Kitchen Sub Floor - tear up?

[tev9999]

I'm completly gutting and replacing my kitchen. I want to switch from vinyl to ceramic. Currently my floor consists of (from the joists up)...

1X6 boards diagional to the joists 3/4 plywood 1/8 lauan linoleum self stick tile

I get a little squeaking but nothing too bad, so it is in pretty good shape.

I know the lauan up should come out. Since I will have the entire floor clear, is it best to pull up the 3/4" plywood too and replace everything with cement board? Put 1/4" cement backer board over the existing plywood?

I also want to extend the tile into the living room 3-4' (around the counter that will be open to the living room), so I want it to remain level. The living is currently carpet over hardwood over the 1X6 boards. I will be replacing the carpet too.

Thanks for any advice.

[n_o_s_p_a__m]

I just did a small bathroom that was linoleum over luan. I removed both, exposing the 3/4" osb subfloor. I smoothed a thin layer of mortar over the subfloor, then screwed 1/4" hardibacker over the wet mortar. Then, I did as the Hardibacker company recommends, which is to finish the joints between the boards with thinset and fiberglass tape. Then, more thinset to adhere the tile to the hardibacker. One additional thing you can do for wet areas is to add a layer of plastic over the subfloor for additional moisture protection. Can I recommend a great finishing touch?: Get the metal threshold edging into which the edge of the tile that will be facing the now-carpeted area will fit (this goes in either before or after the hardibacker (depending on height). This will give a great look, and protect both the tile and the other area. Consider also the height of all the materials (backer-board, mortar, tile, etc) when designing.

Hope this helps.

-KJ

[Bill]

The key to a long lasting tile floor is preventing floor deflection. You say there is "a little squeeking". The floor must be rock solid for tile. The standard calculation is L/360 for the length of the span. Ex:

120"/360 = only a .33" deflection allowd over 10'.

Homeowner installation:

First, make sure your joists are 16" on center and solid. Some homes (especially remodels) use a post and beam construction which is unsutable for tile unless you get under the house and beef it up (as I had to). Post and beam are 4"x4" beams every 4' resting on posts that are placed every 4'. I had this problem in my bathroom. Fine for vinyl/carpet - bad for tile.

Next: I would as a minimum strip it down to the 3/4" plywood then add another layer of 1/2" plywood screwed in place. Even better would be to strip it down to the joists then attach 1 1/8" subfloor rated sheeting. The key is to have 1 1/8" of SOLID subfloor first. The other benefit of taking it down to the joists is the reduction in floor mismatch using only one wood substrate of 1 1/8. If you go this route there are circular saws available that can fit under your cabnet overhang for cutting the subfloor.

Finally: Attach 1/4" backerboard to the subfloor using the proper thinset morter and screws or nails rated for the installation (I'm not a fan of nails). Follow the instructions for the backerboard exactly. Note: Using the thicker 1/2" backerboard will not make up for a weak subfloor.

By prepping the floor this way it will insure many years of satisfaction.

-- Bill

[Bill]

The key to a long lasting tile floor is preventing floor deflection. You say there is "a little squeeking". The floor must be rock solid for tile. The standard calculation is L/360 for the length of the span. Ex:

120"/360 = only a .33" deflection allowed over 10'.

Homeowner installation:

First, make sure your joists are 16" on center and solid. Some homes (especially remodels) use a post and beam construction which is unsutable for tile unless you get under the house and beef it up (as I had to). Post and beam are 4"x4" beams every 4' resting on posts that are placed every 4'. I had this problem in my bathroom. Fine for vinyl/carpet - bad for tile.

Next: I would as a minimum strip it down to the 3/4" plywood then add another layer of 1/2" plywood screwed in place. Even better would be to strip it down to the joists then attach 1 1/8" subfloor rated sheeting. The key is to have 1 1/8" of SOLID subfloor first. The other benefit of taking it down to the joists is the reduction in floor mismatch using only one wood substrate of 1 1/8. If you go this route there are circular saws available that can fit under your cabnet overhang for cutting the subfloor.

Finally: Attach 1/4" backerboard to the subfloor using the proper thinset morter and screws or nails rated for the installation (I'm not a fan of nails). Follow the instructions for the backerboard exactly. Note: Using the thicker 1/2" backerboard will not make up for a weak subfloor.

By prepping the floor this way it will insure many years of satisfaction.

-- Bill

[Wayne Whitney]

The OP specified the existing construction is 1x6 diagonal plank subfloor with 3/4" plywood on top. That's not sufficient?

Cheers, Wayne

[calhoun]

Do you need to have the new floors finished height the same as the old? If not your existing subfloor (1 1/2") is fine. Screw it down real good than screw and thinset 1/4" cement board on it. That, with the tile, will leave your floor about 1/2" higher than the existing.

[Bill]

Yes. I neglected to include the 1x6 planks. Perhaps just the 3/4" over them would be fine. My one concern though is those planks are usually pretty flimsy and have knot holes in them. I guess when the OP strips the floor down to the 3/4" he'll see whether the floor feels solid.

I tend to do things a little overkill as I don't want to deal with it again. It's really not much harder to replace the floor down to the joists than to add additional layers. Me, I'd use new 1 1/8" and be done with it.

I recommed the excellent book, "Setting Tile" by Michael Byrne who goes into great detail on all the steps. Best book ever on it.

-- Bill

[Sacramento Dave]

Strip it down to 3/4 ply , You could probably run long screws ( grabber type) threw the ply and 1X6 into joist, can't hurt. You could even run some shorter screws threw the ply into the 1X6. Then use a 3/8" trowel for a thinnest bed before installing 1/4" backer board . Work one piece at a time, I used 1/4" roofing nails not screws. Everybody has to screw everything down half the time the backer board blows out or the head doesn't set. The thinset is going to glue it to the ply that's your holding power.I also used that mesh type tape on the joints when I install the tile. That's how a tile setter told me to do it .

[tev9999]

Thanks for the advice so far.

So looks like I should strip the kitchen down to the 3/4 inch ply, make sure it is screwed down tight, and add 1/4 cement backer board. On the part I am extending into the living room I would cut out the hardwood floor, add 3/4" ply to bring it up to the level of the kitchen, and the

1/4 backerboard. I'll make sure it is all done before cabinets go in so everything is nice and level.

Up to the tile would be medium-pile carpet over the existing hardwood (over the 1X6s). Right now the carpet is a little higher than the tile, so I think I should be good since the backerboard and thicker tile should bring them about even.

[tev9999]

My floor fun continues...

Just tore up the top two layers of vinyl and the 1/8" luann. What I thought was the 3/4 plywood over 1X6s actually has a layer of linolium (that looks just like plywood) over the 3/4 inch. There are now so many different heights and a sticky mess if I try to remove the fake wood, I think I'm going to take it back to the 1X6s and add new plywood. Does this sound like a good plan?

3/4" exterior plywood over 1X6s, screwed and glued Additional 3/4" plywood under cabinet footprint

--After cabinets are in.

1/4" Hardibacker board, screwed over thinset Ceramic tile.

[Keith Williams]

It's a lot of work. I just put down 5/8" TnG bamboo flooring. At the last minute I decided the foyer tile had to go. What a PITA chipping that up. The thinset didn't want to come off the 3/4" ply, so I cut it out and replaced a couple of sheets of it.

I don't think you have enough floor, particularly with 1x6s. I'm told[*] 5/4" flooring material is needed under tile. I've used

1/2" Hardibacker over 3/4" subfloor (w/thinset and screwed). The backer plus tile will be close to the 3/4" extra you have under the cabinets. [*] I'm just a weekend warrior too.

[tev9999]

More thoughts on this. What is the probability that the linolium I discovered contains asbestos? If it is the original floor, it would be from around 1956. It is a fake woodgrain pattern, fully secured with a black mastic. Seems very thin - thinner than the cheap vinyl tiles today. It is in pretty good shape - no adhesion issues I can see. It had about a million 1/8 X 1" staples through it from the top layer of plywood I removed, but I pulled all of them.

Can I put hardibacker over this without a problem if the underlying plywood/planks are secure to the joists?

[tev9999]

Keith,

Actually I was planning on new 3/4 under everything, then an additional

3/4 under the cabinets to bring them to the level of the finished tile floor so I don't have issues with moving the dishwasher in/out, etc. So under the tile it would be 1" plank, then 3/4 ply, then 1/4 hardibacker for a total of about 2". Now thinking of leaving the linolium in case it is an asbestos issue.

[Keith Williams]

Ah, I misunderstood incorrectly (was wondering why you were going to raise the cabinets ;-). You should be more than fine with 2". Yes, be careful with the dishwasher. I was pretty careful when measuring things when I raised my floor the 1/2" or so. The new DW

*just* cleared with the wheels on (they come off if another 1/8" is needed).

I think I would too, as long as you have that inch of material above it. I took up vinyl flooring in the laundry, bathroom for tile and in the kitchen/diningroom/hall for the bamboo. Pulling it up is a pain in the easy parts. The only thing I'd worry about if I didn't pull it upwould be any sliding between the linolium and ply. I'm not sure how it would (or if it need) be glued down.