Subscribe or Renew Membership Subscribe Renew

subfloor suitability (for tile)

tuanj's picture

I have a 80 ft2 bathroom floor to do (my own) which currently has only a 2X6 T & G fir subfloor. It is over-nailed but some cracks have appeared over the (13 yr) life of it; I have planed down the high spots. Can I get away with putting hardiebacker directly on this floor or must I absolutely have some 3/8" ply between the two?

I am aware of the Shluter-Ditra membrane but would rather not go that route unless someone has an incredibly persuasive reason why I should go that way.


I assume you're talking about (post #215911, reply #1 of 2)

I assume you're talking about ceramic tile.

The main question is flex -- is the subfloor stiff enough that the tile won't crack or be worked loose as people walk across it?  This depends on both the thickness of the lumber and the layout of the framing.  And how the boards are joined -- T&G makes for a stiffer floor.  (2x subfloor, if you really have it, might be stiff enough.)

Note that the size of the tile pieces is a factor -- larger tile needs a stiffer subfloor.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

The 2 X 6 floor is the full 2 (post #215911, reply #2 of 2)

The 2 X 6 floor is the full 2 inches thick-toe-nailed and face-nailed with 16d, over 4 X 12 spruce beams, variously spaced but either 24 or 36 on center. I don't hear any creaking but I'm sure there's a more precise way to be sure of flex.

I'm not sure about tile type but I have had my heart set on 12" travertine stone from HD.