# 18x18 travetine



## POOLMANinCT (Oct 7, 2006)

hi guys, I posted a while back & I'm doing the deed now. I demoed my bathroom. it was a tough surprise the prior owner screwed sheetrock to an old mud job. wow was I suprrised. now that the dust has settled its time to get building. ( there is plenty of work.)
the plann is to put down 18x18 honed & filled travertine for the floor. I have been doing a ton of 'tech research'. deflection etc. this is what I've done. 

1. subfloor runs on a 45.
2. putting 3/4 ply on top of sub.

this is were I start thinking, about deflection.
1. w/ 4 peopl in room a glass of water dosnt move.
2. put level on joistd through drop ceiling below, bubble doesn't move when people walk around.
3. house is seriously over built.

I want to do a good install. I'm more than comfortable with masonry work, doing it inside is a bit unusual to me.

what is ditra? antifracture membrane, do you guys recommend it. 

thanks

ray


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## POOLMANinCT (Oct 7, 2006)

forgot,
I also want to put hardi board over the ply. I will thinset it to ply.
another point of confusion is screwing the ply & cbu board. some readings say to screw into joists while others ssy not to.

ty
ray


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## Sportbilly (Oct 4, 2006)

Where exactly you're placing the level and glass of water will affect whether they show any movement, even if there is deflection. You can lift and lower each with no change in angle whatsoever.

Can you measure for true deflection? Possibly measure the height to bottom of joists in the basement with and without the herd of elephants upstairs?


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## JazMan (Feb 16, 2007)

That method isn't going to tell you a thing. Please measure and let us know; the size, type, grade, species and spacing of the joists. Also I need to know the unsupported span of the joists measuring from face to face of the supports. Measure accurately down to the nearest inch.

I assumed the diagonal boards are what....3/4" x 6"? 

Jaz


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## kevjob (Aug 14, 2006)

use ditra it is easier and better than cbu no screws and a roll weighs 10 lbs. :whistling


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## POOLMANinCT (Oct 7, 2006)

ty for the help....
here's the missing info...

- joists 2 X 10

-14 " face to f&ce (joists)

- 45 degree subfloor 3/4" x 5 "

species grade, no clue.

appreciate it.

ray


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## JazMan (Feb 16, 2007)

OK, 2x10 joists, is the spacing of the joists 16" center to center? That means from one joists to the next. I still don't know what the unsupported span is. The species and grade will be stamped on the joists someplace. If you can't find that, I'll guess.

Jaz


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## POOLMANinCT (Oct 7, 2006)

yes ,

16 center to center, haven't found a stamp yet. buit in 1954 btw...
ty

ray


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## JazMan (Feb 16, 2007)

And the span is.........? _______ ft. ______in.

Jaz


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## POOLMANinCT (Oct 7, 2006)

JazMan said:


> And the span is.........? _______ ft. ______in.
> 
> Jaz


sorry, not following... span from what to what?? bathroom is 10 X 7... pardon my ignorance 


ray


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## JazMan (Feb 16, 2007)

Span is the distance between the two supporting objects that hold the joists up. Usually the foundation wall and the center steel *I* beam. You measure from under the floor.

Jaz


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## Bill_Vincent (Apr 6, 2005)

Ray, take that unsupported span, the dimensions of your joists, and the on center spacing, and go to the following link:

http://www.johnbridge.com/vbulletin/deflecto.pl

Plug them into the appropriate places, and it'll tell you whether or not your floor will accept natural stone. The thing is that floor has to be literally TWICE as strong for stone as it does for ceramic tile.


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## POOLMANinCT (Oct 7, 2006)

span is 13ft...

ty jazman


bill v. it won't let me acess the calculator.... though I registered today. btw bill v, in my research surfing, you popped up often.. cool!

ray


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## JazMan (Feb 16, 2007)

OK, got it.:thumbsup:

I checked with my official American Wood Council calculator and it seems you have made it by a nose if everything is in perfect shape and my entries are accurate. It would help if you can get me the missing info though. 

I entered; Southern Pine, 2x10, grade #2, at 16" o.c. spacing. I kept the 'live load' at the standard 40 lb. sq. ft. but raised the 'dead load' to 20 from 10 lb. sq. ft. because of the added weight of your new floor. The results is you are at L720 up to a span of 13' 0".:clap: However...if I go to 50 lb. live load instead of 40, you are over spanned, which means a stone installation might not be a good plan. There is much controversy whether you need 40 or 50 lb. live load for residential.

I checked the deflectorator over at JB's and your joists failed for stone too, I knew it would. That calculator isn't adjustable and is very conservative anyway. More later.

Jaz


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