Floor question

Hey all,
I am doing a tile floor in my foyer.
I know I will be over 3/4" by the time I am done (more like 1 1/4"). I am not happy with the stiffness of the underlayment.
Can I go under the crawl space and attach some 1 x's to the underneath to help stiffen things up a bit?
Once again, thanks for your help.
rik
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You might get more stiffness by cross bracing.
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Joseph E. Meehan

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Joseph,
The underlayment is plywood either 5/8 or 3/4. I am not sure. The joists are crossbraced if that is what you are telling me. If not, please explain.
Thank you for your help Joseph.
rik
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Padded room with a view
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