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Old 03-05-2011, 07:43 AM   #12
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Join Date: Sep 2010
Location: NY/FL
Posts: 599
I used the 719 number the op qouted, As his drawing showed 2x10s nominal and his unsupported span, I just ran that back through the defleto to see what variable (16"oc) he had used to get 719.

The Op has since conformed that.

ImO as I said, the deflection movement is insignificant when you convert the deflection number to actual inches within 18" of that beam. I often see people do long span ijoists floors not realizing a normal deflection number can easily result in a 1/2" of defection movement which I have always felt is a weakness of just using a defelction number in judging suitability for stone or tile alone. Here we have somewhat the opposite as he is working ionly within a foot and a half of the beam.

With less than 3/16 of an inch at midspan of calculated fully loaded deflection, uplift is really pretty non consequential also.
I mean we are talking about a relatively stable floor. It's all relative. 719 on a 10 foot span is a whole lot more stable at the splice than 719 on a 20 foot span. The uplift on a 10ft or so span even with 3/16 of max defectionI is tiny. (a couple hundreths of an inch) just don't see the big iissue. IMO either shave the hotspot or cut the tail and good to go
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