Cracked Tile Floor
Cracked Tile Floor
(OP)
I recently was called to a situation where cracks were forming in a tile floor. I inspected and found 2x8's at 16" o.c. spanning 11.5'. I"m getting typical TL/240 and LL/360 deflections, so they are coming in at a reasonable place. I was exception to get borderline to over the typical deflection limits, but I'm not. I'm seeing (2) lines of cracking each about 1.5 feet from the center of the span. They are perpendicular to the span of joists. They look very much like excessive deflection minor small cracks. I have done a bit of research and LL/360 is the tile industry standard. I see that other placed like natural stone tile request more. In this case is there anything to report back for a future remediation if the floor is replaced? Am I missing a temperature or other affect that might be causing this. The one thing of note is that I observed that there was no bridging or blocking between joists, so my only recommendation at the moment would be add bridging and blocking at supports. Do you think that would be enough to fix the issue in the future or is the recommendation additional support or joists if they want to use tile in the future and not want it to crack? Any advice is greatly appreciated.






RE: Cracked Tile Floor
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: Cracked Tile Floor
Mike McCann, PE, SE (WA)
RE: Cracked Tile Floor
Did someone use a two wheel or four wheeled dolly of some sort, with wheels about 3' (2 x 1.5') apart, to move something heavy across that floor? It seem unlikely that normal uniform loading would cause two fairly parallel crack lines across a floor system. Remember, TL/240 and LL/360 are just deflection numbers, shown over the years to provide good results for most tile or stone type flooring materials. They are not magic numbers of perfect protection for all materials or loading conditions. Smaller sized tiles might help. Reducing the joist defection might help, as might increasing the stiffness of the underlayment layers/materials spanning btwn. the joists. Blocking or bridging certainly wouldn’t hurt in improving the deflection characteristics of the floor system. You might ask a tile setting craftsman, would some sort of reinforcement mesh in the thin set layer, or a thicker setting bed help in some way?
RE: Cracked Tile Floor
I'd like to see bridging at mid-span so that you'd encourage load sharing between the joists.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Cracked Tile Floor
There may also be some sort of installation anomaly that will only be determined after demo
RE: Cracked Tile Floor
http://www.custombuildingproducts.com/media/736045...
Dik
RE: Cracked Tile Floor
Adding blocking is a good idea, as is sistering the existing joists. Sometimes I have justified sistering every 2nd joist, plus adding blocking.
RE: Cracked Tile Floor
Mike Halloran
Pembroke Pines, FL, USA
RE: Cracked Tile Floor
RE: Cracked Tile Floor
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com