sub-floor prep

[harum]

Hello, I have a question about floor prep for regular travertine tiles. I had a linoleum covered kitchen floor flush with the adjacent hardwood floors in a 60 year old house. I removed the linoleum and most but not all linoleum glue with felt. Underneath the linoleum is what looks like 3/8 in. plywood board sitting on diagonal planking. It turned out that the hardwood floors are also only 3/8 in. thick sitting on the diagonal planks (this was why they are the same height as the kitchen floor) -- see the photo:



I am not clear on the following:

Is there a sub-floor prep option that would somehow keep the new tiles at about the same height as the hardwood floors?

Can I count the 1'' x 6 '' planking layer over the joists towards the minimum thickness for a sub-floor to be safe for tiling, which is suggested to be at least 1 and 1/2 in.? (Here is the math: 1 in. planking + 3/8 in. plywood + 1/8 in. thinset + 1/4 in. backer board = 1 and 3/4 in. -- enough thickness).

If nothing else works, Would (1/8 in. thinset + 1/4 in. backer board + 1/8 in. thinset + 3/8 in. tile = 7/8 in.) a kitchen tile floor that is 7/8 in. higher than the floors in the areas around be safe, practical and not ridiculous?

I have no experience in floor prep and would greatly appreciate any suggestion or a reference to a website, a book chapter, or other people's experience that could help answer my questions.

Thanks in advance for your time, h.

 

[FloorMaven]

Can I count the 1'' x 6 '' planking layer over the joists towards the minimum thickness for a sub-floor to be safe for tiling...

The joist system carries the load.

http://www.johnbridge.com/vbulletin/deflecto.pl

 

[harum]

The joist system carries the load.

Yes, thanks, I know that much. The question is if the joists and the rest of the floor underneath the kitchen is strong enough for an extra layer of tile...

 

[FloorMaven]

Yes, thanks, I know that much. The question is if the joists and the rest of the floor underneath the kitchen is strong enough for an extra layer of tile...

That's why I posted the deflecto link. Insert your data and you'll have your answer.

 

[harum]

Thanks. I also had a specific question about floor prep... Can I add the thickness of the diagonal planking to the 3/8" plywood and 1/4" backer board to get the desired 1-1/2" support for the tiles?

 

[FloorMaven]

Thanks. I also had a specific question about floor prep... Can I add the thickness of the diagonal planking to the 3/8" plywood and 1/4" backer board to get the desired 1-1/2" support for the tiles?

Can you post a link to the thickness spec you are referring?

 

[harum]

Can you post a link to the thickness spec you are referring?

I don't have links for that. My question is Would 1"x6" planking, 3/8" plywood and 1/4" backer board over joists be acceptable subfloor for tiling?

 

[FloorMaven]

I don't have links for that. My question is Would 1"x6" planking, 3/8" plywood and 1/4" backer board over joists be acceptable subfloor for tiling?

Short answer- probably not, stone requires a subfloor system twice the stiffness of ceramic tile.

 

[harum]

Short answer- probably not, stone requires a subfloor system twice the stiffness of ceramic tile.

If the joists are strong enough according to deflection calculation, what is missing then? Something that gives strength in between joists?

 

[FloorMaven]

Something that gives strength in between joists?

Yes...backerboard adds no strength to the structure...3/8" ply is worthless. Pull that out, add 3/4" CDX and ditra.

 

[harum]

Yes...backerboard adds no strength to the structure...3/8" ply is worthless. Pull that out, add 3/4" CDX and ditra.

I read the same thing about backer board and 3/8" plywood... But what about the diagonal planking over joists (as in photo)? It is 1 in. thick and got to be good for something, because it is solid wood and in a good shape. It got be stronger than CDX etc.

 

[Floorist]

Most tile pros will tell you not to leave the diagonal planks.