Hi all!
Can ceramic floor tile be installed over trusses with plywood decking [plus cement board/durock] – without worry of cracking the tile or grout lines? The house is 4 years old.
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We want to install tile over an L- shaped area of approx. 45’ x 35’.
Work associates have all experienced failures…so am afraid to proceed.
Do we have a chance, or do we have to stick to hardwood? Thanks for any suggestions/ words of experience.
Replies
Depends on the trusses and the decking. If the trusses are stiff enough, and the decking is stiff enough, sure. Tile usually wants a deflection limit of L360. This is a pretty common number in most modern construction.
Mike Hennessy
Pittsburgh, PA
I think it depends on the thickness of the subfloor and/or the spacing of the trusses.
Using a 16" O.C. truss spacing is generally recommended for tile, frmo what I've seen.
What Mike Hennesey said is just about absolute.
See if you can fine any of the engineering data that came with the trusses when they were delivered.
If not, you'll need rather extreme measures to determine if the deflection is less than 1/360 of the span.
And the L360 number is good (usually) for ceramics. For travertine and other stone, you'll need L720.
Politics is the antithesis of problem solving.
The trusses are 16" OC, but, am still looking for the engineering data. The decking is 3/4" interlocking plywood.
What does "L360" mean for the tile? Is this a designation on the box? Does it refer to the thickness?
Also, we were told the installation layers are as follows:
1) trusses
2) 3/4" plywood
3) leveling compound
4) durock of cement backer board with 56 screws per 3x5 sheet
5) taping of seams
6) leveling compound
7) Mastic & Tile
Is this accurate?
Thanks for all your help!
<>What does "L360" mean for the tile? When we've talked about "L360", we are talking about the amount of deflection in the finished floor system. Technically, if any part of the floor rises or falls more than 1/360 of the rising/falling area's span, then tile is a no-no.Example (at least as I understand it. If a very heavy object is placed 36" away from a point which is supported by foundation...... And the floor under the heavy object deflects (sags) by more than 0.1", then that is more than 1/360 of the distance. (Since 36" divided by 360 = 0.1, and since there is more than 0.1 deflection, no tile.)I'd be a bit skeptical of a floor system that only had 3/4" of plywood -- but since I haven't seen or walked on the floor......... And note that the durock won't help with deflection. I would prefer 1-1/8" plywood minimum.Also, in this situation, I would absolutely insist that mastic not be used. As mentioned by another poster, you want to use true thinset mortar, with the latex additive (Thinset with latex is WAY more flexible than mastic, or thinset without it.)And use the latex admix for the grout too -- for the same reason. (It also usually has a mildew preventative in it -- a good thing in humid climates.)Politics is the antithesis of problem solving.
I installed tile over a large area 7 years ago. I have not had any problems. My house is 16" O.C with two 1/2" layers of plywood. I followed the direction to the tee installing the 1/2" hardi backer. Use thin set under the backer board and add the latex additive ( I think it is called mega bond). Once you have installed the backer you will feel the floor stiffen quite a lot.
If the trusses are 16" O.C. I'd say yuo're probably in good shape unless the trusses are grossly overspanned. Can you tell us how deep the trusses are, and how far they span between bearings? ie: They're 12" deep, and it's 16' between the exterior wall and a support beam, or something like that.
Can you get cavities in your dentures if you use too much artificial sweetener?
Jump up and down on the floor. If it's bouncy, don't tile it. If it's good and solid, you're good to go. Use latex modified mortar and grout to be on the safe side. What size are those tiles? The smaller they are the more flex they'll tollerate.
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