I know that it needs to be raised a little bit so that the floor can slope towards the drain. But on my floor the slant towards the drain is shallow, but the floor of the bathroom is much higher (3cm/1.2in above tiles) than compared to the hallway adjoining it. It is a concrete subfloor.

I would like to re-tile the bathroom, and I would like to lower the floor... but is there a special reason why it is how it is? Am I making a mistake changing it?

It's in an apartment - all the walls and floors are concrete. There is no wood at all anywhere.

  • Don't understand any of this sorry. Is the drain for your shower or your whole bathroom?
    – DMoore
    May 8, 2013 at 5:20
  • In my bathroom there's no "shower", I have a bathtub that just stands on the floor so there's no drain inside the floor, yet that whole floor is raised (something like an inch). I guess there's big reason behind this.
    – sharptooth
    May 8, 2013 at 10:14
  • 2
    What is "much, much higher" in inches?
    – Tester101
    May 8, 2013 at 10:54
  • Could it simply be that the bathroom is tile (concrete-mortar-tile), while the hallway is just concrete/vinyl/low pile carpet (concrete-thin cover layer)?
    – Tester101
    May 9, 2013 at 15:40
  • Is this a so-called "wet-room" where there's a shower without a separate shower-tray - the whole floor collects water towards a room drain? Aug 6, 2013 at 9:44

6 Answers 6


In some older homes built between 1900-1930's it was common to set the ceramic tile in a bed of cement. The cement was poured over the subfloor. While this was a great stable base for the tile it did raise the floor. You may also have a case where the floor was damaged and during the repair or remodel they added additional layers of plywood or tilebacker to form a base for the new tile.

  • 1
    I doubt this is what she is talking about. This is maybe an inch and most of the time less. I have two bathrooms in my house like this and there are even transitions.
    – DMoore
    Aug 6, 2013 at 15:29

Because a lot of times when people remodel they are lazy and just cover up what was there. There could be layers of plywood, there could be concrete (fun), roofing shingles, backer board... I have seen people mortar/concrete over tile and lay tile. Yes you can remove it all. Worst case scenario is that you have replace a rotting subfloor with plywood. Make sure that you have a little access below this room if you are going to be demoing it all - you will probably have to cut into the ceiling below for access. At least plan on it. (See why people are lazy)


To provide space and slope for drain plumbing.

  • 2
    This was my immediate thought. In some cases, a remodel was done and they found themselves forced to raise the floor to give room for the plumbing to work correctly. IF this is the case, then lowering the floor will not be an option.
    – user558
    Aug 6, 2013 at 22:03
  • +1 since I have an apparent case of that in my own place.
    – keshlam
    Jul 27, 2014 at 5:10

I have removed transitions at the doorway and looked in from the side. You can see the layers of what is there. If you see particle board in the hallway or some other material not related to the build date, there may be an additional 1/2 to 1 inch in the bathroom area that will not be visible.


Floor joists in some old houses are spaced at 24 O.C.. Tiling over a single layer of plywood/OSB underlayment over such joists is not to code any more, and it requires a second layer of plywood. Because of that some contractors used to add second layer of plywood which resulted in higher floor levels in bathrooms.


Because the bathroom tile sits on top of layers of other materials. Beneath the tile is a layer of thinset mortar, and beneath that is a concrete backer-board which is either 1/4" or 1/2" thick. All of these layers sit on top of the original subfloor, which makes the bathroom floor higher than the rest of the house, unfortunately.

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