Thinking about tile - Action Required

Well, it is funny how the mind works. We are working toward Thursday, Sep 28 for the tilers to start. We ran into a neighbor this weekend who asked about our progress, and we gave him the updates (blah / blah / blah). He asked if our floor was strong enough for the tile, and we said yeah (we think so).

Tuesday (Day 28) - I was reading about tile and floor stability requirements. Apparently, there is a standard of deflection for various types of floor coverings. The inputs to this calculation are joist size, span, spacing, and material. Well, our data puts our floor just out of the range of suitability for ceramic / porcelain.

Here is the calculator:
http://johnbridge.com/vbulletin/deflecto.pl

Immediately, this puts my mind racing for other floor alternatives, that we lost $1200 on the tile that we bought, etc.

I talked to the contractor, and he will add a beam mid-span that will be supported from below in the crawlspace. He assured us that it would be able to be completed before the tilers. This will make our span 5-6 feet instead of 11 or so.