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Unread 10-25-2020, 01:44 PM   #23
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,205
It's my understanding the Schluter did some tests at less than industry standards deflection with their Ditra product, but found that while it worked, everything had to be perfect with no margin for error, so they, being conservative, decided to keep the status quo. That included the joists all being up to snuff without improper holes, notches, fastening, subflooring installed perfectly, and thinset coverage essentially perfect. IOW, conditions you'd almost never encounter. If you throw in a situation where you may exceed the initial loads (throw a party, move a monster freezer on a dolly into position, decide to put up a center island with a 3cm granite top, etc., that could easily exceed the design load) then all bets were off.

For lack of a better one, the test generally used is the Robinson floor test. This is a weighted roller that runs over the floor numerous times with weight added in increments until failure. The number of times and the weight then classify the suitability of the tile for different conditions from residential to heavy commercial. Now, you're not going to be driving a tractor trailer over your tiled installation, but it might need better than a typical residential rating, too when you throw in some of those outlyer conditions mentioned above. That Christmas party might just do the tile in!
Jim DeBruycker
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters), Mapei Training 2014, Laticrete Workshop 2014, Custom Building Products Workshop 2015, and Longtime Forum Participant.
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