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Unread 10-25-2004, 11:31 PM   #21
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Join Date: Jul 2001
Location: Boerne, Texas
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I merged your new thread with the previous one. Please keep all your questions for this project on this thread so anyone who wants to comment will be able to follow the history. Your thread will pop up to the top of the queue every time you make a post to it, no matter how old it gets.


Would you please invite your GC to come by here and talk with us?

Tearing out everything down to the subfloor is a good start. Adding two layers of CBU makes no sense at all. He is obviously unaware even that CBUs have no grain and it makes no difference which direction they are laid - they still don't count appreciably toward the strength of the subfloor, although common sense recognizes you gain something. Why would he go to all the trouble to correctly install two layers of CBU instead of adding a sufficient second layer of plywood and then an approved substrate? That's if, in fact, any CBU manufacturer will specify a correct method for that second layer - but, hell, first you gotta get one to approve using their CBU over that joist spacing at all.

Try to 'splain to him that he needs a subfloor that meets the 1/720 deflection standards between the joists before the installation of a tiling substrate, and the substrate hasta be approved for the application. If you have joists with a three inch wide top chord, that's a deflection of no more than .022 inches with a really, really fat guy standing on one foot right inna middle. That's a very stiff floor, and he ain't gona get it with only one layer of 3/4 plywood.

And I think I still had a question about how y'all determined the L/1000+ rating on that joist structure.

I think you're still being led down the primrose path, Tom. Don't go.

My opinion; worth price charged.

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