(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 10 of 10

Thread: Cast concrete soaking tub

  1. #1

    Default Cast concrete soaking tub

    Hi
    I'm planning on forming and casting a Japanese soaking tub (Ofuro) from concrete. The tub will sit on a sturdily reinforced slab on grade concrete floor. Dimensions will be 42x42 by ~36" high and the walls will be ~4" thick. (The slab has insulation, PEX for radiant heat and vapor barrier under it in case that matters).

    When my plumbers did the under slab rough-in, they boxed out an area under where the tub will eventually sit, leaving what amounts to a hole in the slab where the trap and drain will presumably be brought up.

    Questions:
    #1. Can I have the plumber install the trap and drain at the appropriate location/height and then pour around them, filling the hole and forming the floor of my tub, or is there a reason these can't be embedded in concrete?

    #2. I assume a regular tub drain and stopper mechanism won't work in this situation. A floor drain and flat rubber stopper are fine as far as I'm concerned, but will this meet code? Is there a better solution?

    #3. What about the overflow? Do I have to have one? If so, how to do in concrete?

    #4. I was told that it's a bad idea to put valves and fixtures directly in concrete because it makes repair or replacement difficult to impossible, so I've planned to locate the fixture in a framed wall that backs up to one of the tub walls. Is there any better way?

    Thanks in advance for any advice!

    http://www.woodentubs.com/tubs_ofuro.html
    Last edited by Terry; 05-30-2012 at 11:04 PM.

  2. #2
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,201
    Blog Entries
    1

    Default

    The worst problem with a concrete tub, is heating it. If it were a hot tub, it would be constantly heated and ready to use.

    Since this is a tub, you will have a hard time overcoming the solid mass of concrete that will be needed to be brought up to temperature.


    http://www.arpbathtubs.com/
    This is what I used when I wanted a tub like that.
    They make cable waste and overflows that may reach high enough.
    or in my case, I bent some some copper rod and extend a PP W&O.
    You could also use standard glue type W&O fittings.
    Last edited by Terry; 05-30-2012 at 11:04 PM.

  3. #3

    Default

    The house is heated with hydronic radiant. Since I installed the PEX myself, I was able to place extra loops under the tub location to keep things warmer in that area. Since the tub will be continuous with the floor, I anticipate the temperature of the concrete structure will remain at or near that of the underlying slab (~80-85 degrees)...one of the many comfortable benefits of the heat-transfer effect of radiant. Hopefully this will offset the heat loss from the water enough to avoid the need for a separate heater.
    Were it not for using radiant, I wouldn't have considered a concrete tub for exactly the reason you mentioned. If it ends up that I still lose all the water heat to the concrete, I'll look into one of those ofuro heaters.

    I have looked at the tub pictured previously and would consider it as a last resort. Honestly, I think it's ugly and not in keeping with the look of rest of the room/house.

    Thanks for the tips on the overflow.
    Any ideas to avoiding having a framed wall just for the fixture? I was thinking about the possiblity of a ceiling mount tub filler like Kohler's Laminar, since then i could locate the valve and handle elsewhere in the room (like deck mounted on an adjoining counter) and avoid the framed wall. Thoughts?

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,201
    Blog Entries
    1

    Default

    You may want to look into John Bridge's tile forum about waterproofing your tub.

    There should be any number of attractive ways of supporting a fixture in your case.

  5. #5
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    I also had some questions about whether a concrete tub could be made waterproof, but had no experience; didn't want to even bring it up. I bet the John Bridge folks will have the answer.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,401

    Default

    Kerdi could do it (keep it waterproof), but the drain is a problem; they have a prototype version for a tub, but the only current production drain is for showers. That assumes you are going to tile it. Kerdi will only work with a special thinset in drain; no clamps. Comes in either an abs or pvc version to connect to the line. Kerdi is a waterproof membrane with an attached fleece thatyou thinset in place. Overlap by at least 2", and you've got a guaranteed waterproof layer you then tile over.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    Location
    indianapolis indiana - land of the free, home of the brave....
    Posts
    4,243
    Blog Entries
    1

    Talking one small queston

    I am wondering about the wood and how it

    keeps from getting moldy over time,

    also how do you keep this clean and tidy looking


    In the links,

    it is basically something a public bath something
    like a common hot tub from what I read.

    What does it take to keep this clean after draining the tub??
    Last edited by master plumber mark; 06-30-2005 at 07:19 PM.

  8. #8
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,633

    Default tub

    If your tub is like 95% of the ones like it in Phoenix, it will only be a short time before it becomes a decorative planter. Usually after it is used a couple of times and you realize how uncomfortable it is with the vertical sides, square corners, and flat floor. If it not so much a question of repairing the valves if you put them in the concrete, but that it would be illegal to mount them below the rim of the tub.

  9. #9

    Default

    Far be it from me to abet someone who thinks Terry's tub is ugly and something that resembles a horse trough is not, HOWEVER..... I've got 60 year old concrete laundry tubs that still hold water. (Wouldn't that type of surface be a bit abrasive, if the concrete were finished rough, or slippery if finished smooth?)

  10. #10
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    Location
    indianapolis indiana - land of the free, home of the brave....
    Posts
    4,243
    Blog Entries
    1

    Talking abrasive bottom

    I thought about that abrasive bottom too

    I wasnt sure if this "hog trough' had a wood bottom

    to it or a concrete bottom.....
    -------------------------------------------------------

    it certanly isnt going to be a place where

    you and your girlfreind are going to frolick for hours in...

    skinning up knees, buttox , shoulders ect....



    I dont think this concrete box is
    going to be very appealing to the opposite sex either,

    maybe one time , but never again.....
    (unless they like it rough.)

    its certanly not going to be a "chick magnet"
    if you know what I mean..


    Terrys tub is a far , far better choice for my money..
    Last edited by master plumber mark; 07-02-2005 at 05:54 AM.

Similar Threads

  1. concrete slab no flange 3.5ID cast iron
    By bob123 in forum Toilet Forum discussions
    Replies: 3
    Last Post: 03-13-2007, 08:58 AM
  2. Cast iron to PVC for Shower and Toilet Concrete Floor
    By boverton in forum Shower & bathtub Forum & Blog
    Replies: 1
    Last Post: 01-31-2007, 01:36 PM
  3. Busting Concrete and replacing Cast Iron
    By raeiken in forum Remodel Forum & Blog
    Replies: 3
    Last Post: 09-01-2006, 05:53 AM
  4. Removing Cast Iron Flange Concrete Floor
    By Amatuer123 in forum Toilet Forum discussions
    Replies: 14
    Last Post: 04-26-2006, 07:45 PM
  5. Cast Iron Soaking Tub Recommendations
    By KorasDad in forum Shower & bathtub Forum & Blog
    Replies: 2
    Last Post: 03-21-2005, 05:35 AM

Bookmarks

Posting Permissions

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