Here’s head scratcher. Have new house we just finished, a couple of weeks ago we noticed 3 cracked tile in the bath. It was about 8″ back from a door (no threshold) didn’t think much of it, these things happen. Pulled the cracked tile and reset. Yesterday we got a call from the homeowner, 5 more tiles cracked in the kitchen. Then last night we get an e-mail several more tiles cracked in the foyer. I was at the house last wednesday and they were not cracked. This tile has been down for over 2 months.
Floor system is engineered, Advantech glued and screwed to TJI’s, Hardibacker over the Advantech and then tile. Tile guy we used many many times with no problems till now. Could it be bad tile? Anyone ever heard of such a thing?
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Kid dropping bowling ball for fun.
Experienced this type of problem only one time. It lasted for about 2 weeks. Turned out to be seismic activity in the area. Once things settled down everything was fine. The seismic activity was caused by blasting at a local quarry. Might want to check with your local geological office.
The floor system needs to be checked to see if it can support tile. Max deflection is L/360. If the tile is natural stone then it's L/720. One more thing, is the Hardibacker bedded in thinset?
Floor system is OK, I don't know if the Hardi was bedded, I wasn't there when it went down.
It could also be that the tile installer didn't leave a gap around the perimter, which would allow the tile to expand and contract. It would require pulling off the baseboard to find out.http://www.moritzcarpentry.com
You need to find an answer to those questions if you want to identify what is causing the problems...
Billy
aul.... good floor but not good enough...the hardibacker has no flexural strength...
our tile subfloor is 3/4 Advantech....with 1/2" Advantech over it....then you can use hardiebacker or not
BTW...are the TJI's 16", 19.2, or 24" oc ?
hardiebacker is NOT a substitute for plywood.... the tile specs usually call for 1 1/4" subfloor
Edited 7/12/2009 4:58 pm ET by MikeSmith
What Mike Smith said. And - what kind of tile? Ceramic? Marble? Limestone? etc.
Jeff
Thanks for the comments,
To answer some of the questions.
16" OC for the TJI's
Ceramic tile 12" sq.
TJI span?
Not really but. How big are the tiles? The bigger the tiles the more rigid the floor system has to be. I stopped using the backer boards unless the sub flooring was less than 3/4. I use Schluter Detra or for larger or natural stone tiles I use the Detra XL. The advantage with this product is the uncoupling. Tile and floor system are not bonded to one another. Good luck!
I'm not sure that the size of the tiles has anything to do with problems caused by floor deflection.
The grout would have to take up any cracking if smaller tiles are used; however, that would be no more desirable than to have a tile crack.
The answer, IMO, is to prepare the subfloor so that there will be neither cracked tiles nor cracked grout. I am sure that if 18" tiles crack, the grout is also cracking.
Some of the products that decouple the tile from the subfloor might make this situation less of a problem, but ultimately, it is going to end up pretty much the same. The decoupling achieved with the membrane is most effective against horizontal movement. The extra fraction of an inch of vertical movement that is allowed with a membrane over, say, a 10 X 10 foot kitchen floor will prolong problems at best.
I have found that the best ways to reduce problems of deflection are:
1) Double the thickness of the subfloor to 1.5". This will not significantly affect deflection, but if the top layer is glued and screwed to the layer below, it will encourage a more spread-out deflection. Essentially, the floor will be less likely to deflect more than the tile and grout can take in a small area. I have actually tripled up the floor in a bathroom for this reason. The other advantage of this method is available if the original floor was not adequately fastened to the joists and if the joists were not properly crowned. This situation can cause some of the joists to take the load most of the time. When heavy traffic is on the floor, the floor deflects down to where the rest of the joists provide adequate support. I have also run into this problem. My solution was to screw down the subfloor on all of the joists, and add another layer of subfloor with plenty of glue and screws.
2) Add a 2X6 wall below the floor at the center of deflection. This will assist the joists in resisting movement. A supporting wall in the basement is essentially load-bearing, even if it is in the center of a room. Therefore, I place 2X6 blocking at the middle height of the wall. This serves to resist twisting forces on the studs and is probably overkill, but always works. The cost is a little extra work as the blocking is usually available as scrap after the studs are cut to fit the basement height.
3) In extreme cases, some of the studs will have to be sistered up.How can you understand God if you can't understand people? How can you understand people if you can't understand yourself?