If you are looking for "correct' then the luan has to come up. Never have that under tile. The books says a minimum of 3/8 underlayment grade plywood, (no 1/4") then use Ditra or a 1/4" cement backer board, both are installed in a wet bed of thinset.

There are different types of thinset you use depending on whether you go with DITRA or a CBU.

You can install tile directly over plywood, but the hoops one has to jump through to "go by the book" is not worth the effort imo.

Can I put the Dirta or backer board over the luan and then tile?

No! Luan delaminates, warps and generally becomes unstable when exposed to moisture. It will be exposed to moisture when you install either ditra or cementitious backer board, both of which must be set with thinset.

Were you planning on something other than tile when you put down the luan? Just wondering the original purpose of it.

When I went to the tile store looking for tile that's what the guy told me to use. I had vinly sheet down and had taken that up and there was glue all over the subfloor. He said to put luan down and then the tile.

We put the luan over the subfloor. I then got my books from the library and started to learn more. I thought the guy at the tile store would know what he was doing - I never thought to questions him as I had never used tile before.

What the heck is luan for anyway?

Now you know... Don't ever buy and installed product from that tile store!!!!!!!!!!!!!!!!

"When I went to the tile store looking for tile that's what the guy told me to use"

I believe ya. Luan is somewhat similar to mahogany just much cheaper to produce. It can delaminate without a whole lot of help. The proper material is either an AC or BC grade plywood underlayment. Even with those two options the minimum thickness is 3/8"... no 1/8" or 1/4" plywood products underneath tile.

Having said that there are different grades of luan. Can you post back the APA stamping from the back of a sheet, and how thick it is?

I must seem like a complete dunce.

After the guy at the tile store told me to lay luan down I sent DH to Home Depot for luan. I did some internet research and read to lay the luan on the subfloor and nail ever 5" and to not meet up corners. Now it's down.

I looked on the floor for a stamp but could not see one (maybe it is on the underside). I did find a white sticker.

It says: 1/4 2x4 FSC Hardwood Ply. Jerry, what does that mean?

FWIW there is no give to the floor - very firm even when bouncing.

Thanks!

No, you don't sound like a dunce. The so-called professionals at the tile store - they sound like drooling idiots.

No one on here thinks you are a dunce, please don't ever think that. :-)

I don't know what FCS means, but what you bought does not sound like an underlayment.... sounds more like craft material.

It's already down now so the the only choice is take a chance on it, or remove it... I see no point in overlaying it with more plywood.

Forest Stewardship Council (FSC) is a non-profit organization devoted to encouraging the responsible management of the world's forests.

Here is a link that might be useful: FSC

DO NOT allow that luan to remain if tile is the objective. Just because it is already there doesn't mean it will work. To use the "OH WELL IT'S DONE NOW" attitude will only jeopardize the expensive tile installation. Luan has been specifically outlawed (by the tile industry) for use under tile installations.

You can find this information in the Tile Council of North America's Handbook For Ceramic Tile Installation. In the 2007 44th Edition the information appears on page 13, right-side column, second paragraph under the the word CAUTION in bold type.:)

I hate to tear this stuff up (very wasetful) but I may not have a choice. DH says it was in the Home Depot and labled luan.

I don't feel very I am managing the resources responsibly at this point!

The people working at the big box stores like Home Depot & Lowe's are clueless!!! They will lead you right down the road to failure 95% of the time. Heck, they worked in plumbing last week, and roofing the week before. Flooring is this weeks turn, to punt.

robynpa,

You may feel you haven't managed your resources properly but this isn't necessarily your fault. You were unfortunately mislead. On Internet Forums the advice coming from all of the box stores is most times misleading and inaccurate. A lot of us complain about this all the time. Check some of the complaint forums and look at the hundreds of complaints directed towards the incompetent big box stores.

At this point what you do is of course your decision but in my opinion to continue and not remove the luaun would be mismanagement of resources for certain. What happens when you proceed and spend more money and it all fails? Then what?

It's a tuff decision. Do you believe some faceless stranger on the Internet or do you believe the guy that three weeks ago was asking you if you wanted to super size your meal?

I believe what I have read here on this forum. The luan will come up and Hardi Backer will go down.

I most certainly will be back with more questions (each step of the way) as we start on our tiling project. We have never tiled before and I don't want to backtrack or waste any more time or money.

Thanks so much!

Make sure you install the CBU properly...read the instructions or research here how it's done or over at the John Bridges tile forum.

Bill Vincent monitors the Bathroom forum on this site, so that may be a place to post some of your questions.

Should change the name of this place to "The Vincent Web!"

He comes over to flooring on occasion, but his real haunt seems to be bathrooms! lol

robynpa,

I'd like to give you kudos for actually DOING something. I currently have two sheets of birch plywood sitting in my upstairs hallway, and a big roll of sheet vinyl in my living room. They've both been there much longer than I like to admit. And my kids are wondering if they'll ever have a bathroom floor.

Rip up that luan, and soldier on! I'm rooting for you.

make sure you use thin-set under it to take out the voids, screw or nail accordingly.

Here is a link that might be useful: Ceramictec

I'd rather had some professionals hired to check this out before you decide on antything.

Here is a link that might be useful: services

priestess, spamming is expressly forbidden in here. THat said, anyone using luan under tile is asking for trouble, even if you bury it under other layers. I've SEEN this stuff compress to half its original thickness in high traffic areas. One kitchen floor in particular that I ripped out and replaced, the floor had only been down for 6 months, and the luan in front of the stove was literally 1/8" thick, while just to the side of it, it was still 1/4". Additionally, luan isn't "like" mahogany. Real luan IS mahogany, and as such has oils in it that won't allow any kind of bond. Not with thinset, and not with mastic. This stuff just can not be used in any way shape or form, with ceramic or natural stone tile.

I know this thread's a year old, but after this person replying in the way she did, I felt it necessary to elaborate on what had been said to this point.

Hey Bud, if you come back here and see this, hatsa matta fuh you??? You no lika my web? :-)

For those reading along, do not follow Jim's advice. Luan is NOT an acceptable substrate for tile or redguard.

And he had 7 years to come up with the wrong advice, lol.

Am I missing something here? We had our house build almost 30 years ago (my hubby/dad) did much prep work before tiling was done in the kitchen. We installed luan there and have had no problems whatsoever. I am planning on tearing out my carpet in family room to install the wood look porcelain tile and was planning on doing the same type of prep. My sons were going to do the tiling. At times the internet can be as bad as the guys in the big box stores as you don't always know who is commenting. Any suggestions???? Thanks......

Carol, I'm glad you had success with your installation. I can say for sure that lauan plywood is NOT an approved tile substrate according to the TCNA, ANSI, or the plywood & redguard manufacturers.

Go to a box store and read the back of a bag of thinset. Luan will be listed under unsuitable substrates. There's your proof.

NO!

I have a small kitchen 7 x 9 which I took down to the diagonal wood planking sub floor. This is a 1st floor condo over a basement area. I get that I can't use luan, but you're all saying the thinnest plywood I can use is 3/8 inch? With a 1/4 inch backerboard. The actual floor space less the line of kitchen cabinets will be 5 x 9. Take away for the refrigerator another 2 ft square do I still have to use backerboard and 3/8 inch plywood? Please respond

Backerboard (CBU) merely provides a means to attach the tile to the plywood, a tileable surface. To reduce the thickness, 1- screw down the diagonal planks with decking screws, 2- screw down sheets of 3/8" plywood that is grade CC or better. BC is usually easier to find. 3- Install Greenskin or Tavy thin skin to the clean, new plywood 4- Install tile

I’ve put tile over luan, never had a problem, I pulled up the floor 15 years later, then pulled up the luan, it made it clean for the new floor I installed.

I am in process of that now did not know hope it holds up for 5