Need Help with installing hardibacker

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by LadyDIYer, Jul 1, 2008.

  1. LadyDIYer

    LadyDIYer New Member

    Messages:
    3
    First of all I would like to say thank you for this forum! I finally found a place where it seems like the advice is knowledgable and considerate!

    I have read some previous threads about this. I ripped out the old sheetrock on my walls around my bathtub. I had a plumber come out and plumb for a shower/bath combo.

    I had mixed information from people I know, building codes, internet sites, the hardibacker site instructions and Home Depot. I followed what I thought was best and realized I made a few amateur mistakes. I am someone who follows the instructions as written and I don't have any of the common knowledge that some DIYer have.

    I screwed up the 1/2" hardibacker onto all of the studs, making sure to put a screw every 6". However, in one place the stud is closer than 16" and on the other side, further than 16 ", the builders in 1978 couldn't measure I guess.... It is kind of in the middle on the far right away from the shower head. I made sure to secure it to all the studs vertically. It feels pretty secure and I am planning on screwing back up the same way after I take it down and do it right.

    1. The tub flange is about 1/2" away from the studs on one side and a little less on the other. The tub appears to be in there straight, just one side has more of a gap than the other. I was told to have the hardibacker overlap the flange and when I screwed on the hardibacker it of course bowed out at the bottom.

    Now I have been told to cut the hardibacker to just above the flange and have the tile overlap the flange. (rather than use furring strips all over the place with multiple layers of furring material which no one seemed to know what I should use if I did! Also, It would make the shower wall 1/2" off from the rest of the bathroom walls!)

    I also saw that the moderator on this site said on a previous thread that the hardibacker could be cut at the flange and the tile extended down. I am using 6" tiles.

    Is this really okay to do and how far should the tile overlap the flange? (how close should the edge of the tile be from the top of the tub? I was guessing 1/8"????

    2. I did not put a moisture barrier between the hardibacker and the studs. I read on several advice forums that roofing felt may cause mildew under it next to the studs. Is this true? I also read that you don't need the polyvinyl (is that correct verbage for the plastic vapor barrier?) or any type of moisture barrier under hardibacker unless you are creating a steam shower. I am making just an ordinary shower with a shower curtain above my existing tub.

    From this forum and my gut....I am thinking I have to take down the hardibacker and put up a moisture barrier, but I am not sure what product to use. I understand that you have to have the moisture barrier extend down in front of the tub flange, but what about up top next to the drywall near the ceiling? Do I tuck it in behind the drywall at the top or just cut it off at the top edge of the hardibacker?

    3. I used the correct hardibacker screws, but the screws would not sink in. My friend said it is because my drill doesn't have enough torque. He said that he can screw them in with his drill and make them countersink. Is this what is going on? How far should the screws countersink? Otherwise, I think the tiles will not be able to be on there flush to the wall right?

    4. After I screwed in the hardibacker next to the drywall, the drywall is not flush with the hardibacker. The people who have looked at it say the drywall is the same thickness as the hardibacker. Then why is it not flush? The drywall sticks out by about an 1/8".... I was going to put furring strips up to begin with, but then the hardibacker would probably then stick out! Home Depot didn't even know what furring strips were by the way! I read instructions that said to put up 1/4" furring strips, that would make the hardibacker above the sheetrock! Is the difference in "flushness" going to be made up for by the thickness of the mud under the tiles? My gut says no....

    5. I know that once I get the moisture barrier up and screw the hardibacker in place and everything is good to go, then I will put the joint tape up with thinset.

    Do I need to apply thinset in a special way over the screws? I read something about that in the threads and didn't understand exactly what that entails.

    6. I am not extending the tile onto the ceiling, but plan on having it stop at the ceiling, however the hardibacker at this time stops just above the shower head. I am taking it down and putting up a moisture barrier most likely....should I cut the sheetrock to the very edge where the ceiling and wall meet and install hardi all the way up to the ceiling?

    7. Last but not least...A tile question....I was told by the home depot guy to apply this type of varnish to my decorative trim, it is a tumbled stone and glass tile design. He said people usually put it on after it is put on the wall and grouted in. He said it would be easier if you put it on first and you can avoid getting the mud into the millions of tiny holes in the tumbled rock tile. Well, he put some on one of them at the store to show me and a few hours later at home, it was still wet and the adhesive that keeps the tile on the mesh had dissolved from it and the tiles were coming off and got jostled out of position. It stuck back to the mesh after it dried. I am thinking that if I put that stuff on the tile before putting it on the wall, it may make some tiles come loose after I put it on the wall....What are your thoughts? I am thinking I need to just wait until after the tile is grouted and dried set before I apply the color enhancing sealer...It is Miracle Brand Seal and Enhance.

    I really want to pick back up this project and finish, but I have been kind of wary of it....I want to do it right. I haven't been able to rely on anyone for advice.

    I really appreciate all of your help with this!

    Thanks in advance!
  2. gtrjunkie

    gtrjunkie New Member

    Messages:
    8
    I am not a pro but have done my own tub/shower similar to what you have. I only hung the hardibacker down to my tub lip, not over it, then used 100% silicone between the top of the tub lip and the bottom of the hardibacker. The tile then goes over the tub lip to 1/8" above the tub, then silicone the gap. I shimmed out the side walls with 1/8" pegboard cut into 1 1/2" strips to better match the drywall. I also did not use a plastic vapor barrier under the hardibacker, but I did use Redguard on top of the hardibacker. Hardibacker only up to the shower head is fine. You can still go ahead and tile up to the ceiling.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,132
    Location:
    New England
    You want a vapor barrier either behind the cbu or on top of it. RedGard is a paint on waterproofing. There are some advantages to the surface treatment, but either works. Yes, if your drill is wimpy, you'll have trouble countersinking the screws. The square drive ones make it easier to do without spinning the bit.

    Hardie is slightly thinner than 1/2", but their 1/4" stuff is 1/4". This normally isn't a big deal since you often want the tile to overlap onto the drywall, and if it's only a small distance, minimal thinset and the thinset that's under the rest of the tile will then let the tile sit flat.

    The gap at the tub at 1/8" or so is good. Check out www.johnbridge.com for great tiling help.
  4. B2CHR

    B2CHR New Member

    Messages:
    35
    Location:
    Central NC
    Yes you need a vapor barrier. I use 6mil poly under the cement board. I lap the poly down over the lip of the base and put some silicone caulking on the lip and press the poly into it. Cement board next, with a small gap above the lip. I have found that much easier to nail up the CBB with galv ring shank nails than to use screws. I do add a few screws here and there but for the most part I nail. When I do floors I all ways use screws though. Let the tile go over the lip with a small gap to caulk. Don't worry about the 1/8" difference from the CBB to the drywall. The thinset will fill up the gap. Give the tile a few days to dry good then apply the sealer.

    As for question #7, Put the thinset on the wall, not the tile sections. With the "meshed" tile pieces you halve to be careful not to squeeze the thinset through the pieces or when you grout you will run into problems. I will set a section of tile and press each piece into the thinset. The ones that fall off the section before I set it I just press them into the thinset one at a time.

    Good luck.

    Randy
  5. LadyDIYer

    LadyDIYer New Member

    Messages:
    3
    Thanks! And then again more questions!

    Okay, that sounds great. I don't want harmful fumes in my house because I have kids, so I will go with the poly. It just sounds better than the roofing felt. One last question....

    How do I attach the poly to the studs before I screw back up the hardibacker? Do I glue it to the studs, have someone hold it up there while I screw in the hardibacker, or do I staple the poly to the studs?????

    Thanks! Carla
  6. gtrjunkie

    gtrjunkie New Member

    Messages:
    8
    staple it:)
  7. B2CHR

    B2CHR New Member

    Messages:
    35
    Location:
    Central NC
    Yes use staples and a few other suggestions.
    Thinset: I use premixed thinset for the walls. I use this for my joints as well. I do my corners first with mesh tape and let this dry. As for my up and down joints I mud them as I set my tile to keep from having a hump in the wall that will bow out my tile. I mesh tape them and apply thinset then set my tile. If you have grout lines larger the 3/16, use sanded grout and spacers to hold the tiles in place as you work up the wall. The first (bottom coarse) needs to be level even if the base is not. Start with a full tile at the lowest point and cut as you need to.
    I start with the back wall by finding the center point and work both ways.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,132
    Location:
    New England
    Unless the area is dry, DO NOT use pre-mixed so-called thinset (it is really mastic). Thinset is a cement product, so anything premixed CAN"t be thinset, or it would harden in a bucket. Real thinset isn't that hard to mix or use, and is much cheaper - plus, it will work properly in a wet area, where the pre-mixed glop won't. The pre-mixed stuff will soften and can wash away. It stays soft in the bucket because it can't get any air...on a big tile, it can take months to dry out too, causing grief. About the only place it is good is a dry area with small tile, so there are lots of places for the moisture to evaporate and that moisture doesn't have to go far.
  9. LadyDIYer

    LadyDIYer New Member

    Messages:
    3
    Well, I already have the stuff you have to mix yourself and I think it is the right stuff. I always try to use the best materials, I found that you make less mistakes that way!

    Thanks so much for all of your help! I can't wait to get back to work on this project! I will post later and let you guys know how it went.
  10. B2CHR

    B2CHR New Member

    Messages:
    35
    Location:
    Central NC
    Learn something every day I guess. Have used the premixed for years on wall sections with so far no problems. Largest tile used in shower/tub is 6x6 though. Had to go back and install a new soap dish in a shower unit I did about a year ago and it was tough to get out the old tile for sure. Mastic was rock hard under it. I all ways use the dry thinset for floors. Under the backerboard and to set tile which is most of the time 12x12 or larger.

    Just mix it well, no lumps, let stand and remix. I use a large drill, big paddle/mixing bit (used for mixing up drywall mud). Quick and simple.

    Good luck and let us know how it goes.

    Randy
  11. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    Kerdi

    If you don't want to take down the backer board to put up poly, an alternative is to put Kerdi over the Hardi. I would use Kerdi anyway, it stops water from ever getting behind the backer board. It is attached with thinset. I've heard you should keep the surface of the Hardi plenty wet (with a spray bottle) if putting on Kerdi.
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