# laying tile to straight to plywood subfloor..



## JWilliams

my brother and I recently bought a house. in his bedroom he wants to lay tile. he tends to think he can lay tile directly to the plywood subfloor. is it possible to do without installing backerboard? any info besides the facts that "you aren't suppose to do it that way" would be very helpful.


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## duburban

Not a tile expert but I would really look at framing and deflection first. If it's a stout frame not in a clients house.... But ultimately there is zero movement isolation so it's toast if anything moves. 

What's the roomsize? If you don't like backerboard or any of the other tile wonder products, use another sheet of 1/2 ply screwed between joists.


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## JWilliams

the room is about 15'x15' the room was an addition and the subfloor seems fairly level. and screwed down really well.


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## astor

As duburban says, deflection should be considered first, then you can look at Whisper Mat or similar such as Dal CIM 500 crack isolation membranes as well, more economical and easier to install.Will not effect height.


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## ohiohomedoctor

Just do it. Use liquid nails instead of thinset. :laughing:


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## clancrawford55

ohiohomedoctor said:


> Just do it. Use liquid nails instead of thinset. :laughing:


If you use silicone it acts as an isolation membrane.


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## ohiohomedoctor

clancrawford55 said:


> If you use silicone it acts as an isolation membrane.


Not a bad idea. Most likely would provide a more cushioned softer step as well. :thumbsup:


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## Warren

Tile in his bedroom? Why?


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## JWilliams

he thinks it will be easier to clean than carpet. and hes paying for it so he wants what he wants.


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## angus242

JWilliams said:


> my brother and I recently bought a house. in his bedroom he wants to lay tile. he tends to think he can lay tile directly to the plywood subfloor. is it possible to do without installing backerboard? any info besides the facts that "you aren't suppose to do it that way" would be very helpful.


Well I know I've been told to stick the TCNA up my ass earlier today...but...Tile always needs an underlayment. Even if you lay over plywood, you still need a plywood underlayment. TCNA suggests a minimum of 1 1/8" of ply before installing tile directly over. 

So what your brother tends to think is correct but not in the state that his bedroom is today. I know the next issue will be expense....Is it less expensive to do it properly the first time or to repeatedly repair grout issues (cracking) over the long run?

Thinset, 1/4 CBU, screws or nails, taped seams, tile.

Thinset, Ditra, tile.

Mapei Mapelastic CI, tile.

Thinset (or EXT is Noble), sheet membrane, tile. 

Those are multiple options AS LONG AS there's a minimum deflection of L/360.


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## ohiohomedoctor

angus242 said:


> Well I know I've been told to stick the TCNA up my ass earlier today...but...Tile always needs an underlayment. Even if you lay over plywood, you still need a plywood underlayment. TCNA suggests a minimum of 1 1/8" of ply before installing tile directly over.
> 
> So what your brother tends to think is correct but not in the state that his bedroom is today. I know the next issue will be expense....Is it less expensive to do it properly the first time or to repeatedly repair grout issues (cracking) over the long run?
> 
> Thinset, 1/4 CBU, screws or nails, taped seams, tile.
> 
> Thinset, Ditra, tile.
> 
> Mapei Mapelastic CI, tile.
> 
> Thinset (or EXT is Noble), sheet membrane, tile.
> 
> Those are multiple options AS LONG AS there's a minimum deflection of L/360.


Thats a big book to,,, well you know. How ya feeling after that? :laughing: :laughing:


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## angus242

ohiohomedoctor said:


> Thats a big book to,,, well you know. How ya feeling after that? :laughing: :laughing:


Luckily, I grabbed the 2009 version!


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## Inner10

Around here the inspector looks for 1-1/4" of wood minimum for tile. 

Most houses use 3/4" OSB and 1/2" spruce ply. Tile is applied directly to the ply.

Although all the homes in the 600K+ price bracket seem to have ditra.


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## ohiohomedoctor

angus242 said:


> Luckily, I grabbed the 2009 version!


Or at least thats what came out. Might want to check for the rest...


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## tgeb

I'm in the excavation business and know better than to tile over plywood.

Do it correctly.


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## JWilliams

thanks for the comments but other than the tile needs an underlayment or youre not suppose to do that. what is the actually reason why? not trying to cut corners just want to know the actually reasons


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## ohiohomedoctor

JWilliams said:


> thanks for the comments but other than the tile needs an underlayment or youre not suppose to do that. what is the actually reason why? not trying to cut corners just want to know the actually reasons


You already got the answer. Deflection, adherence.


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## angus242

Wood expanding/contracting. Deflection of joists. Deflection of plywood.


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## ohiohomedoctor

angus242 said:


> Wood expanding/contracting. Deflection of joists. Deflection of plywood.


Ha, I beat you too it. 1rst time for everything.


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## angus242

I typed more :jester:


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## Mike-

Inner10 said:


> Lets pipe down we don't want to give away the ancient Canadian secret.


Hahaha. Sssshhhhhhh it's a secret. 

What were all the tile setters using back 30 years ago? Just curious. Was Ditra and noble and products like this available then? What were there installation methods. I have walked through around 30 homes in this area when I decided on my place and it seems I could not find any failures really besides sloppy grout jobs and let me tell you, they were in no way fashionable so I could see the install was at least 15 plus years.


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## Mike-

Floormasta78 said:


> By the way I did this today.. Alone..oh yea !!


If there were voice note options on Ct I would send you one with a crowd of ppl clapping and cheering!


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## astor

Inner10 said:


> Lets pipe down we don't want to give away the ancient Canadian secret.


Don't let anyone know, a lot of people may loose their jobs:
TCNA manual may become just one page.
Thin set companies start making just one type thinset, why bother.
All underlayment co;s close,Schluter, Noble etc.
No CT


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## astor

Mike- said:


> Hahaha. Sssshhhhhhh it's a secret.
> 
> What were all the tile setters using back 30 years ago? Just curious. Was Ditra and noble and products like this available then? What were there installation methods. I have walked through around 30 homes in this area when I decided on my place and it seems I could not find any failures really besides sloppy grout jobs and let me tell you, they were in no way fashionable so I could see the install was at least 15 plus years.


1989-1990 I did over 35 homes at Richmond Hill for a builder with Ditra.That is 21 years ago.All galvanized framed homes. You never seen at that time does not mean they were not available:whistling


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## astor

IMHO spec home builders use cheapest materials and labor as possible,liabilities on him-limited with one year in Canada-, But when you do custom stone or tile job where the materials are pricey,there is no cutting corners,risks are high, In US,professional setter is liable and under risk as lawsuits are more common.
Also from business point,why not make more money, by upselling quality materials and more quality labor?


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## Mike-

astor said:


> IMHO spec home builders use cheapest materials and labor as possible,liabilities on him-limited with one year in Canada-, But when you do custom stone or tile job where the materials are pricey,there is no cutting corners,risks are high, In US,professional setter is liable and under risk as lawsuits are more common.
> Also from business point,why not make more money, by upselling quality materials and more quality labor?


I absolutely agree with you on that notion. I agree it is far superior to use product like Ditra,NS hyrdoban and so on. And yes they absolutely work. Myself included, I give an option to the homeowner of better or best for installation type methods but I do carry a minimum in which I will provide, not only for years of dependable enjoyment,but to know that it is to code and backed by warrenty(whatever warrenty means now adays).


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## Mike-

I guess when the budget gets tight, builders gotta pinch in certain areas.


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## Floormasta78

Thanks mike.. This is the way tile was done many years ago


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## angus242

Floormasta78 said:


> Any more questions?.


Yeah. Why is it always sideways? :lol:


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## TNTRenovate

angus242 said:


> Yeah. Why is it always sideways? :lol:


Because that's how they used to do it?


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## angus242

Mike- said:


> Hahaha. Sssshhhhhhh it's a secret.
> 
> What were all the tile setters using back 30 years ago? Just curious. Was Ditra and noble and products like this available then? What were there installation methods. I have walked through around 30 homes in this area when I decided on my place and it seems I could not find any failures really besides sloppy grout jobs and let me tell you, they were in no way fashionable so I could see the install was at least 15 plus years.


So you're condoning this type of install? Do you think the fast-track methods of today stand up to how homes were built 30 years ago? Are you suggesting that the methods recommended by the TCNA today are not worthy? Please elaborate.


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## Big Shoe

I've had to rip out tile thinseted directly to particle board 

Thank God they nailed the particle board down because that was the only way to remove the tile. 

2x12 joist,1/2'' ply, 1/2'' particle board,thinset and tile. 20+yrs. Not a crack, rock solid.

Just say'n :whistling


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## Tech Dawg

Mike- said:


> Most of the new home builds here in the Vancouver area are 3/8 ply subfloor, thinset,tile. That's it. And no issues.


How is this possible? Are the joists on an 8" spread?? I've torn down to 1/2" subfloors where the ply sinks an inch when you step between the joists


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## Floormasta78

I have a samsung galaxy 2 .. and when I upload from the CT app, my pictures turn.. ??


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## ohiohomedoctor

Floormasta78 said:


> I have a samsung galaxy 2 .. and when I upload from the CT app, my pictures turn.. ??


Trying laying on your side while you take the pictures...


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## Floormasta78

Real funny Doc.. Lol !


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## The Coastal Craftsman

Inner10 said:


> Thinset right to plywood is standard practice here...I don't know what the secret is but I don't see tiles cracking or falling off.


There is no secret. It's one of them myths that it won't hold if it's not done with isolation membrane. I have seen good and bad installs with membranes and without. I use a membrane if a customer wants it and don't tell them it's not worth it as it's more money in my pocket but I have never ever had one issue in all the years I have done tilling when installed on plywood. I even it like that in my own house. A nice thin coat of pva makes thinset stick to plywood like you wouldn't believe. the tile guy who used to do our bathrooms back in UK was dead against any membranes of any kind. He was old school for sure but was one of the best tile installers I ever come across to this day and he said he had never had one call back in all is years doing it where laying it on plywood didn't workout. Get this though. The one time we convinced him to tile a shower with a membrane the dam thing leaked lol


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## angus242

BCConstruction said:


> There is no secret. It's one of them myths that it won't hold if it's not done with isolation membrane. I have seen good and bad installs with membranes and without. I use a membrane if a customer wants it and don't tell them it's not worth it as it's more money in my pocket but I have never ever had one issue in all the years I have done tilling when installed on plywood. I even it like that in my own house. A nice thin coat of pva makes thinset stick to plywood like you wouldn't believe. the tile guy who used to do our bathrooms back in UK was dead against any membranes of any kind. He was old school for sure but was one of the best tile installers I ever come across to this day and he said he had never had one call back in all is years doing it where laying it on plywood didn't workout. Get this though. The one time we convinced him to tile a shower with a membrane the dam thing leaked lol


I don't know where to even start....


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## Mike-

angus242 said:


> So you're condoning this type of install? Do you think the fast-track methods of today stand up to how homes were built 30 years ago? Are you suggesting that the methods recommended by the TCNA today are not worthy? Please elaborate.


Did you read my above comment. It happens everyday, but I would not just do it.


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## angus242

Inner10 said:


> Thinset right to plywood is standard practice here...I don't know what the secret is but I don't see tiles cracking or falling off.


Like I said, it's an acceptable practice if done properly.



Mike- said:


> Most of the new home builds here in the Vancouver area are 3/8 ply subfloor, thinset,tile. That's it. And no issues.


3/8" ply SUBFLOOR? :no:

3/8" ply underlayment? Perhaps. Still incorrect method.




You can tile directly over a lot of (incorrect) materials with a lot of (incorrect) adhesives and they might work. Tiling is not a black and white trade. The reasons I choose to follow the recommendations of the TCNA (that book up my ass still hurts) is because they have tested and tested and tested method upon method upon method and published their best results. Call me a wacko shifty but I want to use the method that's going to give me the best chances at a successful long term install. 

Why in hell would I purposefully choose a method that has been known to fail? I suppose if I didn't care about much more than putting money in my pocket is one reason. Because I don't care about longevity of my installs would be another.

Wood is perhaps the most unstable substrate in an entire house. It's affected by heat/cold and moisture more than any other substrate I know off. Basically, wood moves...a lot. Why would you want to install a material like tile directly over it? 

Just because you can do something doesn't mean you should.


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## Mike-

angus242 said:


> Like I said, it's an acceptable practice if done properly.
> 
> 3/8" ply SUBFLOOR? :no:
> 
> 3/8" ply underlayment? Perhaps. Still incorrect method.
> 
> You can tile directly over a lot of (incorrect) materials with a lot of (incorrect) adhesives and they might work. Tiling is not a black and white trade. The reasons I choose to follow the recommendations of the TCNA (that book up my ass still hurts) is because they have tested and tested and tested method upon method upon method and published their best results. Call me a wacko shifty but I want to use the method that's going to give me the best chances at a successful long term install.
> 
> Why in hell would I purposefully choose a method that has been known to fail? I suppose if I didn't care about much more than putting money in my pocket is one reason. Because I don't care about longevity of my installs would be another.
> 
> Wood is perhaps the most unstable substrate in an entire house. It's affected by heat/cold and moisture more than any other substrate I know off. Basically, wood moves...a lot. Why would you want to install a material like tile directly over it?
> 
> Just because you can do something doesn't mean you should.


So would you say deflection would be enemy #1 in an install of this nature?


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## angus242

Deflection is _always_ an enemy. Not only is it the deflection of the joists but also the deflection of the subfloor _between_ the joists. Expansion joints are also important. Whether it's the gaps in the T&G or the perimeter of a room (2nd layer of ply to bottom plate). 

The floor is going to move, convex/concave and expand/contract at a different rate than tile will. You need to account for that movement. If you don't, that brings a much higher risk of failure to the equation.


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## Mike-

angus242 said:


> Deflection is always an enemy. Not only is it the deflection of the joists but also the deflection of the subfloor between the joists. Expansion joints are also important. Whether it's the gaps in the T&G or the perimeter of a room (2nd layer of ply to bottom plate).
> 
> The floor is going to move, convex/concave and expand/contract at a different rate than tile will. You need to account for that movement. If you don't, that brings a much higher risk of failure to the equation.


How are the rating of deflection derived. How would I know if my install would meet the manufacturers deflection rating? 

Trying to learn. Thanks for the help.


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## angus242

Basically, the minimal deflection allowed on a subfloor system is L/360 for installing ceramic-based tile. The deflection changes to L/720 for stone installations. 

It's a bit complex but you need the following info to determine deflection:
Joist unsupported length
Joist size
Joist spacing
Joist material (wood species)

Kind of rule of thumb is 2x10 with 16"OC and douglas fir the longest span is about 14'...give or take. Smaller joists, larger centering or different wood species will change that. 

If you ever have a question about deflection, you can post the info here and a few of us can give you a close estimate on the ratio. I use a combination of a few charts I've found over the years. There is another forum that has a calculator. They are a competing forum so I won't mention them but you might be able to figure that out on your own. Either way, no big deal.

Now if you have I-joists or engineered trusses, you need to call the manufacturer. They are usually stamped with manufacturer info and anytime I've done this, the tech departments have been very helpful in giving me the info needed.


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## The Coastal Craftsman

angus242 said:


> I don't know where to even start....


Angus you make it sound like the only way is your way! My mum laid tile onto 5/8th tounge and groove pine with a wooden cooking spoon when I was on vacation for 2 weeks and to this day never thought it would have stayed down. But 10 years on the tiles are still down! Not only did she use a spoon I later found out she had used grout as the adhesive :laughing: every time I go back home and see that tile I always hope it's come up. I have tore out over 100 bathrooms in the last 8-9 years and I can count on one hand the ones that come up with little to no effort. At least half of the ones that did stay down well were on thin sub floors and had awful deflection yet we had to use air chippers or complettly tear out the subfloor to get the tiles up.


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## Tech Dawg

BCConstruction said:


> Angus you make it sound like the only way is your way! My mum laid tile onto 5/8th tounge and groove pine with a wooden cooking spoon when I was on vacation for 2 weeks and to this day never thought it would have stayed down. But 10 years on the tiles are still down! Not only did she use a spoon I later found out she had used grout as the adhesive :laughing: every time I go back home and see that tile I always hope it's come up. I have tore out over 100 bathrooms in the last 8-9 years and I can count on one hand the ones that come up with little to no effort. At least half of the ones that did stay down well were on thin sub floors and had awful deflection yet we had to use air chippers or complettly tear out the subfloor to get the tiles up.


I don't think Angus is bashing this method... Bill Vincent knows a lot about this process so maybe he'll jump in.
There's no room for error w/ tile over ply. You need 2 layers of BC and the top joints have to be siliconed. Next to a mud set floor it takes a lot longer than what you think and you spend quite a bit more using a top quality thinset like 254 platinum or 272 with admix which is most recomended...


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## angus242

BCConstruction said:


> Angus you make it sound like the only way is your way!


I don't think you read quite everything I wrote then.

I believe I suggested *4* different methods in the beginning of this thread.

I also said tiling over plywood _is_ an accepted method.

I also said there are _many ways_ to tile and the more you stray off recommended methods, the greater the chance of failure. 

Never did I say all non-recommended methods will fail. 

I take my trade seriously and hope that the info given here will help others be successful. Since there are so many variables or would and could, the best way to spread good advice is to stick to the proven. You've been here long enough to see how many tile noobs come strolling through. If we suggested grout as an adhesive spread with a wooden spoon to all of them, how many would end up successful? 

My point is I fight for the proven. If someone wants to go rogue, that's on them. 

And a tile failure doesn't always equate to tile coming up easily. My last demo job took a demo hammer to remove the tiles that wer installed correctly in every way....except one. They used DensShield as the underlayment but didn't tape the seams. Guess where the grout was cracking.....


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## CO762

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## Mike-

angus242 said:


> I don't think you read quite everything I wrote then.
> 
> I believe I suggested 4 different methods in the beginning of this thread.
> 
> I also said tiling over plywood is an accepted method.
> 
> I also said there are many ways to tile and the more you stray off recommended methods, the greater the chance of failure.
> 
> Never did I say all non-recommended methods will fail.
> 
> I take my trade seriously and hope that the info given here will help others be successful. Since there are so many variables or would and could, the best way to spread good advice is to stick to the proven. You've been here long enough to see how many tile noobs come strolling through. If we suggested grout as an adhesive spread with a wooden spoon to all of them, how many would end up successful?
> 
> My point is I fight for the proven. If someone wants to go rogue, that's on them.
> 
> And a tile failure doesn't always equate to tile coming up easily. My last demo job took a demo hammer to remove the tiles that wer installed correctly in every way....except one. They used DensShield as the underlayment but didn't tape the seams. Guess where the grout was cracking.....


Thanks for the help as always. You tile guys have been a great help and are helping me to learn and install tile the professional way.


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## Tech Dawg

Mike- said:


> Thanks for the help as always. You tile guys have been a great help and are helping me to learn and install tile the professional way.


Jus don't us a wooden salad fork to notch your thinset :laughing:


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## CO762

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## The Coastal Craftsman

Tech Dawg said:


> Jus don't us a wooden salad fork to notch your thinset :laughing:


Stop giving incorrect advice as it's gonna go bad if he don't use the correct tools. It was not a fork it was a spoon like this :thumbsup:













sorry Angus I just went through the posts quickly and didn't see half your posts. But I agree that membranes do help in certain situations.


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## angus242

BCConstruction said:


> I just went through the posts quickly and didn't see half your posts.


Yeah, I post a lot :blush:


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## CO762

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## The Coastal Craftsman

CO762 said:


> I've heard of that. I've also heard of other things.
> 
> 
> Well then, that method has a 50% success rate. heck, who can argue with that? Charge half rate on the front end and if it fails, one can recoupt their money if they charge double rate for a redo.
> 
> Then it'll be 50% failure rate of the original 50%. One more time after this go round and on the next redo, you'll be approaching the 90% success rate :thumbsup:


I said at least half the ones that did stay down well had bad subfloors. The other half were on good subfloors. I didn't say half failed and half didn't.


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## CO762

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## astor

CO762 said:


> Like Angus said, there's wiggle room in any trade relative to procedures and materials. The better/more experience one gets the more options, yet physics be physics and probabilities be probabilities. They don't favor anyone. The reason there are 'approved' methods/materials and their exceptions are to try and exclude any exceptions. Example, use a membrane over plywood and if the plywood fails, the membrane will compensate and make the install still a success. Set over plywood and if the plywood fails, the install fails. Physics and Probabilities....and what people are willing to wager.


Exactly correct,,why take risks-even it is small-when you have a knowledge and skills to do it failure free..or with minimal risk as possible.
You may lay 1000 sq.ft of tile over ply, may look and stay good until a joist moves and effects say 10 tiles, you go fix it and 6 months later again same thing, can you afford? If so go ahead...never mind your reputation or referrals you may not get ...


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## ohiohomedoctor

CO762 said:


> I've heard of that. I've also heard of other things.
> 
> Well then, that method has a 50% success rate. heck, who can argue with that? Charge half rate on the front end and if it fails, one can recoupt their money if they charge double rate for a redo.
> 
> Then it'll be 50% failure rate of the original 50%. One more time after this go round and on the next redo, you'll be approaching the 90% success rate :thumbsup:


I dont get it.


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## Tile King

I will never, ever, Ever! Lay tile (hard) on wood. Just my opinion. Don't trust the flex mortars, will not use lewon...(don't even spell it right). Only will use cement board, tar paper wire and screed, ditra, or even the worst I'll use is hardi. That's only my opinion. Sorry if you diagree, but I don't like punchlists! Good luck with that wood!


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## Tech Dawg

If anyone is setting tile on luan, they should be shot :laughing:
The moisture from the thinset would delaminate it in a matter of minutes...


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## ohiohomedoctor

Tech Dawg said:


> If anyone is setting tile on luan, they should be shot :laughing:
> The moisture from the thinset would delaminate it in a matter of minutes...


I say let them do it. Then someone qualified will get the rip out and replace job.....


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## Tile King

Yes I have been ripping old tile out in some customers homes and underneath was luan! What a joke the builders out here are! Unbelievable they are allowed to even exist and continue building!


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## CO762

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## CO762

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