Tile over wood?? Country Plan pros unite!!

phalynx · March 27, 2008, 11:40:23 PM

Ok, I need to start thinking about flooring in the kitchen and baths. We would really like to do a tile in these 2 places. But I have read that it may not work at all because we are on a wood floor with some bounce. We have 2x12's 16" o/c spanning 19' with 3/4 T&G plywood subfloor. Can we put tile down? If not, is there something we can do to be able to put tile down? If not, can we put a fake tile down?

If yes to any, what's the best way to do it.

MountainDon · March 27, 2008, 11:56:31 PM

Go to the John Bridge / Tile Your World. Use their Deflect-O-Lator. You put in your info and it supplies a yes/no answer.

They also have a Q&A forum that specializes in tile and natural stone work.

If their calculator says okay, you should seriously consider putting down at least 1/4 inch cement backer board over your T&G plywood.

Not sure what you mean by fake tile?

March 28, 2008, 12:32:21 AM

Uh-oh. I got curious and looked at that Deflect-O-Lator.

It comes up with 2 thumbs down; no tile, no stone.

Ceramic tile is supposed to be limited to floors with L/360 maximum deflection. Your 2x12, 16"OC, 19" span, using Doug Fir or Southern Pine comes out at L/286.

If the joists in the tile area were doubled up it would pass muster. L/572.

phalynx · March 28, 2008, 10:08:34 AM

Well, because of the bounce, we were talking about putting a 3rd beam in the middle. This seems to make the deflection much better. I were thinking of just putting it up on blocks and not full concrete piers. Do you think this would make the difference?

MountainDon · March 28, 2008, 10:23:29 AM

I think if you do that you'll find yourself in the position of having the present foundation properly dug down beneath frost level, while having the supports for this extra beam located on top of the freeze zone. MTL, you will at some point end up with the central beam pushing up while the others sit there like they are supposed to.

I'm not an engineer but I believe that's what you run the risk of.

And that could be bad for more than just the tile

March 28, 2008, 02:27:05 PM

phalynx I ran into the same problem. I talked to John Bridge and they suggested that I placed a beam midways of my 16' span perpendicular to the joist run. Then put 1/2 ply and 1/2 backer board on top of the 3/4 T&G I have. I used two Milam beams 2X14 sandwiched and cut back into the block foundation on each end for support. In the middle I built a block pier. Haven't gone back to who I was talking to but it should work. I might Opt for 1/4" backer instead of 1/2" as the elevation is going to kill be meeting a 3/4" T&G hardwood. The tile is 1/2" marble.

John Raabe · March 28, 2008, 03:14:10 PM

According to the American Wood Council Span Calculator using 2x12s @ 16" o/c will meet the L/360 deflection that you want for a main living floor. I checked both Doug fir and Southern Pine. Both work if they are Grade No. 1 or Select Structural. No. 2 would be less rigid.

You would still want to have a solid backer board, of course.

phalynx · March 28, 2008, 04:09:26 PM

Quote from: MountainDon on March 28, 2008, 10:23:29 AM
I think if you do that you'll find yourself in the position of having the present foundation properly dug down beneath frost level, while having the supports for this extra beam located on top of the freeze zone. MTL, you will at some point end up with the central beam pushing up while the others sit there like they are supposed to.

I'm not an engineer but I believe that's what you run the risk of. And that could be bad for more than just the tile

We don't have a freeze zone here. I am not sure that will be much of an issue. But it might.

As far as backer board, do they mean putting down the concrete hardi-type board on the floor and then tile?

MountainDon · March 28, 2008, 04:23:16 PM

If there's no freezing I supose your plans could work. $:-\$

John made a good call there. What grade are your joists? The John Bridge calculator runs on the ssumption you have garden variety lumber yard #2.

backer board... stuff like this at Home Depot

Fiberock 1/4" 3'X5' FIBEROCK Aqua-Tough Underlayment Panels, Square Edge
There's also 1/2" and other brands like Durock

March 28, 2008, 05:09:38 PM

You could also stiffen up the 2x12's by installing one (or two) 2x4's on the bottoms of some/most of the heavily loaded joists. The stiffeners don't have to be full length ... 16, or 14, footers would do wonders. The idea is to "beef up" the bottom of the joist, mostly in the middle of the length where most bending takes place. Glue full length and clamp, followed up with screws or nails. A 90 deg screw driver drill is handy for this.

Are the joists currently blocked (bridged)? That adds stiffness also.

Of course, as you add the mass of the tile; and later furniture, etc ... the deflection increases, but the "bounce" lessens.

phalynx · March 28, 2008, 07:26:50 PM

We have Grade 1 2x12's. There is quite a bit of bounce. It feels like many houses I have walked into with spans of wood. I don't care much for it. I may try the beam in the middle. I will use the backer board too. Is the backer board intended to increase stiffness or just to adhere the tile?

Redoverfarm · March 28, 2008, 08:53:07 PM

phalynx what was told to me by Bridge is the ply is what makes it stiff. The backer just adds to and is used to adhere.

MountainDon · March 28, 2008, 09:28:45 PM

The backer board provides moisture resistance. And tile/thinset bonds to it very well. You can build a shower with it.

I've been told that tile on wood, plywood, OSB may work loose over time as the wood absorbs and releases water. FWIW, I've noticed most of tile work around here going over that stuff, unless it's going on concrete.

phalynx · March 28, 2008, 09:52:00 PM

Good enough. Makes sense. I guess I'll use it too.

March 28, 2008, 11:35:25 PM

We did tile in our other place - I'm sure there was more deflection but we had a double 1x3 t&g floor and sub floor.

The tile pro? told us to us a slip sheet over the wood to keep it from separating- the slip sheet is not glued down. No problems except where we removed a wall -grout works loose a bit, and the fact that it is around 10 years now and I haven't finished it. I'm testing the evolution theory...see if it may finish itself. hmm

glenn kangiser · March 28, 2008, 11:42:11 PM

This guy also says it will not work

http://forum.doityourself.com/showthread.php?t=152521

So -- if you are not willing to have the possibility of problems you may not want to try it.

They also made us use some kind of epoxy or acrylic thinset.

No guarantees it will work for you or that it won't take over 10 years to finish.

Okie_Bob · March 31, 2008, 04:48:54 PM

Hey Glenn, let me know if that evolution theory works out. I may try it anyway, looks like a good thing to do!!
Just a quick point here that I learned from experience recently. I used Hardie backer board in both of my baths and didn't realize that there are screws made specifically for Hardie backer board. I of course bought the wrong ones and couldn't get the heads of the screws completely into the Hardi board. I was sitting there looking at the little plastic box and it said in big bold letters to be used on Wonder board!!! So, next time I'm at Home Depot I go back to the Hardi board display and sure enough there are two different boxes of the screws, one says very plainly for Hardi board. I bought one box, took it home and sure enough, the screws went in slick as butter. Couldn't believe how easy they went all the way in. So, I took all the Wonder board screws out and replaced them with Hardi Board screws. Not a big deal, just something that makes life a little less agrivating.
Okie Bob

glenn kangiser · March 31, 2008, 10:03:09 PM

Just a few more year BoB and I think I will have success.

We mustn't rush evolution.

mvk · April 01, 2008, 04:47:29 AM

I've done a lot of tile some has been down for 30 years. Bounce will kill tile eventually or sooner. There was a lot put down around here by builders on the cheap 3/4" TG ply sub floor 1/4" Luan, it didn't last sometimes not even till the house got sold. I guess that that isn't code so they can't do it anymore. I would always like at least 3/8" ply underlayment if the floor didn't bounce or I wouldn't do it. I would probably use that cement board today that Don mentioned as long as the floor didn't bounce. Water is the other thing that kills tile. I think you need a lot for a long time though. Leaking toilet seals or around tubs and showers. But I think 3/8" or even better 1/2" ply screwed and glued held everything together. I don't think that the cement board does that, though it might be a better base for the mortar. I never had a problem with tile mortar holding to ply if it wasn't wet for a long time. Getting floor levels to match up is a consideration and I think that that was part of the reason for not enough underlayment. I would tell people that you would have to live with a threshold.

If your floor bounces and you can't put in a beam and posts I have had good luck by building truss beams right into the floors. It's a little bit of work and a lot of materials but seemed to work for me, don't know what a inspector or engineer would say though. You also have to deal with plumbing and wires, and headroom if in a basement. I build little 2x4 squares and screw and glue them into each bay in a line I then add two continuous plates to the bottom again screwed and glued. I then tie this all together by cutting sheets of ply and screwing and gluing these to both sides. I did a tile floor that was 16' by 20' like this. The truss was 18" deep from bottom of sub floor. It really made everything solid like it was one piece.

Mike

Okie_Bob · April 01, 2008, 05:24:49 AM

Mike, I think anything you do to keep the floor from bouncing would do the trick. I used 18" I wood I beams for floor joists throughout my place with longest span being 12'. I tiled two bath floors and so far no problem but, they haven't been down long. I noticed the instructions for the commodes tell you to put a bead of caulk around the bottom of the bowl before you set it. I don't do that. Instead I leave it open for a few days so that any leaks hopefully will show up on the grout lines darkening and then feel pretty safe that I have no leak. Then go back and caulk. Anyone else do that?
Okie Bob
PS: /Glenn, I was thinking about Jonsey's 'stumps' the other day when thinking about the steel tubing on another post.
Seems that would be the way to go as you could easily screw the stumps up and down to level any problems in the floor?

April 01, 2008, 08:06:13 AM

Regarding the 1/4" Hardi Backerboard and their recommended special screws. I found two alternatives that appear to have worked just fine for me. Instead of the "specialized" screws, I used 1 1/4" electrogalvanized roofing nails. They were left over from my roofing project, and the folks at a local wholesale tile and stone place (that is widely quoted in the local paper here in Portland and has a terrific reputation) said that these are a real good alternative to the specialized screws. The backerboard manufacturer also calls for fiberglass reinforcing tape that you use with the thinset on the seams--I noticed that the tape sold for $7 a roll. But the tape looked suspiciously like the drywall tape that they sold in another section at Home Depot. So I went over there and found that rolls of this fiberglass reinforcing tape sold for $2 per roll and you got more product per roll. What did I save? Perhaps about $ 15 to $20 total. I suppose if the slate I installed gets loose over the years, and I do some forensic work and find that the nails and the tape were the culprit, I will be proven to have been penny wise and pound foolish. Then again....

mt

PEG688 · April 01, 2008, 08:44:21 AM

Hardi used as tile substrate should always be thin-setted to the sub-floor. The nails act as clamps , roofing nails are fine , most guys thin-set it and staple it down with 3/8" crown staples. Once the thin-set is dry the fastener's are sort of "extra".

Brouncey floors , flexing floors , floor deflection all need to be removed / prevented / stopped.

I haven't followed this thread closely , BUT IF you have flexing between sheets (no T&G ) to thin of sub-flooring (overspanned ply) that needs to be corrected or your tile grout lines and or tile will crack.

Maybe overlay the whole floor with "another " sub floor , maybe IF the under side is open gusset the seams with glued and screwed 3/4 ply , what ever it takes , the "fix " now is cheap ,money once that tile is laid there is no cheap fix.

G/L PEG

glenn kangiser · April 01, 2008, 08:45:29 AM

I doubt you will ever have a problem, Mike.

MikeT · April 01, 2008, 08:50:27 AM

Thanks, Glenn and PEG. I indeed did use thinset under the backerboard as well as with the finish materials (slate in my case). There were two types of thinset--cheaper and more expensive. I opted for the cheaper stuff for the backerboard and more expensive for up top. If I had to do it over, I would have simply gone with the better/more expensive stuff throughout. Then I wouldn't have had two half bags of thinset and had to remember which is which.

Live and learn.

mt

azkateo · April 01, 2008, 01:00:00 PM

I've been in the home construction/remodel business for years and really, at the risk of being stoned to death by purists, I would urge you to look at the new vinyl flooring - not only is it a green product, but the 'stone' looking ones are pretty impressive. They would provide the look without the cracks. Alot of new home builders in the SW are using this product now that it has improved so much. Just a thought..