Framing and Sub-Flooring - subfloor/joist question/feeler

First of all keep in mind that this house is about 75 years old and was built by farm/field workers.

I am going to be laying some 13" ceramic tile in my moms house, while in the process of removeing the old flooring I found that the all the floor joist in the front half of the house were just floating(I knew they were already due to the bouncing) and are on aprox 20" centers, they had just used bricks to hold some of the floor up in the middle and now the bricks have settled into the dirt below. I will be replacing the all of the subfloor and I planned on using 2x10 with 3/4 T&G plywood on top of them, the span will be just under 12'.

I am wondering what you guys think the mimumum spacing should be between the joist, will the 2x10s be enough?

Some will tell you 16" on center. I would put them 12" on center. It really gives your floor alot more strength. Good Luck

The Amazing John Bridge Forums Deflect-O-Lator :-) (http://www.johnbridge.com/vbulletin/deflecto.pl)

floor joists for tile - Google Books (http://books.google.com/books?ei=8h0KSqSpLKTgtAPf5ezhCA&ct=result&q=floor+joists+for+tile&as_brr=3&spell=1&oi=spell)

Be safe, G

thanks guys for the info, I guess I will use Jack the Contractor's advice and go with the 12" centers, even though GBR in WA's calulator link said I would be fine with 16" centers I figure for the extra cost it will be worth the peace of mind. Thanks again guys.

I liked to ask another question

What size screws should I use to screw down the concrete board to the subfloor prior to laying my tile?