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1/4 pine plywood , self-leveling compound, Ditra

22K views 58 replies 8 participants last post by  RRBartlett52 
#1 ·
Hi everyone,

i am planning to put tiles on my second stores kitchen's floor.
i have pulled out the previous vinyl floor and other wood board.
As you can see from the pictures i have uploaded, the kitchen's floor are left with slat wood(i think) and some 3/4 plywood around the exit door area.
Floor Property Flooring Tile Hardwood


Floor Flooring Property Wall Tile


Floor Flooring Property Wood Hardwood


Floor Flooring Wood Hardwood Wood flooring


Yellow Amber Wood Floor Hardwood


Floor Flooring Property Wood Hardwood


should i perform the following steps to tile my floor?
1) screw down 1/4 pine plywood on the floor
2) use cement mud the gaps between the plywood
3) use latex primer to prime the plywood
4) level the floor with self-leveling compound
5) install Dita underlayment
6) then install the tiles....

any help would be nice
Thank you
Phil
 
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#2 ·
Where on earth are you getting all of that information?

1) screw down 1/4 pine plywood on the floor
NEVER use 1/4" plywood in a tile installation, 3/8" is the absolute minimum. The correct plywood would be "Exterior Grade Exposure 1 Underlayment".
2) use cement mud the gaps between the plywood
NEVER do that either. Those gaps need to be able to expand and contract. Use caulk.
3) use latex primer to prime the plywood
You use the primer recommended by the Self Leveler manufacturer.
4) level the floor with self-leveling compound
5) install Dita underlayment
WHY do you want to use DITRA AND Self Leveler?
6) then install the tiles....
 
#4 ·
Hi Bud
Thank you for your info
So, are you saying my tile's underlayment would be fine if i level the whole floor with self-leveled compound? and i can skip the Ditra step?

What about contraction and expansion? would the subfloor's contraction and expansion affect the layer of the self-leveled compound (would it crack?), and therefor affect the tile?
 
#7 ·
somuchtolearn said:
Hi Bud Thank you for your info So, are you saying my tile's underlayment would be fine if i level the whole floor with self-leveled compound? and i can skip the Ditra step? What about contraction and expansion? would the subfloor's contraction and expansion affect the layer of the self-leveled compound (would it crack?), and therefor affect the tile?
I am not convinced that your subfloor is plywood.
If it's plank flooring self leveling the entire floor won't work and or won't last.

You need Ditra or Cement board for tiles to bond and hold.

Steps I would recommend:
Tell use what exactly is your subfloor made up of?
Can you find out what is supporting subfloor? Like joists and span? How about the thickness of this so called subfloor?
 
#8 ·
Hi Jet
Thank you for your time checking my problem.
I have uploaded new pictures of the floor.
Leaf Macro photography


Wood Floor Flooring Tile


Wood Floor Wall Plywood Hardwood


Wood Hardwood Floor Room Plywood


Wood Floor Mineral Rock


Wall Wood Floor Hardwood Wood stain


I have replaced the old plywood(It laid directly on the joist) with the new 3/4'' plywood near the exit area. From that, i know the joists are 19 oc. The hardwood locking floors are 3/4" and are laying perpendicular to the joist. There seem to be nothing under the hardwood locking floor .( i could be wrong.)

Please advice me what i should do next....

Thank you
 
#9 ·
somuchtolearn said:
Hi Jet Thank you for your time checking my problem. I have uploaded new pictures of the floor. I have replaced the old plywood(It laid directly on the joist) with the new 3/4'' plywood near the exit area. From that, i know the joists are 19 oc. The hardwood locking floors are 3/4" and are laying perpendicular to the joist. There seem to be nothing under the hardwood locking floor .( i could be wrong.) Please advice me what i should do next.... Thank you
Thanks for providing us more details on your floor.

You stated you took section up by door was the T&G in that area? If so you took that up and then the old plywood that was over joists right so it would be the same in the hole room.
At this point I still can not say go ahead and SLC over the T&G planks it can and will flex if it doesn't have enough support underneath therefore making SLC and grout to crack. You stated joists are 19oc so for example you need thicker plywood for wider joist span.

I would suggest next move is to find out why your floor is not completely flat.
You can take a string with 2 screws on each side of the room, tie the string to the screws tight about 1-1/2" off floor and run a cut piece of 2x4 along the string marking the difference as you go and repeat method for the other 2 sides of the room.
 
#10 ·
I've tiled a few floors directly onto the SLC. If done right, it creates a perfectly flat, sound surface for your tile. But you can't pour SLC onto dimensional lumber, you need exterior grade plywood between the tongue and groove boards to isolate from the natural expanding and contracting of the wood.

And my entire house is tongue and groove floor boards with no sub floors upstairs or downstairs. It's not all that uncommon.
 
#14 · (Edited)
Leave the T&G. Put plywood over top of it. Use the SLC over the plywood.

Do NOT put SLC on top of dimensional lumber. No matter how much you screw the wood down it will shift. Plywood does not shift because the alternating layers are at 90 degree angles and basically cancel each other out.

That said, any place that the T&G floor shifts, bounces or squeaks, you'll need to screw it down, shim it from under neath or otherwise stabilize it. Then use screws long enough to go through your plywood, through your T&G and then into the joists at least an inch.

You can put down a threshold that bridges the different floor heights. It's not a big deal.

Oh, and I am not the person to ask about using Ditra, I know absolutely nothing about it. Never used it, never considered using it, so never looked into it.
 
#15 ·
Well your going to have to go with ditra at this point as your floor will be high.
mnp13 stated it the best on how to do this with out taking up the T&G, I on the other hand would have taken that up if it was me but you should be fine.

When installing ditra over plywood you use a modified thinset, then unmodified for tile installation but make sure you read the little hand book the ditra membrane comes with.
 
#17 ·
mnp13 said:
He still needs to level the floor, so once the SLC is down, there will be a flat, stable surface to tile on. Why would a layer of ditra be necessary?
The ditra Is for the tile to bond and to be held down.
IMO ditra is best for bathrooms, wet rooms, showers ect, the floor will be too high to put CBU down unless the op takes T&G out.
Is it possible to tile on like a B/C sanded plywood with modified thinset yes, but defiantly not recommended in this forum.... Lol and certainly not with the uncertainty of T&G planks.
 
#22 ·
You can tile directly on SLC. It's made to tile on. I can't see a reason to add another layer just because. The tile will bond perfectly well to SLC - it's perfectly flat, hard and stable.

And I have never seen anyone say that tile should be put directly on plywood. Never a professional, never a book, never an article. Do people do it? Yes, all the time. One water leak, and the plywood swells, and your floor is destroyed. Which, incidentally, is exactly what happened in my friend's townhouse when her refrigerator's ice maker started leaking.
 
#21 ·
wkearney99 said:
Me too, I'd pull it up and put down 3/4" subfloor plywood. If that doesn't raise the level too high I'd use 1/4" cement backer, otherwise Ditra. Have you checked that your joist span is going to handle the type of tile you plan on putting down? Tile is going to be MUCH heavier than what was there before. Especially stone tile (ceramic, porcelain, stone, usually in that order by weight). Because even with the plywood if the joists won't handle the weight then they'll bend and flex, which will lead to cracking the tile floor laid above it.
The joists has been stated 19oc so 3/4" over joists would be pushing limits.... 16oc? Yes. 3/4" then 1/2" then 1/4" cbu is the best way IMO.
 
#23 ·
Some posters here are boldly posting without an understanding of the principles of the trade.

For example: Porcelain is a form of ceramic tile but still some insist on separating the two as if they were two.

For example: Installing tile on plywood is never recommended. If the technique doesn't appear in the TCNA Handbook for Installing ceramic Tile then the technique is not acceptable. I can tell you that technique does not appear anywhere in the handbook. The technique is also NOT sanctioned by the CTEF or any major contractors association.

For example: Natural stone tile installations requires two-layers of approved plywood. This from both the TCNA and the Marble Tile Institute of America.

The only people "destroying this thread" are those of you that choose not to follow the rules of the trade.
 
#24 ·
mnp13 said:
You can tile directly on SLC. It's made to tile on. I can't see a reason to add another layer just because. The tile will bond perfectly well to SLC - it's perfectly flat, hard and stable. And I have never seen anyone say that tile should be put directly on plywood. Never a professional, never a book, never an article. Do people do it? Yes, all the time. One water leak, and the plywood swells, and your floor is destroyed. Which, incidentally, is exactly what happened in my friend's townhouse when her refrigerator's ice maker started leaking.

Yes tiling over SLC works but it holds no structure unless you make it inches thick lol
I have never SLC on plywood more then a couple sqr feet.
I am not ashamed on saying I have tiled over plywood may of time with no issues to date. Your tile install is waterproof if done right. I'm not the only one who has done it although I don't anymore people I'm sure still do.
 
#26 ·
Bud Cline said:
Some posters here are boldly posting without an understanding of the principles of the trade. For example: Porcelain is a form of ceramic tile but still some insist on separating the two as if they were two. For example: Installing tile on plywood is never recommended. If the technique doesn't appear in the TCNA Handbook for Installing ceramic Tile then the technique is not acceptable. I can tell you that technique does not appear anywhere in the handbook. The technique is also NOT sanctioned by the CTEF or any major contractors association. For example: Natural stone tile installations requires two-layers of approved plywood. This from both the TCNA and the Marble Tile Institute of America. The only people "destroying this thread" are those of you that choose not to follow the rules of the trade.
I know what the handbook states and if I want to void it I can cause I know what I'm capable of tiling wise.
Anyway we all know that The user is not going to tile over plywood so this is mute point.
I just so happen to know everything there needs to know the deference between porcelain and ceramic tile, the water absorption ratio and PE rating... Ect.
I have worked with many tile setters, I know what works and what doesn't.
 
#28 ·
Thank you guys for all your good intended advice.
The tiles i will be using are 1/3'' thick 1' by 2' porcelain tile.
i read all your comments and did a bit of research on other website, i think i should...

1.put screws to the pine wood through the joists where i feel i the floor is "weak".

2. place 3/8 inch plywood (Exterior Grade Exposure 1 Underlayment) over the floor with screws. (screw only pass through plywood and pinewood with no penetration into joists.)

3. seal the gaps between the plywood with caulking.

4. prime the plywood with primer

5. level the plywood floor with SLC (as thin as possible)

6. install the ditra underlayment ( you know just incase the SLC does crack)

7. install the tiles.

Question: can i actually install Ditra over a floor surrounded by SLC? which mortar is suitable for this application?

Thank you
 
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