Cast iron bath & joist dilemma! Newcomer!

Discussion in 'Builders' Talk' started by Khal, Sep 15, 2018.

  1. Khal

    Khal New Member

    Cutting a long story short , I have rehashed a large bathroom, corridor into a bedroom and bathroom. New bathroom is c 12*5 ft, the bath [ cast iron c 40+ years old]?has been moved and runs parallel to the joists rather than across. In the midst of this work we encountered 3 joists with dry rot near the pan and basin. So these have been rectified with 3 new joists sistered, bolted, treated new tongue and groove fitted. We also made consideration for this bath to sit in the middle of two joists , given we had to keep the floor cut open due to the level of the floor and flow etc. Hey presto see pic , it’s a fair bit of and bath is not even sealed in. V Annoyed owner at my builder!!!! Who is out of the equation!

    Solutions :

    1. Build out wall to make sure bath sits on joists- lose c 5”
    2. Or run steel plates screwed across the joists and allow the bath to sit there or maybe weld into position both extreme I know!!
    3. Board up with t&g from joist to joist to spread the Weight and put a bend in the waste to allow the flow and notch out accordingly.
    4. Remove stretch of board below in kitchen and run in joists!

    NB. Tiler decided to run his hardibacker board ahead of the plumber setting the bath today!!!

    The joists are 5*4 sistered up with 5*2 with struts at 12ft span so pretty solid. The door is 30” and can be reduced to 28” although Iam about 1” spare here.

    See pics: blue lines is wear the joists are running and yellow crosses where the noggins have been put in place with ( spare c16 7*2) red circles show the obvious where the legs are barely hitting the support!

    Advice? Hope to get some good responses as new comer. I am good with calcs if someone can point me in the right direction, but issue is the joists are non standard. Assuming dead load +live load / area of bath = knm2 ? Against trada figs?

    Thanks in aniticipation .

    Attached Files:

  2. KIAB

    KIAB Well-Known Member

    Could have put down whole floor, then sat bath on 5x2 bearers, would have gave ample gradient for waste plumbing under bath.
    Last edited: Sep 15, 2018
    wiggy and Khal like this.
  3. Khal

    Khal New Member

    Thanks for your swift response and solution , this would work and spread the load.
  4. KIAB

    KIAB Well-Known Member

  5. sospan

    sospan Well-Known Member

    May want to check the waste pipe condition and diameter. Unless it is impossible to get away from it, you don't want a joint underneath the bath
    KIAB likes this.
  6. Khal

    Khal New Member

    Thanks, waste pipe is new , all fittings have been replaced.
  7. KIAB

    KIAB Well-Known Member

    Can run bearers width wise,I've even laid them length wise & fixing them to floor with timber screws through 3 or 4 joists.
    With some old baths you can't attach them to the wall,so I just bore a hole in bearer about 20mm deep, same size as the bath support foot, bath ain't going any where.
    Khal likes this.
  8. Khal

    Khal New Member


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