ceramic tile (help)


  #1  
Old 10-12-04, 07:11 PM
Angco
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ceramic tile (help)

I am attempting to rebuild my bathroom from the studs and ran into some problems. I was able to put the shower pan liner down with no leaks. However, when I installed my cement board I only left a 1/2 gap to the pan bottom. I now need to put a wet bed down (approx 1" 1/2 thick) will this cause a problem. I was hoping that since cement board is not affected by water I would be ok? What do you think? The second problem is that when I put a 4' level on the wall it bows in about a 1/4" in the middle, can I make this up with mastic or will this not be noticeable with tile (I am using 6 x 6 tile)? Finally, Can you please tell me what I need to make up the wet bed any tricks to getting the proper slope and is the adjustable drain supposed to be able to move after the mortar dries or do I pack around it after I get the proper height?


Thanks Dan
 
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Old 10-14-04, 10:59 AM
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I'm not quite getting what you're describing with respect to the 1/2" gap between the tile backer and the shower pan, but a couple of things you said sound wrong:

1. Concrete board, or tile backer made of composite cement and fiberglass webbing is NOT water proof. Actually they don't repel water at all. Moisture passes right through. That's why 6 mill plastic is usually hung behind tile backer in general when constructing a shower or tub surround, and/or a water proof membrane is applied to create a barrier with the shower pan or tub surround before the tile is set.

2. Mastic is just plain WRONG for this application. Mastic cannot be used in wet areas period. That's because it reconstitutes and looses its adhering ability. This is a "mortar only" application, and is more complicated than just setting the tile with thinset. There's a specific set of procedures you have to go through to build a shower pan, a curb, a preslope to the drain, and joining the wall to the new pan. If you skip steps, or do it wrong without considering moisture as a problem you could end up tearing it out and starting over a few months or years down the road - and then you'll have water damage to add to the frustration.

3. You mentioned a 1/4" bow in your wall. Tear out the board and shim up your studs. Trust me this will eliminate a lot of frustration later on. If you don't want to do this, then you will have to set in place some screed strips (giant shims) on both sides of the wall that are plumb and square to the adjacent wall, and screed mortar onto the wall between the strips with a straight edge. Then use your trowel to smooth out areas around your shower valve, shower head, recess for soap, etc. This will take several days of hard work either way, so be prepared.

Ultimately I would recomend you go get a book and study up before continuing. It doesn't sound like you're on the right track, so here's an EXCELLENT source of info for what you're trying to do:

http://johnbridge.com - Check out the forum (you might see me there), and check out John Bridge's book on tile setting, etc. There's about a million people on this forum who've built their own showers and tub surrounds, and even after they FUBAR'd their installs guys here helped them fix it, and get it done right.

...and here's a book I used when I first learned how to set tile for my own projects:

http://www.amazon.com/exec/obidos/AS...336951-1141768
 
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Old 10-14-04, 06:30 PM
Angco
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Thanks for the reply. I did numerous amounts of research before I started this project and followed instructions. My shower pan liner is installed over a pre-slope. On the walls I have 6 mil plastic (and according to articles the plastic is not needed however it serves as a vapor barrier if used) on top of that is 1/2" Perma Base cement board which was recommended by home depot as well as numerous web sights (including this old house).Home Depot defines Cement Backerboard as a rigid highly water resistent glass fiber reinforced cement panel a perfect base for setting tile. Also according to this old house they recommend using mastic because it is much stickier than mortar. When I istalled the lower sheets of cement board I only left a 1/2 gap between the rubber liner and the bottom of the cement board instead of the recommended 1" (note my liner extends 7" up each wall and yes I do have a curb. The dip I mentioned is not 1/2" it's a little less then an 1/8th in the middle but the walls are square at the corners. Can I please get several replies on this since now I am really confused?????????? Thanks Dan
 
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Old 10-14-04, 07:14 PM
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Ok, I think I see what you're saying now. Sorry for the confusion. It sounded like you were going off in the wrong direction, but with your reply it sounds like you just have a few details to work out. I would bring the tile backer to the recomended height above the shower pan. Your 7" overlap sounds fine.

Also I kinda misstated when I said tile backer doesn't repell water "at all". It repels droplets, but over time the board will saturate just like untreated concrete, and the moisture will pass through. That's why the vapor barrier is there - to prevent water damage to the support structure. EVERY professional tile setter will tell you a vapor barrier is a must, or a waterproof membrane ( a roll-on type ) is also good. Now some books and Home Depot especially will try to tell you that it's optional. Yes, it is according to many building codes, but I think Home Depot is misleading, because tile backer is technically water "resistant", but it is NOT water proof, and moisture that is not in droplet form will pass right through it and collect on whatever is underneath.

BUT...I don't know what the "this old house" guys are smoking. Mastic is absolutely not recomended for these types of installations. It will reconsitute, and your tiles will fall off the wall in a couple of years. There is absolutely nothing wrong with thinset over either a mortar bed or over tile backer that has been installed correctly. Mastic is questionable in any area where water might remotely be. The only place professionals even think about recomending it is on backsplashes. I have never had problems using a modified thinset to set wall tile - even that big.
 
 

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