Hey Tile Guys

Jeff NWOH · Apr 6, 2015

Looking to tile a few rooms in our house/addition and am finding a lot of conflicting information on what is an acceptable subfloor for ceramic/porcelain tile.

We have 3/4" T&G plywood on 2 x 10 joists 16" OC spanning 10'. Some guys say this is good, others say add another 1/2" plywood on top. I have no experience with tile, and only want to do this once. I'd rather not add the 1/2" of height if I don't have to, but obviously I'd rather add it now and deal with it than do it over later.

Also, cement backer board or a membrane like Ditra?

Thanks, Jeff.

big daddy t · Apr 6, 2015

All the good tile guys I know use the cement board. I have been a contractor for 20 years if was getting my house tiled that's how I would have it done. Never put on plywood would although concrete would be ok. The membrane is most of the time used for showers.

Angle Iron · Apr 6, 2015

I know of two people that have porcelain tile and do not like it as the tiles break fairly easy. Don't know for sure but that6s what I was told.

Part Time Pete · Apr 6, 2015

If your plywood is in good shape, I would go with cement board over a layer of thin set. I will stiffen your floor up quite a bit.
Pete

casenut1 · Apr 6, 2015

You definitely want the cement board. And you want ceramic tile. Trust me , I have been a contractor for 35 years and in construction for 43 years.

big fred · Apr 6, 2015

Your 3/4subfloor is okay, but I'd add a tilebacker board. It will add a quarter inch.

VaTom · Apr 6, 2015

Substrate movement, if there is any, causes problems. Ditra helps to isolate the tile from that. That's not much span. If you jump on your floor, does it move?

All my tile was laid over concrete, so I won't offer much. I did not use Ditra, no need. Not unusual to hear tile guys opine that it should always be used.

The John Bridge forum link below will have all your answers.
Tile Experts

JohnDY · Apr 6, 2015

Please add the 1/2 inch cement board to the subfloor. You won't be sorry. this will help not having to redo the tile when it cracks or break loose. We always add the I/2 inch to our new homes.

Billy NY · Apr 6, 2015

Don't forget the doorway undercut, all those layers add up, on large jobs that's why there is a finish schedule on the drawings, so its coordinated and works. So many times I have seen an owner overlook that when making flooring changes towards the end of a job, that was not originally specified, even some intentionally, one sent 57 apartment entry doors back to be modified, just shook my head, its only money LOL !

DR. EVIL · Apr 6, 2015

Unless your floor joists are really big I don't think you can ever get ceramic tile to stick to wood sub flooring.

I put in a porcelain tile floor 4-5 years ago, made by SnapStone, got it at Menard's. It's expensive, about $5/tile, but the grout for the joints is the worst expense. It cures and is flexible. The tiles are epoxied to a molded plastic frame that snaps the tiles together and holds the grout gap consistent. The floor actually floats. No thin set or adheasive is put down at all.

I bought my own wet saw, seemed like 90% of the 12" x12" tiles needed a cut, but for my first tile job it looks great. I did the dinning table area, kitchen, hallway and front entryway & closet.

It will soon be five years and we have had no loose, cracked, or damaged tiles.

JerryS · Apr 6, 2015

If you're worried about floor springy-ness, and if you have good access underneath, you might consider some quick-fix way of additional underneath support to the center of the room.

Jeff NWOH · Apr 6, 2015

Thanks for the replies so far. I guess I didnt word my post quite right with regards to the cement backer board. I am planning on using it unless Id be better off with a membrane like ditra.

Sounds like my subfloor should be good? Everything getting tiled is new construction with exception of part of the kitchen. The existing part there will get new 3/4 ply over the existing 1 x 4 T&G subfloor(2 x 8 joists on 10' span).

JML755 · Apr 6, 2015

I'm redoing our foyer/hallway/bath/laundry room right now. I put 8" ceramic tile over 1/2" backer board on a 3/4" sub-floor 27 years ago. No cracks whatsoever in all those years in this high-traffic area with lots of stuff dropped on it over the years.

Using an air chisel to remove the old tile, leaving the backer board and putting 12" ceramic over it. Ceramic is fine for indoors. Porcelain is only needed outdoors due to its water imperviousness (sic?). Otherwise, they're basically the same stuff. Biggest mess is the fine dust from the demolition. Even with sheets and plastic segregating the work area, the dust seems to migrate. Wife and I will just "spring clean" the house when I'm done.

Figure it's a 3-4 weekend job to do 250 sq ft in sections so we can still get into and out of the house. To answer your question, definitely use cement backer board. Otherwise, you'll regret it.

Super-H-Mike · Apr 6, 2015

I just redid my bathroom and added a tile floor, I did tons of research and what I found was MOST guys recommend at least a 1 1/4 subfloor over the joists,then thinset and a layer of 1/4 or 1/2 cement board,then more thinset and the tile. This is how I did it and came out really nice and solid. The extra height is a drag as I now have a small lip going into the bathroom. It was a lot of work overall , but I only wanted to do this job ONCE in my lifetime !

showcrop · Apr 6, 2015

I was planning to put ceramic tile down in the kitchen until I found out that it has gone out of style. Everybody is using wood now. Ceramic may still be preferred in the bathroom.

MarkB_MI · Apr 6, 2015

If the floor joists are accessible, you might want to sister them. That will cut your deflection in half.

Quarter-inch backer board is a must. It's not going to do much to reduce overall deflection, but it will stiffen up the flooring anywhere it's not directly supported by a joist. My preference is Hardi-backer.

Chief 83 · Apr 6, 2015

My wife just had the majority of our house done. Couldn't complain much since I never hear a word about what I spend on tractors. We have the 1 1/8" wafer on our floors. House is about 19 years old with no squeaks, sags, or soft spots anywhere. We spoke with a number of tile guys and almost all (had one that could only see the $ signs) of them indicated that the paint on membrane would be just fine and there was no need to go with the concrete board under. That solved a number of issues where tile would come up against carpet and worse yet a vinyl floor as far as height issues. Well the floor has been down now for about 9 months and we haven't had a single issue. All joints and grout lines etc are perfect. So I think you would be ok if you don't have any sagosis (is that a word)with your current sub-floor. If you do, you best use the concrete.

omahagreg · Apr 6, 2015

I had a ceramic floor crack several years ago. Only had 1/4" durock and 3/4' subfloor underneath. Florida Tile rep said you MUST have 1 1/4" of subfloor before any durock, so it wont crack!

TimnSEVA · Apr 6, 2015

I ALWAYS use 1/2" cement board over a 3/4" subfloor. Apply correct thin-set, lay cement board and screw to sub-floor per manufactures specs. Apply thin-set and install tiles. We only use Ditra in large open areas with a TJI floor system and 1" plus sub-floors.

Jmo1999 · Apr 6, 2015

You can just put backerboard down with thinset. no need for another layer of plywood.

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