Hire the best Concreting Expert

Concreting new drain in ensuite in concrete slab

Results 1 to 3 of 3
  1. #1
    Apprentice (new member)
    Join Date
    Apr 2017

    Default Concreting new drain in ensuite in concrete slab

    Hey guys
    Just had the plumber in to lay the drain for our new shower and need to fill the trench and then lay the concrete. Literally have no idea on the concrete process and what to use for this type of application. Any ideas and tips on what to use and how to do a good Job. I am assuming that I will need to drill in to the slab and place some reinforcing in to help the new part mesh to the old slab. Anything i should know before i dive right in


  2. #2
    Apprentice (new member)
    Join Date
    Oct 2011


    A pic might be useful? What type of concrete floor is it?
    If you're renovating, I suppose it is an older house, not a 1980's plus concrete slab?

    This is from my experience on two bathroom renos - may have done the right thing or not, but it hasn't moved after 10 years....

    Older bathrooms were a concrete floor over soil, particularly where the house is on stumps or pier foundations (wooden floor).
    I'm assuming there's a trench about 25-30cm wide that's been cut through the concrete, pipes installed and backfilled.
    Maybe fill with sand instead of bits of the old floor. Rocks pressing on the new pipes can crack it and lead to leakages later.... (not good)

    If the soil is reasonably compacted, then just pour the concrete into the trench to level with the floor. You could cut some slots into the floor and lay some rod across the trench with a some mesh or wire up and down the trench. Its easy to over-engineer it. Another option is that the edges of the trench are cut on an angle so they naturally support the new strip of concrete.

    Check that the old screed has come up. The floor may be an original concrete pour with a thinner weaker concrete screed (maybe 1-3cm thick) with the old tiles sitting on this.
    The whole screed would be replaced, so filling in the hole with concrete doesn't have to be a pretty finish. The tiler will lay the screed.

    Use a sand/metal/concrete mix to fill in the floor. (Feel free to use small bits of the old floor as aggregate (metal) in the concrete).

    Good luck

  3. #3
    Apprentice (new member)
    Join Date
    Apr 2017


    Thanks mate. Yup its a 1970's house (ill chuck some pics up soon if i can) with a 10cm pad of concrete. Fill we have is very fine and no stone in it so i was just going to back fill with what we have. Going to get builders concrete (as you said a mix of all three components) but will wait until the fill has compacted a little more, Will compact as we go but will also leave to settle as well. I like the slot idea with the reo so will go with that idea. Thanks.

Similar Threads

  1. Installing a drain in concrete slab
    By Shifter in forum Plumbing
    Replies: 4
    Last Post: 20th Jul 2016, 08:45 AM
  2. Concreting onto existing concrete base
    By CADlink in forum Concreting
    Replies: 7
    Last Post: 20th Feb 2013, 06:36 PM
  3. Extend shower drain in slab
    By konect in forum Plumbing
    Replies: 8
    Last Post: 7th Jan 2013, 07:09 PM
  4. Shower drain on slab with no penetrations
    By mccallum in forum Bathrooms
    Replies: 3
    Last Post: 21st Jul 2011, 11:19 AM
  5. Replies: 0
    Last Post: 8th May 2011, 10:55 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts