Ceramic Tile on plywood flooring

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  #1  
Old 07-05-12, 09:37 AM
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Ceramic Tile on plywood flooring

Looking for thoughts on this project
Ceramic tile 17x17 tiles
Floor - 2x10 joists - 16" o.c., span 15'
3/4" T&G sub-floor - glued and screwed
Our contractor states he uses 1/4" A-grade exterior plywood adder with offset seams - so 1" total sub-flooring when done
Thin set bed directly on that surface - no hardi-backer/durock board.

So much of what I read states 1-1/4" min. (which adds little to strength of floor).

Is this risky? My contractor or tells me he has been doing this for over 20 years and has had no problems. Should I be concerned?
 
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  #2  
Old 07-05-12, 09:52 AM
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Welcome to the forums.

This is not a standard installation, I would not do it.

The pros will be along shortly with more details for you.
 
  #3  
Old 07-05-12, 11:23 AM
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Not a tile pro but I know that several of the thinset manufacturers list exterior grade plywood as an acceptable substrate. I have read concerns about tile on plywood. I think the issue was that the bond strength of the thinset might be affected by the plywood removing moisture before the thinset was cured. According to the manufacturers polymer additives are mixed with the thinset to prevent that.

While I have not used thinset over plywood, I have used mastic (sometimes called pre mixed thinset) over plywood without a problem. It could be that your contractor is either using one of the thinsets where plywood is acceptable or he is using mastic.

I've never used 1/4" plywood as a substrate, I have always used 5/8" - 3/4". Is your 3/4" T&G subfloor plank or plywood?
 
  #4  
Old 07-05-12, 12:01 PM
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Plywood.
I would prefer he use 1/2" to get the 1-1/4" recommended total subfloor thickeness based on what I have read thus far. I am putting in 3/4" hardwood in adjacent area and would like to minimize transition change if possible, so the 1/4" adder would help in this regard, but that seems minor compared to potential tile problems down the road.
 
  #5  
Old 07-05-12, 12:20 PM
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I am told he uses a "A" Marine grade 1/4" plywood over 3/4" subfloor plywood and has been doing this for many years.
 
  #6  
Old 07-05-12, 12:25 PM
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It may work but is not the way I would do it.
 
  #7  
Old 07-05-12, 12:46 PM
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Mitch17 thanks for your input. It has me a bit nervous now.
So many people I know have recommended this contractor as meticulous, thorough and one of the best in our area...... Not sure what to think...
 
  #8  
Old 07-05-12, 12:50 PM
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See what he has to say - tell him his installation is not up to industry standards. Hopefully he can respond with something better than "I've been doing it this way for years and never had a problem."
 
  #9  
Old 07-05-12, 01:29 PM
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I will discuss with him, but at the end of the day I want it to be up to snuff or better, so I will require at least 1/2" adder. Thanks.
 
  #10  
Old 07-05-12, 01:57 PM
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1/4" plywood is not an acceptable underlayment for ceramic or porcelain tiles. It is ok for linoleum. He must use an isolation membrane such as concrete backer underlayment or a product such as Ditra. Sorry if he takes this wrong, but just because he has been doing it for years that way doesn't preclude industry standards or best practices. You will have problems down the road, guaranteed. Please let us know what he says.
 
  #11  
Old 07-05-12, 08:09 PM
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Originally Posted by DSOLSON View Post
Looking for thoughts on this project
Ceramic tile 17x17 tiles
Floor - 2x10 joists - 16" o.c., span 15'
3/4" T&G sub-floor - glued and screwed
Our contractor states he uses 1/4" A-grade exterior plywood adder with offset seams - so 1" total sub-flooring when done
Thin set bed directly on that surface - no hardi-backer/durock board.

So much of what I read states 1-1/4" min. (which adds little to strength of floor).

Is this risky? My contractor or tells me he has been doing this for over 20 years and has had no problems. Should I be concerned?
It's similar to what I have been tought how to tile. If you have at least a 1" of wood to tile on and the plywood is of a select grade it works and has not failed me nor many other carpenters contractors I know.
I'm synical about technics of tiling with all the new crap they have out now I'm old school and that's how they did it back in the day. So every forum online will tell you by the book but you ask contractors and tile setters they will give you different answes on how to tile correctly.
 
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Old 07-06-12, 03:41 AM
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As Isola96 will concede, I am sure, best practices have changed over the years. There is just a better way of doing it and today's construction methods dictate an isolation membrane. Is it "RISKY"?? You bet it is. Do you want to take the risk? Where will your contractor be in 5 years when you encounter problems? Have you contacted any of the contractor's previous customers to see if they have had any problems?? Your 15' clear span even with 2x10 gives rise to disproportionate flexing of the floor. It may or may not be a total factor in itself.
More of our tile pros will chime in here, I am sure, so give a chance for more opinions, please.
 
  #13  
Old 07-06-12, 04:06 AM
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I'm just being onest,not trying to confuse anyone by saying that the old way is the best and only way and to do it that way. you can drive your self crazy with what is out there if you think about it.
 
  #14  
Old 07-06-12, 06:49 AM
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What's to think about? Follow the best practices and standards and your odds of getting a successful outcome will be their best.
 
  #15  
Old 07-06-12, 08:31 AM
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Here we go again -

Laticrete, Mapei and Custom Building Products all list exterior grade plywood as an acceptable substrate for tile. The caveat is that the thinset must be a polymer modified product for a successful instal over plywood.

I've never used thinset of any kind on plywood so I have no experience, but if the thinset manufacturer says it's OK that's good enough for me.

Another thing to consider is that the OP's contractor appears to have a very good reputation

from the OP: "So many people I know have recommended this contractor as meticulous, thorough and one of the best in our area...... "
 
  #16  
Old 07-08-12, 01:40 PM
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When someone says they do things the "old fashioned way", they are implying that it's a better way than the "new" way. Well, the old fashioned way was a "mud-job", not double layer of plywood as the base. Those that tiled over plywood were considered hacks, most still are.

From mud we went to cement board in the '70's and more recently membranes such as Ditra. Although a real mud job is still the best method in virtually every case where it's practical, the other methods whether backer board or membrane are very good too. Tile over plywood is a method that fails much of the time. By "fail" I don't mean a total have-ta-remove it failure, I mean hairline cracks or a hollow sounding tiles here and there. I've seen failures where the homeowner thought nothing was wrong.

This guy might take his time and set the tiles nice n straight etc, but he is not a tile setter, he's a handyman using inferior methods. For one thing we should never use 1/4" ply anywhere in a tile subfloor sandwich. And using modified thin set is not a savior, you hafta use modified to get anything to stick to plywood.

You'd be much, much better off if you could find a reputable tile setter that uses Ditra XL, which will make the tile side and 3/4" hardwood the same level. Now you go from a poor quality method to premium method.

Jaz
 
  #17  
Old 07-08-12, 02:43 PM
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I personally have learned to adjust to newer meathods coming from we're I have started with tiling and flooring.
Most of it yes came from reading and learning from all these forums where infact Jaz has set me straight more then once, it's hard to go from what you were taught to some one else telling you that not the way of the "tile"
There is another way and it does work.

When I tiled on plywood I would always used 3/4" then 1/2" of ply over joists staggered both the correct way.
I have learned not to shoot this meathod out on forums because it sounds like I'm being a hot shot but it does work and if anyone wants to do it this way I don't see why not.

If you use the right plywood and yes modified thinset it will hold, using a 1" or 3/4" & 1/2 " of ply throws the span deflection out the window if staggered right no matter what you already exeld on your limit of span. Most tile setters don't understand this cuz your either a carpenter who can set tile or your just a tile setter who will no matter what use the cement board for a filler but it's like putting the word contemporary when are you need is faith in your tile work.

Again just saying I'll defend the meathod I was taught not saying to do it that way there are newer meathods like Jaz pointed out. I have explained the way it used to be done with both layers and if it's not done like that it give the old ways a bad rep
 
  #18  
Old 07-09-12, 03:12 PM
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I'll throw in my 2 cents worth You can tile over the correct thickness and type of plywood, but as Jazz mentioned, you won't get a good bond unless you used a epoxy thinset (which i don't know if they even make it anymore) the plywood bond will not last as long as over cement board, plywood is just too unstable. There are people out there that will set tile over plywood, even OSB board..Even luan, I know cause they beat me in bids all the time, but i refuse to install over inferior substrates. Believe me..it comes up easy when you have to replace it. Back in the 70's when I was learning the trade, they had a floor mastic, that you could set tile with, it was very flammable, you could use it over plywood or cement, and bonded better than todays modern mastic. Then came Latapoxy, it was a 2 part epoxy mixed with a cement/sand powder that held very well, but was expensive. Now there's modified thinsets, they don't hold as well on plywood, but you can buy various grades that hold better. I grew up using wire lath, sand /cement, soaked tile to set on a slurry of pure portland cement. The new methods are quicker/ better, less work with a better result, thats why tile is more versatle, and can be used in places not dreamed of a few years ago.
 
  #19  
Old 07-10-12, 05:22 AM
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Epoxy thinset is still available. I used it on two shower pans last winter per the pan's manufacturer's instructions.

Probably a good product but it costs more than thinset (unless you use the polymer additives) or mastic.
 
  #20  
Old 07-10-12, 12:39 PM
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My 2 cents as well. Yes there is an acceptable method for setting tile on plywood. It requires a minimum 5/8ths exterior glue tongue and groove plywood subfloor on joists at no more than 16" oc. It requires a second layer of plywood (underlayment) also a minimum of 5/8" exterior glue plywood. It requires a mortar meeting ansi 108.11. These are highly modified thinset mortars typically a quality drywet mortar with a latex additive. This method is for interior dry applications only. There are many other requirements to make it a safe good quality installation. The underlayment and setting materials are a fortune, and I cannot imagine why anyone would want to do it this way. Mud, cement board and liquid or sheet membranes are all better bonding surfaces for thinset and tile and will all yield better results.

If you use the right plywood and yes modified thinset it will hold, using a 1" or 3/4" & 1/2 " of ply throws the span deflection out the window if staggered right no matter what you already exeld on your limit of span.
This is nonsense. Adding plywood can help eliminate deflection issues between joists but does nothing for deflection issues along the length of the joists. Sistering the joists or cutting down the span with a support beam is how you address deflection issues if the joists are overspanned. I would suggest that you pick up a copy of the TCNA handbook, it cost about 20 bucks and pretty much has all the info you need.

It's similar to what I have been tought how to tile. If you have at least a 1" of wood to tile on and the plywood is of a select grade it works and has not failed me nor many other carpenters contractors I know.
I'm synical about technics of tiling with all the new crap they have out now I'm old school and that's how they did it back in the day. So every forum online will tell you by the book but you ask contractors and tile setters they will give you different answes on how to tile correctly.
I don't know any quality old school tile setters that set on plywood. It was always mud, mud and more mud. Thats the way I learned. As Jaz pointed out, those setting on plywood were considered hacks, and still are. There are guidelines out there for approved methods, and that is what we should be suggesting here. Telling someone its ok to set on plywood is really doing them a disservice without giving them the rest of the details that they need to set on plywood and wind up with a successful installation. We should be giving advice that will yield the best chance for a good quality installation.
 

Last edited by HeresJohnny; 07-10-12 at 02:37 PM.
  #21  
Old 07-10-12, 04:44 PM
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Originally Posted by HeresJohnny View Post
My 2 cents as well. Yes there is an acceptable method for setting tile on plywood. It requires a minimum 5/8ths exterior glue tongue and groove plywood subfloor on joists at no more than 16" oc. It requires a second layer of plywood (underlayment) also a minimum of 5/8" exterior glue plywood. It requires a mortar meeting ansi 108.11. These are highly modified thinset mortars typically a quality drywet mortar with a latex additive. This method is for interior dry applications only. There are many other requirements to make it a safe good quality installation. The underlayment and setting materials are a fortune, and I cannot imagine why anyone would want to do it this way. Mud, cement board and liquid or sheet membranes are all better bonding surfaces for thinset and tile and will all yield better results.



This is nonsense. Adding plywood can help eliminate deflection issues between joists but does nothing for deflection issues along the length of the joists. Sistering the joists or cutting down the span with a support beam is how you address deflection issues if the joists are overspanned. I would suggest that you pick up a copy of the TCNA handbook, it cost about 20 bucks and pretty much has all the info you need.



I don't know any quality old school tile setters that set on plywood. It was always mud, mud and more mud. Thats the way I learned. As Jaz pointed out, those setting on plywood were considered hacks, and still are. There are guidelines out there for approved methods, and that is what we should be suggesting here. Telling someone its ok to set on plywood is really doing them a disservice without giving them the rest of the details that they need to set on plywood and wind up with a successful installation. We should be giving advice that will yield the best chance for a good quality installation.

Then if anyone wants to tile then should get the tcna book before seeking advice. The reason tile dosnt hold to ply is that the trowel lines are crap and mix is wrong. You don't need te additives for thinset, don't need the milk mix, modified thinset mixed and trowel right and it's as simple as that it will hold BC sanded or plugged. There is nothing wrong with using a filler backerboard still needs to adhere to the plywood and T&G ply is for advantech users. I'm not going into detail on how to properly stagger ply on joists to avoid your deflection thory. This is we're carpentry and tile setters bump heads, tcna isn't a carpenters book and has alot that we carpenters dont agree with.
Have you made a bathroom from complete scratch from we're studs and joists need to be?...
 
  #22  
Old 07-10-12, 04:55 PM
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I think the dispute of tile over ply has gone on long enough.

OP has not been back in 5 days. He has enough info. If he has another question...he can start a new thread.

In other words..."knock off the arguing". Read the rules......
 
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