To tile or not - Deflecto says L380

[Tbakes]

Hi all, first time poster, but have lurked for a bit.

Background- I've been reading John's book and finished the chapter on subfloors. I previously tiled a 150 sq ft kitchen in my last house. New (old) house has vinyl in the 2 bathrooms on the main level that I want to replace with tile. The level under (daylight basement) is finished with no access to the joists directly under the bathrooms. The joists are 2x10s, 16" OC. The subfloor is 3/4" ply that looks to be in good shape. The house is fairly modern construction, built in '89. The joists are ~14'6" from perimeter to the steel I-beam that runs down the center of the house. Both bathrooms are located on one side of the house (eg on one side of the I beam right next to each other).

The deflecto says I have an L380 deflection and am good for tile. Floor feels solid, but have not yet done the "jump test".

Prior to John's book / finding this forum, I had planned on tiling as I did in the previous house - using 1/2" Durock CBU and modified thinset. For these baths, because they are small, I will probably use 6x6" tile (unless larger would look ok - baths are maybe 5' x 5' and ~7'x5').

So, should I go for it? Any other advice? Are any of the tiles offered at lowes (Rialto?) decent, or should I go to a "tile store"?

Thanks!

[jay f]

If the deflecto says it's ok then your JOIST structure is good to go. Now we need to address the deflection BETWEEN the joists. A layer of 1/2" ply would do nicely here, then CBU (or Ditra) then tile. As for size of tile, it's a personal choice, I prefer larger tile. IMHO, the biggest secret is to pick a tile that you like, regardless of size. With your structure, ceramic is a good choice. No stone will work, sorry, although a porc lookalike will.

[bbcamp]

At 14'-6", your joists are a bit overspanned for tile, but I don't think that will be a problem, so long as the joists are in good condition and are not chopped up for the plumbing. Other structure in your house will help stiffen them.

3/4" T&G plywood is more than adequate subfloor for ceramic tile, no matter what underlayment you choose. Again, the plywood has to be in good condition, not rotted, etc. Of course, more subfloor is better, so if you can afford another 3/8", then add 3/8" plywood. You can use Ditra as your underlayment to save height.

[Tbakes]

Thanks for the replies so far...

Last night did the jump test and remeasured spans. The joist spans are actually 13' unsupported, and the subfloor is 5/8", not 3/4". It looks like I will be doing another layer of ply. Is 1/2" ply fine, followed by what? The floor adjacent to the baths will be 3/4" oak, so I'd prefer not to have too much build up. Should I go CBU or try to get my hands on some Kerdi?

What about transitions to the HW? MY mother-in-law has nice "brass" strips where her new tile floor meets up with her HW. Where might I get those? How do I handle the height difference? Anyone have a good source to get these supplies?

As for the jump test, the floor moved a bit, but seemed pretty sturdy. I think it should be fine especially with the additional ply.

-Tony

[bbcamp]

Tony, use 3/8" plywood and Ditra for your underlayment. With 3/8" tiles, your height difference will be less than 1/4".

I think a tapered transition strip finished to match your hardwood flooring will look better than a brass strip. Your hardwood supplier should be able to make one for you, or you can make one yourself.