I have read through many forums and have come to the conclusion that if done right plywood subfloors are an acceptable way to lay tile. Why has the Ontario Tile Setters or this forum taken a position against this(expansion and contraction of wood). I laid tile in the bathroom before I did any research. I have laid tile in my bathroom over particle board over a year ago and not one hair line crack in the grout has appeared. I am still waiting for the day when cracks.

You've read through many forums?? Really ... name one that promotes installing particle board as acceptable surface for ceramic tile.

If you take away "Mortar Beds" .... if you take away "Ditra", .... if you take away "Cement Board" then use the next best thing which is ..... "plywood".

But why the hell would anyone choose to use something of lessor quality when there are better methods and products to help make your tile job last a lifetime? It makes absolutely no sense whatsoever.

Wood obsorbes moisture from the air and as the humidity changes so does the phyisical characteristics of the wood. It causes stress upon the tile installation and although plywood is better than OSB ... there are still increased chances of failure to the installation.

When your tile installation fails ... and it will, come on back and we'll help you redo it all over again. But this time the right way.

I do not promote particle board I am not a proffesional. Exterior grade plywood subfloor if done properly is it acceptacle? If no Why not? Why not make something last for a lifetime? Cost for one and most people change the appearence of their homes regularly. Now what are the chances of failure when dealing with exterior grade plywood?

Hi Matt
I've put a lot of tile over plywood...not of my choice mind you, but some contractors have been doing it that way for years and see no reason to change. BUT..you do get hairline cracks in the grout about 75% of the time...and if you do have a plumbing leak, or a tub goes over, or the dishwasher leaks..and the wood gets wet...you can have a major tile failure. I fact I've lost a whole kitchen because the water line to an icemaker in a frigde was dripping behind it an nobody noticed until the tile buckled. Sure you can do it if you want..but the average tile setter can't afford to go back and replace one of these jobs...so we make sure it's done right the first time. In your own home, it's a different story...the only one who is going to yell at you is your wife.

Matt ... I've never met anyone who regularly changes their ceramic tile, you'd be the first.

You'll have to excuse my attitude towards this, but if you don't care about the installation, why do any research? Just go to Home Depot tell them you want to save money and would like to change the tile every so often to accommodate your tastes and I'm sure they can help you out.

harry:

Still haven't answered my question. It seems like you want to avoid the issue. I just want to know if a plywood subfloor can be done and can last for fifteen years?

Matt

One of the poorest tile installation, longevity wise, is white bodied 4 1/4" set with a worn out V notch trowel and mastic on greenboard. In an installation such as this, often the grout is the only thing holding the tile on the wall. For each one of these I tear out, due to failure, I see several more in customers' houses that have no sign of damage at all. My mechanic lives in a house built in 1957 with the tile set this way. One bathroom is totally destroyed by water, the other looks just fine. I've rebuilt two bathrooms for his neighbors...again, total failure for the tile. Why has one bathroom lasted when three others are a total disaster? I have no idea.

Less dramatic are the results of tile over plywood and tile over vinyl installations....I see many that are done over these less than desirable substrates, holding up and giving no sign of failure. As Bri noted, we do see some numbers of these installs fail, simply because we see so many of them.

Results with cement board are even better, with old fashioned mud yielding the most durable installations. Do we see failures with CBU's and mud? Absolutely, but with such scarcity that it is worthy of note when we do see one.

I would go so far as to say that a poorly done mud job might last as long as, or longer, than a perfectly done plywood or drywall job.

You can tile over plywood, with SOME degree of confidence, but I would recommend using the best grade of plywood you can get, securely fasten it, and use the highest performance thinset that can be bought. Do all this and you MAY get 15 years with no problems. On the other hand, you may get problems in just a few months. One of my friends is an estimator for a multi-million dollar per year tile company in my area. They do a lot of tile over plywood for builders....1,000's of feet in a week. Some jobs come and go and there are no call backs. Other jobs come along where they end up tearing the entire installation out and starting over. It is almost never clear cut as to where the problem lies; but the one common denominator is tile being set over wood subfloors.

Rob is right.

Now Matt ... I'm not in a greatest mood today because I've been removing moldy, wet plywood from a bathroom renovation where the ceramic tile should never have been installed over plywood. The job is only 6 years old but the damage started only a couple of years after the installation. Visit the main page and click on "Current Project" and you'll get an idea of what can happen to wood, although this is an extreme case.
So I don't really have much to say other than I don't recognize plywood as a preferred method of preparing a final surface for ceramic tile.

..... especially in a bathroom.

Avoiding the issue? My God man ... how much more direct do I have to be?

Still haven't answered my question. It seems like you want to avoid the issue. I just want to know if a plywood subfloor can be done and can last for fifteen years?

Jeez-us Matt....how many times would you like us to answer the same question?

Thank you for your responses it is very much appriciated.