This discussion, "Stone in a bathroom", in Ceramic and Stone Q&A (part of the category Do-It-Yourself & Consumer Support), begins, "I am doing a consultation on a bathroom, look at the pic and give your comments please...."
Also although it looks like they attempted to up the deflection rating did they actually succeed?
Looks like a couple of the sistered joists have been notched.
How was the sistering done? Glued and screwed/nailed, No joist hangers on the original joist.
What is the span and the height of the joists? Any support walls under that header joist or any of the others?
As Danny pointed out there is alot of weight on that floor but also looks like a plaster ceiling which also adds weight.
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Scott
Last edited by stullis; July 15, 2008 at 05:36 PM.
Oh there's more to it than meets the eye. I'll let Roger fill in the details when he gets ready.
I am curious to known something that Roger didn't mention earlier today when we talked. This is a second floor bathroom. You can see the ceiling below is plaster lath and plaster, obviously.
My question is:
Is the ceiling down below also showing signs of stress and destruction?
Roger I'm going to stand fast on my earlier assessment of the backboard that was used. Those cracks look to me like they may have came from someone walking on the floor when it was lit-up. I'll shut up now and see what others think.
X marks the cracks where the floor sank and cracked the tiles. Good questions Scott.
Double plywood subfloor?
Backer board? Installed correctly?
Antifracture membrane used?ank and cracked the tiles.
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I would have to suspect that this is more of a substrate problem rather than structural. IF the plaster ceiling below shows no sign of cracking or damage.
The thing about the sistered joists that makes me wonder though, is the top left pic. The notches, and the fact that the left end of the sistered joists don't seem to be resting on anything, and are cut short. Where is the support?
Having said that, I still tend to think that the cracks seem to indicate more of a substrate issue IMHO.
Need more input Roger!
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Sorry, but I'm going to disagree with everyone concerning the deflection of the joisting. That cracking, if you notice, is occuring in UNgrouted tile. I have to agree with Bud-- that looks like someone might have stepped on cement board that wasn't fully supported, or maybe someone screwed up and didn't end the subfloor on a joist? I don't know. But the joisting or the strength of the structure has nothing to do with this, IMHO.
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After opening all that up they went in with 3/4 T&G plywood, glued & screwed.
1/2 inch Wedi board set in thinset screwed down per spec.
Then they put in wires for a Warm Tiles heating system.
Now they needed 5/8 to meet other areas so they used two pours of CBP Level Quik RS. Primer--pour SLC--primer--Pour SLC--dry overnight--primer and set the limestone tile.
They were behind schedule as they had the carpenter coming in, so they covered the floor with rosin paper and plastic and did all the trim, cabinets and paint. Somewhere in there they fired the heating system to check it and the next day they saw the hairline cracks. They say the heat was only raised 3-5 degrees to check it.
Now Wedi, Custom BP, and the stone people are all denying any responsibility.
I put a level across the floor and then brought in 800# of weight and there was 1/64 of deflection, so that is not an issue. There is no cracking of the plaster on the lower level ceiling.
Sorry, but I don't see the heating system as being the culprit. I'd say that's just bad timing. The reason I say that is that for the heating system to crack that floor, the grout would've had to have been applied already, to give the floor some kind of surface tension, so that when the heat expanded the floor materials, there was no where for the tile to expand, which would cause it to crack. That's not the case here. Each individual tile could expand into the surrounding empty grout joints. This is the same reason I don't believe it was deflection of the structure.
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In my conversation with Roger I suggested the WEDI may have been a contributing factor. WEDI is rated for floors BUT at what temperature? The WEDI was to serve as a tile backer but also a thermal-barrier for the heat is my guess.
1. What happens to the plastic foam in the WEDI when it is heated. WEDI possesses a particular compressive ability (I have no idea what that is) but at what temperature. Those floor-heat products have the ability to raise the floor temperature to around 84 degrees fahrenheit. Does this temperature-rise have an effect on the WEDI and does it reduce its compressive rating?
2. Is WEDI a suitable underlayment for an SLC product? I have worked with a lot of WEDI but frankly I would never use it on a floor with anything smaller than 12" tiles and certainly not limestone. In the past I have laid WEDI on the floor to cut it for a wall application. My knees always left an impression in the WEDI, ALWAYS.
3. Now that I have seen the photos...
I also suspect the cracks I see radiating from a central point could be from a ladder. A ladder with a two or three hundred pound workman on it. Had the tile been grouted the cracking may have never occurred. (???)
I can see where WEDI and CBP and the stone supplier would be playing dodge ball, and I don't see where any single product has contributed to this problem. I think the main contributor and the person to point the finger at is the person that designed the layering of the specific products used. Who specified the technique used?
Tile floors absent of grout should never be traversed for any reason and especially never worked on or over until the grout is installed. Who gave the go-ahead to allow subsequent tasks by other trades to be performed before the tiling was complete and the grout was installed?
Absent of any additional information those two decision-makers are where the blame falls in my opinion.
1) No double layer of plywood.
Wedi or any CBU thinsetted down does not qualify as a second structural layer.
2) All tile that is going in over infloor heat should have an antifracture membrane as well.
3) Working on a tile floor with no grout is dumb and on an ungrouted stone floor is even dumber.
Take your pick.
3 is the most likely cause of the cracking, closely followed by 1.
As Bill pointed out without grout the floor probably wouldn't have had the stress yet for infloor heat to have caused that. 2 would have happened later.
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