Two ways to get around that problem, one, frame a wall to the existing wall, or two, put a bench in the shower the whole length such as the one in my photo above.

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