Do we set the tub and then put up wall?

Discussion in 'Remodel Forum & Blog' started by HoneySuckle, Mar 5, 2007.

  1. HoneySuckle

    HoneySuckle New Member

    Messages:
    126
    We are taking out the tub completely and going to install another. Do we need to put it on some type of mortar?

    Also, do we put up whatever vapor barrier and wall before setting the tub or after? I am thinking after but want to make sure. Thanks!
  2. Yes. Set it in a bed of mortar, sort of a slurry that is compressible when you set the tub.

    Make sure it squeezes out good, have the bare studs marked level for the tub to know when you've gotten the tub down far enough.

    Once that tub is set, stay away from it and don't disturb it for 24 hours.

    The walls can wait for another day. Otherwise the mortar you set the tub in will start to slag and leave voids under the tub.
  3. if tub-shower, vapor barrier in walls necessary

    After tub is set tight and hard, wall material goes up on studs.

    What do you have planned? Tiled walls? If so, the backer material hangs over the tub's flange (the edge that you don't see when the walls are finished) without touching the tub. If wall material butts down onto the tub, water will soak into it whenever water gets there. That air space is necessary.

    David
    Last edited: Mar 6, 2007
  4. HoneySuckle

    HoneySuckle New Member

    Messages:
    126
    Thanks for the info.

    Yes, we are planning on using tiles. So no backer board is between the tub and studs? Good thing I asked.

    What can we do for creaking floor boards in the bathroom? We're wanting to put tiles down also. I have read a little about Kerdi, is it a good thing for me to use as far as a vapor barrier?
  5. 3 products; 3 methods. Each one is different.

    The tub goes snug against the studs, and then backerboard goes on the bare studs but doesn't touch the tub's inside. If you "fur" it out slightly, it can hang inside the tub, over the lip, but that is not absolutely necessary. Later, tiles get cemented onto this and they overlap enough to close the gap.

    A sheet of plastic can be stapled to the studs first and that can hang down into the tub, since plastic is flexible it can wrap around the edge of the backboard. That is the original vapor barrier, the way it was done for years before more modern and more expensive alternatives were available. Kerdi is good too. Wedi is good too. This last one, Wedi, is both a backerboard and a vapor barrier all in one; made of hard foam with a fiberglass and cement coating; far far easier and faster to work with than any cement-based product like backerboard or Kerdi.

    Do you mean tile the floor, not just the shower? You have to tell us a lot about the joists holding the subfloor up.

    david
  6. TimL

    TimL New Member

    Messages:
    6
    Location:
    Whitney Point, NY
    You might want to take your questions over to the John Bridge Tile forum...

    http://johnbridge.com/vbulletin/index.php

    They're very DIY-friendly and the info is top-notch.

    I assume this is a tub/shower combination, and so a vapor barrier of some kind is needed. You can read up on the different methods and requirements, including Kerdi, on John Bridge or just ask them.

    Good luck!
  7. leejosepho

    leejosepho DIY scratch-pad engineer

    I believe one of the tile sites has a load calculator (but I cannot locate it at the moment), and you need to begin there to determine whether your floor system can bear the additional weight of a tiled surface. In my own case, I doubled my floor joists for strength and renailed my decking to both old and new joists before using concrete board to begin building the tile covering.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,932
    Location:
    New England
    Yes, you need to check the floor structure to see if it would support tile. Sounds like the floor is planks. If that is true, you need to buy some deck screws and re-anchor it well, then you'll need a minimum of 1/2" plywood (all sides C-rated or better, i.e., no D sides) attached to the planks. Then, you can put down cbu or a membrane (Ditra is one) and tile. The planks may have plenty of acutal strength, but they change size too much between seasons - you need the more stable plywood on top to provide that stability. There's a deflection calculator over on www.johnbridge.com. Use that to determine if the joists are okay for tile.
  9. walking on the floor.

    the deflection is a slight sag, and THAT is what can put hairline cracks in your tiles. Deflection happens when people walk on the floor. To be precise about it, deflection is not because of the weight of the tile itself.

    David
  10. HoneySuckle

    HoneySuckle New Member

    Messages:
    126
    We have linolieum on the bathroom floor which is a medium sized bathroom, about 7 1/2' x 7 1/2' and has 8' ceiling I believe.

    The creaking drives us nuts at night. Before we put down tiles on the floor we would need to take care of the creaking but since the area with tiles won't be so big would the weight be an issue? There is a 54" vanity and a toilet then the tub which is Americast by A.S.

    We need to use Ditra on the floor?
  11. your joists. How long, how "big".

    honey

    What is a joist? Find out everything you can about the joists under this particular creaky floor.

    Whatever sections of all the above posts you don't quite understand, discuss here. :)

    david
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,932
    Location:
    New England
    The size of the floor you are going to tile is nearly irrelevant, it is the support under it that determines how far it can deflect, and whether it is strong enough to survive without cracking things..
  13. the_slowpoke

    the_slowpoke New Member

    Messages:
    7
    Do the Walls last..but vapor barrier first

    Hello. If you are putting the tub against an exterior wall, make sure you insulate and vapor barrier before you install the tub including using acoustic sealer between the floor and the vapor barrier. After that, install your tub with your mortor and let it sit at least 24 hours as someone else suggested. When you do your walls, it's better to use a concrete board rather than drywall everywhere you want to tile. This is because the drywall may absorb some of the moisture from the dry-set mortor that you will be using for your tiles and leave you with a less than adequate bond. Bring the concrete board down to where it just touches the rim of the tub, but not on the metal edge that you use to fasten it to the wall. When you tile, fill the space with dry-set morter, which is water resistant, and tile right down to the tub except for a normal space for silicon. Some people like to use grout to finish right down to the tub but I prefer silicon for that last edge as it is flexable and with people getting in and out of the tub, water load, etc, some flexability is always a good idea. As far as the floor goes, you can use 1/2 inch to 5/8 inch plywood to stiffen things up, but again I'd prefer to use the concrete board and a product like Ditra because the plywood would tend to absorb moisture from your dry-set and weaken your tile bond.
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,932
    Location:
    New England
    Thinset on ply, drywall, or cbu can all be done without problems. In fact, cbu can suck moisture out of the thinset giving you a poor bond worse than ply or drywall. Each has their place, and using the proper thinset and mixing it accordingly will produce a fine, long-lasting result.

    Do NOT use drywall where it can regularly absorb moisture. It will NOT be damaged by the moisture in thinset during the install process, but will if it sits in moisture on a continual basis. This makes drywall unacceptable in a tub shower surround below the height of the showerhead (the area considered wet). Drywall in a dry area can have tile installed without problems.

    Plywood can accept a highly modified thinset and produce an acceptable tiled surface, but most people don't do the prep right, and it often fails. It won't if you follow ALL of the steps EXACTLY. There is more leaway if you use cbu or a membrane on top of the plywood, so most people do it that way. Both methods are approved by the Tile Council of America (TCA) which is the basis of most local codes.

    Except in locales where they haven't updated their code, greenboard is no longer acceptable. There are better products.
  15. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Creaking floor boards are not a satisfactory base for ceramic tile. You usually need a double layer of plywood. If it moves enough to creak, then it may not be stiff enough to support ceramic tile without moving and cracking the tile.

    Smaller tiles will survive better than large ones.

    Go to www.johnbridge.com , read it a bit, and then ask some questions.
  16. mold grows on the paper.

    Drywall has paper holding it together. Greenboard is the same; it is more rigid when wet, but it still grows ("harbors, fosters") mold.

    Better drywall products may not turn out to be better, since their big new claim has yet to be tested. They claim to inhibit mold growth.

    Hmm. I'll believe that in 30 years from now.

    David
  17. HoneySuckle

    HoneySuckle New Member

    Messages:
    126
    I wonder why they used two layers of drywall? We were very lucky in that there is no moisture damage after all these years.

    Will be checking those joists and reporting back. I looked on John Bridge's site but some of the explanations there are way over my head, sorry:( Thinking you all are going slow enough for me to understand so here I will stay for a bit.
  18. comprehending builders' mentality

    two layers of drywall? Well, 99.9% of builders don't care about giving you an inch more space to move around in; they have far more important concerns.

    A second layer enabled them to fill space (volume) to get the wall positioning exactly as necessary. Another "advantage" that they could use to explain it to the customer who might happen to walk by as it was being built and ask about it, is that the wall sounds more solid when bumped into.

    The cost of building materials is not the big factor. It's all in the measuring and cutting, time spent discussing and deciding where to place things (within an eighth of an inch) and time spent doing (and redoing), and then finishing and making it look good. Time spent on operations, not cost of materials.

    I'm glad you are going to tile your bathroom, and do it yourself too. You decide how you optimize your space as you wish, and don't have to give in to a professional whose interest is in making every hour count enough that you won't complain later that you paid hundreds just for talk and no action. Construction oriented people don't feel comfortable charging for talk, not like architects or interior designers. My experience. From what I have seen.

    david
  19. HoneySuckle

    HoneySuckle New Member

    Messages:
    126
    David, I was reading about Kerdi and wondering if we should use that in the shower area where we are tiling. My understanding is that you put this barrier up on the studs and then put Hardi backer board?
  20. it's an option. It goes on top of drywall.

    david
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