Installing Backerboard over dry rot

I'm installing ceramic tile in a bathroom. Near the shower pan is a small (3"x4") square that is a little soft and has some dryrot from a leak many years ago. Is it ok to use a larger area of backerboard that spans this space? Anyone ever done this?
Thanks
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Not a tile man, but my guess is that if there is any flex in the backerboard it will cause the tile to crack.
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Most tile backerboards are not structural, in other words, they cannot support weight. Adding some extra, however you are planning it, won't add strength. See if you can either cut out the rot and replace it with some plywood that is supported by the joists or at minimum add some plywood under the floor to support the weak area. Use cleats attached to the joists to support the underfloor patch.

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On Dec 29, 11:09 pm, snipped-for-privacy@yahoo.com wrote:

remove the rot lest the fungi pull water from the air and extend the damage
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