Flooring Tile - What do I do now?

Hi: I was planning to replace our old vinyl floor with porcelin tile. Been doing my research and worrying about the different floor heights, backerboard vice DITRA, and looking at the forums. Looked at the joists and found enormous amounts of insulation obscuring my view. So, put on some Tyvec and went crawlspace crawling. What I found may eliminate my tile. I've never seen a house built like this.:wall: The subfloor is 1x6 shiplap, at least two layers, over 3x8's on piers at four foot oc. No joists at all except for the 3x8s. Can I still put tile down, and if so, how?:thinker: I'm not financially prepared to put joists in throughout my house.

NO tile for you!:wall:

Let me guess.........you're in California right?:D If not, very close.

Jaz

No, Central Washington desert. California is our southern suberb.

Except for those damned mobile homes, every house I have ever seen had joists, however bad they were, from 2x4's at 12" oc to 2x12's on 36"oc. The best had 2x12's at 18" oc. If I had know this when I bought it, I wouldn't have bought it. But who knew, you can't see anything cause of the insulation. Now I'm stuck.

How about putting down 5/8 or 3/4 exterior plywood over the shiplap?

How does the floor feel? There is no spec for beams at 48" o.c. and no joists.

It's impossible to advise you unless you have the floor system, both beams and 1x6's tested for deflection. You may be able to get a deflection meter, or make some kind of jig to measure the deflection.

The max allowable deflection for ceramic and porcelain tile is L360, (1/360, when tested with a 300 lb. load). This is bare bones minimum quality. As an example natural stone requires L720 for joists and double subfloor.

It's possible you can still have tile, but I doubt it.

I said CA. because that's where most of the Q's with this method of building come from, it's a left coast thing!:D

Jaz

Floor feels really solid, I had no clue until I deliberately jumped up and down next to the refrig and the stuff on top of it vibrated. The frig in in the middle of the span, right next to the hot water heater. Lot of weight in that area. At this point, I believe the floor wouldn't come close to the 1/360 standard.
I'll try to find someone to test it, and if I can't, well, we're back to linoleum or manufactered flooring. I suppose I could use the tiles we purchased in the laundry room and den, that's a raised floor over a garage slab. With Murphy on my shoulder for this project, I'm going to doublecheck everything!:(

Thank you

Cal