I am about to take on a flooring project and I have never done this before. The previous owner did a DIY flooring job and it's horrible. Cracked tiles and chipping grout everywhere. So as I have been told....easy to pull up.

The problem I face is the sub flooring or lack of any solid surface...hence the cracked tiles.

The original tile was laid straight on to the original 1968/1969 builder sub floor. The best way to describe this floor is 1" thick / 2" wide diagonal wood with 1/4" gaps. So if I pull and ceiling tile downstairs I get and face full of mortar that has crept through the gaps. Like I said.....horrible.

So my question is do I lay 3/4" tongue and groove sub flooring followed by 1/4" back board? 3/4" sheets screwed to joists? or just every 6 inches in to my 1x2 planks?

If I do anything asked above I will have a 1 to 1-1/2" threshold difference from the old hardwood to new floor. Kind of a toe stubbing nightmare lurking.

It doesn't have a noticeable bounce. The area is a kitchen so maybe the cabinetry is helping?

  • 1
    Does the floor have a bounce or flex to it when you walk on it? Just backer board might be enough if it's relatively solid. (you'll have to remove the tiles to really tell if you haven't already)
    – JPhi1618
    Commented Aug 21, 2019 at 21:04
  • Have you considered removing the original subfloor? 3/4" OSB under 1/2" CDX plywood or cement board would be great. You'd end up at least a half inch lower than your current plan.
    – isherwood
    Commented Aug 22, 2019 at 2:43
  • From what I read there is no sub floor just the planks that are gapped that’s why I suggested “decking” the last house I built 1” was available but that was 17 years ago since then mostly commercial electrical work I may be out of touch but if decking is not available I could make it in a few minutes for each sheet with bits I have. I really think this is needed since the existing decking is gapped ,,, at least for a quality tile install. Love doing tile work but make more as an electrician, still help a contractor buddy on the side but at my age and after 18 knee surgery’s only a few lately
    – Ed Beal
    Commented Aug 22, 2019 at 3:13

1 Answer 1


Wow sure that floor would bounce. Rip up the old tile and use plywood decking. I can’t remember if you can get 3/4 in t&g but know you can get 1”. Since the strips are not t&g I would want to go thicker if possible. If not use a lot of construction adhesive and screw the plywood down.

Next step is your backer board. (I usually put thinset or mastic under my backer and screw it down.) The more solid your base is the better chance of a long life you have (for your tile). After that you are ready to tile.

The threshold will be angled but that is the only way to do it right. I have dropped a finishing hammer from the ceiling on a 4” tile. I was sure I bullseyed the tile but it was ok. I got lucky but part of that luck came from the base the tile was on. I have repaired tile that a heavy cooking spoon fell from the counter and cracked the tile--it did not have a good base.

Don’t skimp, you should not have an observable flex in the flooring if you want it to last.

  • 1" what, Ed? 3/4" plywood or OSB are standard. 1" is a special order at most yards (and probably expensive as heck). Otherwise, I agree.
    – isherwood
    Commented Aug 22, 2019 at 2:41
  • I have purchased 1” decking or plywood that is tongue and grove, it was stock but that was a few years back most of the decking I have purchased is 1-1/2 then some under layment on top if tile cement or backer board, if vinyl mdf or beaver board have done this on multiple homes and for friends and clients.
    – Ed Beal
    Commented Aug 22, 2019 at 2:58

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