Hope I got this in the right folder-
I’m a general carpenter/remodeling contractor with about 15 years experience. I installed tile in a client’s home and now six weeks later some tiles are lifting up in the middle of the floor. Here are the details:
-Modern home about 9 years old built by reputable builder.
-All-wood floor trusses 16″ deep, 24″ on center, designed to exceed L/360, according to the original truss engineer.
-Plywood subfloor, 3/4″ T&G, nailed and glued to floor trusses.
-Original tile kitchen (same truss spacing), adjacent to new floor, is in perfect condition with no cracks.
-After removing the carpet and pad I used a hammer to set any high nails. Anywhere that it seemed like the nails would bounce back and did not want to set I added screws. I also added screws anywhere two corners of plywood sheets met, just for good measure.
-I installed 1/4″ Hardie-Backer over a bed of thinset spread with a 1/4″ trowel, fastening it exactly to specs (8″ spacing, I think) with “Backer-On” screws designed for this. I made sure all joints in the backer were staggered, and none of the edges were closer than 6″ to any joint in the subfloor.
-I installed 12″ tile, also with the same 1/4″ trowel.
Now, there is a section (3’x5′) near the middle of the floor (12’x12′) that has pushed upwards. A straightedge shows the bulge to be about 1/4″ above the rest of the floor.
What would cause the floor to raise upward like this? Or else, where did I screw up?
Replies
How where the outter edge of the room finished? What the baseboard removed? What kind of gap between the tile and the wall, baseboard or whatever?
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
All baseboard was removed, joint adjacent existing floor was filled with sanded caulk.
May not be directly related to your tile failure. You say the floor trusses were rate at L/360. But, the 3/4" ply spans floor trusses spaced 24" o.c.
The plywood between the joists is probably not rated at L/360. That is much more of a problem than the joists themselves.
When reading your post, my first thought was also: Did you leave a gap around the edges for expansion? Did you use a decoupling membrane on the floor?
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Post your question over there with detailed info, and they will be able to help you.
Bryan
"Objects in mirror appear closer than they are."
Klakamp Construction, Findlay, Ohio - just south of the Glass City
Edited 3/20/2008 11:46 pm ET by BryanKlakamp
No decoupling membrane. Should I have used one? Subfloor span between edges of floor trusses is only 20.5". I hope this isn't the problem.
Why did you use only 1/4" hardi backer? Probably should have been 1/2".
Have the tiles in the bulged area separated from the backer board? Or, did the backer board come loose from the subfloor? If either is the case, then maybe the thinset did not adhere.
The backer board should have been set with latex modified thinset. As for the tiles, what does the backer board manufacturer recommend?
A bulge in the tile would usually indicate what is called tenting. That is where the tiles have expanded and there is no room for them to move laterally, so they go up. It would be like taking a piece of cardboard and pushing on the edges, and the middle starts to bow. That is why you need to have expansion room around the edges.
A decoupling membrane, such as Schluter Ditra or Wedi board also would have helped to prevent that.
Bryan"Objects in mirror appear closer than they are."
Klakamp Construction, Findlay, Ohio - just south of the Glass City
Did you not screw all the plywood down?
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Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Need more floor ? 1.25"
"Plywood subfloor, 3/4" T&G, nailed and glued to floor trusses."