Help with Deflection [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Marko F
02-08-2014, 03:59 PM
I am trying to figure out the deflection of my master bath floor. I have 2x12 joists, 16" O.C. With 3/4" Advantec T and G. The joists are 16' long. I used the JB deflection calculator, but does not seem to account for subfloor thickness. Also have some conflicting info from what I have read here and what Advantec says on their website. Any help would be appreciated.

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Bodie Powers
02-08-2014, 04:05 PM
What are you hearing on the Advantec website?

When you say joists are 16' long, is that the unsupported span?

What type of finished floor are you planning to install?

Marko F
02-08-2014, 04:07 PM
Bodie - yes, span from steel I-beam in center of house to exterior wall.

Marko F
02-08-2014, 04:09 PM
I already have 1/4" Hardi thin set and screwed to the Advantec, was only planning on installing porcelain, but can get a great deal on some 12" x 12" travertine.

Bodie Powers
02-08-2014, 04:22 PM
Your joist deflection is L444; to meet the minimum deflection required for the travertine you'll need to strengthen your floor structure by either sistering at least the center 2/3 of your joists, or shorten the joist span by adding support from below.

Richard Tunison
02-08-2014, 04:23 PM
Stick with the ceramic tile. You are very short on the deflection and natural stone requires 2 layers of plywood installed properly. But it's your house and money and you can do whatever you want. :shades::)