I have just finished re-grouting several sections of our new kitchen tile floor for the third time and am beginning to wonder where I have gone wrong.
I am using a 12″ x 24″ porcelain tile with about a 3/16′ grout joint ( I used two nickles to set the grout width). I have used this size tile and grout joint together successfully in the past so I am not sure what is different this time.
The one thing that is new to this project is that I used a plastic sheet membrane over the existing wood sub and finished floor (1 1/2″ total thickness). The product is called (Schluter Ditra) and it was reviewed positively a few years back in FHB instead of the hardibacker I usually use. I used the new product because I wanted tile but also wanted to avoid the 3/16″ in extra height associated with hardi backer especially at the threshold change at the Oak dining room adjacent to the kitchen.
I followed the product installation directions for the install but keep having the grout line failures and I am afraid that the problem will continue. It could be that I got a bad batch of grout but I wonder if any others have used Ditra and have had good or bad experiences or suggestions other than taking out 250 square feet of tile.
Replies
Never had any problems with properly installed Ditra.
Grout failures are the first sign of a floor that flexes too much. Your floor sounds thick enough, but that doesn't guarantee a stiff floor. That's the first place I'd look.
You might also want to try checking out the John Bridge forum -- excellent resource for tile-related questions. http://www.johnbridge.com/
Mike Hennessy
Pittsburgh, PA
Man that's a lot of nickles. And how do you keep from stumping your toe on them in the morning?
I agre that it sounds like the floor is flexing a little too much. Do you know the floor joist size, span and spacing? Does the china cabinet rattle when you walk past?
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Edited 2/4/2008 7:40 am ET by FastEddie
Yeah it was a lot of nickles but they are easier to place and remove than spacers and by tossing them in a bucket as soon as I pull them I can re-use them or spend them - try that with plastic spacers.
The joists are true 9" x 1 5/8 old stock with a 12' span placed 16" o.c.
The grout lines are breaking in a couple of places in the traffic pattern but not at center of span. The joist are exposed in the basement and I wondered about placing additional blocking as they are only blocked at the mid point and only with 2"x4" cross bracing.
There is a little bounce to the floor throughout the kitchen as I walk by but nothing really rattles. It is an old (1938) house so I don't suspect settling is the issue. I have tiled in several other areas of the house without trouble, but those areas did have less than the 12' joist span in the kitchen.
CJ
There is a little bounce to the floor throughout the kitchen as I walk by
Your floor specs look good so there should be no noticeable bounce. Maybe some of the joists are not bearing at the ends due to (old) settlement? It seems that some part of your floor system is loose somewhere, allowing movement. Something to check anyway.
What kind of sub-floor did it have?
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Subfloor is diagonally placed 1 x 8 pine surface nailed to the joists, with 1x4 T&G fir blind nailed to the subfloor on top.
There was another layer of 1/2" chip board on top of that that was stapled over with old linoleum tiles. We stripped off the chip board and applied Ditra and thin set under the new tiles.
This is the old section of the kitchen. Where it meets the new addition the subfloor is two layers of plywood in most sections and one area had exposed concrete. The transitions are where I expected problems but so far I haven't noticed any.
CJ
Do you have any problem over the plywood.Floor tiling with a backer board is only speced over OSB/PLY, not individual board subflooring.Might want to contact Schulter (sp?) tech support and see what is required for ditra..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Those numbers calculate to about L/500 so porcelain should be ok. "Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Yeah, but the flooring and subfloor are flexing between the joists, and/or are just "bouncing" over the joists under foot traffic because the nailing is inadequate.
I immediately thought what some others said about the floor flexing. Is the grout only failing in certain places. or everywhere? If in certain places, I would say that's evidence of flexing. If all the grout is turning to powder of something, then I'd suspect the grout, but I don't see how the membrane under the tile could be at fault. In fact, if there is flexing, it may even help (a little).
Before I tiled our kitchen floor ('37 house), I emptied about four sticks of ring shank nails through the ship lap subfloor and into the joists. They were very stingy with nails back then. Did you happen to notice whether the subfloor was well nailed?
The floor had a few squeaks before I tiled it so I did re-nail in those areas - coincidentally these areas seem OK now. The two main spots that are plaguing me at the moment seemed tight so I didn't re-nail there at all.
I use the space below as a workshop so I hope to keep it as open as possible but I could shorten the span by a couple of feet by re-building my tool storage on one wall as a built in with a bearing beam. That would reduce the span to about 10' max.
If this fails, I wonder about reefing out the grout in the failure areas and using an epoxy type grout. Do you think the Ditra would give enough float to avoid cracking the tile if I used an epoxy grout?
CJ
My guess is that the subfloor+flooring has too much deflection, caused by loosening of the nails over time. My own house has 1x8 diagonal floor sheathing with 1x4 T&G fir flooring over, and I would not tile over it, Ditra or otherwise. I would remove the 1x4 and replace with 3/4" T&G plywood subfloor, and then tile over that. You might have been able to get away with screwing thru the 1x4 into the joists, with screws closely spaced, and sucking everything down tight.
deflection- more renailing into the joists, then lotta screws to pull the layers tight wudda done it can i have the crock of nickels? i have ciphered that there was $42,000 worth of nickels on that job
"I'm not responsible for my actions."
Actually only about 3 rolls of nickels were used on the total project. Floor was tiled in three sittings - This is my home rather than a clients so I only work on it part time.
Short of ripping up the tile in the problem areas, you guys have any advice / ideas about stiffening from below. I suspect I am only putting off the inevitable but it might be worth a try.
CJ
try ripping 3/4" cdx plywood to 9" , glue and nail to each side of floor joist in center of span ( 8' long rips) this should help keep the joist from deflecting and keep your basement open. you could even double up the plywood on both sides if it has a 'lot of bounce"
ok, u keep the nickels but if u ever switch to quarters let me know it's still deflection, the renailing w ringshanks like others said, and then screwing the underlayment w/ linoleum tight to the planks wudda done it
but here's another thing, personally i think the schluter product is going to start failing x number of years down the road on a lot of projects.... because the great sin of plastic, the "plasticizer" chemical which makes plastic just that, able to be formed / supple, is cheap, not long lasting and will chemically break down and go brittle one day
and then deflection is going to take its toll on the brittle product which is combined (if properly installed) with unmodified thinset which has limited give i know everyone loves this stuff i've used it too, but give me Hardibacker properly applied, or AC plywood glued and screwed to a tight subfloor anyday to underlay tilework
well, i guess a lot of people who consider this blasphemy are jumping into their pickup trucks right now and heading up here to King Gambrinus, Wisconsin to toss me a beating i'll throw a 'possum on the barbie and keep the cheese cold... not government cheese neither, the real Wisconsin stuff the stuff dreams are made of
"I'm not responsible for my actions."
I'd be willing to bet there have been arguments about that before, But would love to learn more about it. Maybe another thread?
yup, fistfights will break out over dissin' Ditra, but it's true plastic has a limited shelf life because of the plasticizer dying of old age not knocking schluter products which i've used for years w/o any trouble not knocking ditra, either i like it, but do see it being installed wrong a lot...
wrong mortar, no mortar under it, not leveling uneven floors to specs that schluter recommends, even saw one guy skip filling the "honeycomb" with a scratchcoat; he just mortared with a notched trowel onto the orange and set tile in one operation
"I'm not responsible for my actions."
Not gonna throw punches, bacause you're not wrong. I'll instead just throw a line or two...If the Ditra was exposed to UV (common source being sunlight) or repeated heating cycles, you'd be correct. But with no exposure to sunlight, significant degradation will not be a problem.RFH temperature cycles are not enough to cause significant plasticizer migration.Will plasticizer still migrate out? Yup. But not significant amount to cause material failure.
Edited 2/6/2008 6:10 pm ET by Mongo
What about the lime and portland? Would they degrade plastic?
No. Not a worry.
i wonder if air bags will also fail
Bill got it.
Ditra shouldn't go over a wood plank subfloor. Wood planks move, the bond between the ditra and the planks fails, the Ditra fails to act in its intended purpose, then with foot traffic the tiles shift and the grout fails.
The failed grout is simply a symptom of a failed installation. Epoxy grout won't be a cure, it'll be a band-aid.
Were you to use epoxy, sometimes the epoxy can be stronger than the tiles. Future flexing may cause the tiles to actually snap, especially with large format tiles like yours.
Mongo
Boy what a Homer Simpson moment!
The local big box guy said this was the "perfect product" for our needs. I just got off the phone with Ditra and they said the same as you.
Rather than rip out a thousand dollars worth of tile, I think I will try a few band aids in the problem areas and see if I get lucky.
Did someone say throwing good money after bad?
CJ
I didn't see in your post ? what kind of grout did you use?
I used polyblend sanded grout.
No additives. just water.
CJ
Not a lot of happy thoughts for your problem.
Have you looked as somebody above gives a little fat foot action to see if your getting movement. Run a string to be accurate.
I've used the poly blend for color reasons but my first choice is Mapie(sp)
I just looked at their web site and they have a pretty good looking product warrantee
http://www.custombuildingproducts.com/ProductCatalog/Grout/PolyblendSandedTile.aspx?user=arc&lang=en
Thanks guys
You are comming up with lots of good questions.
I did string line last night and have observed very minimal deflection when people hop on the kitchen floor. It is actually easier to see in a pitcher of water on the kitchen island as small ripples. So some deflection is occurring.
The grout is only failing in two areas that I have found so far. Unfortunately, both are in very visible areas. I am considering adding some support below to stop the minimal deflection in these areas to see if that makes any difference.
I did look at the Mapei site and wondered about using their sanded caulk to create an expansion joint at the mid point of the span to see if that would better accommodate the need for movement. Thoughts?
As to comments from others..
I did use unmodified thin set for the Ditra to subfloor and for the Ditra to tile bond. I am fairly confident that I had the mix correct and did not re-water during installation. I used a square 3/8 trowel for both applications with back butter on tile. Let cure for a full week before grout application not so much out of drying concerns but I got busy and couldn't get back to the project for about that long.
CJ
I will still look at trying to fix problems from using a board sub-floor.cut plywood panels to fit BETWEEN the joist.Then run screws through the ply into the sub-floor so it becomes more unified moving as one rather than each board moving independently.Use LOTS of screws..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I did something like that once to fix squeaks in a face-nailed hardwood floor. The squeaks were concentrated in a few areas and the subfloor was open to view below in the basement. It was oak nailed over 1x8 subfloor.
Got two 4" holesaws. Installed the center drill in one and not in the other. First, start drilling up thru the subfloor with the hole saw w/ center drill. As soon as the hole saw starts cutting, switch to the one without the center drill. This makes it possible to remove a 4" plug of subfloor without drilling into the bottom face of the flooring above.
After drilling out a strategic series of plugs this way, I glued them back into place with subfloor adhesive, and then screwed and glued a piece of plywood up against the bottom of the subfloor as you describe. The glued-in plugs help to join the flooring and subfloor, the plywood and glue help to stabilize the subfloor.
I don't know if this would help the OP. He needs screws thru the subfloor into the joists. My method helps stop flooring from squeaking as it rubs up and down on its nails.
Q. What type of thin-set mortar should I use when installing Schluter-DITRA?
A. The type of thin-set mortar used to install Schluter-DITRA depends on the substrate material. For example, to set DITRA over plywood or OSB, a modified thin-set mortar meeting the requirements of ANSI A118.11 is used. To set DITRA over concrete or gypsum, Schluter-Systems recommends an unmodified thin-set mortar meeting the requirements of ANSI A118.1. Please consult the Schluter-DITRA Installation Handbook before beginning your tile project to confirm the proper materials selection.
There are lots of systems out there with plenty of latitude - DITRA over old wood subfloor isn't one of them. The greater movement in a non-continuous subfloor combined with the incorrect material for setting the DITRA is probably where the problem lies. This is exacerbated through the use of a large tile and small joints.
I would discuss this problem with the DITRA rep and consider the possibility of regrouting with Laticrete SpectraLok Pro grout ($mall ouch) or re-tiling (lot$ of pain).
Jeff
Edited 2/7/2008 8:12 am ET by Jeff_Clarke
Jeff,
Once again, you've hit the nail on the head.
The floor can be stiffened so there is zero deflection. But if the wood planks have any seasonal movement at all, that movement can break the bond between the wood planking and the unmodified thinset used to bond the Ditra to the planks.
To me any improvements are suspect. Stiffening the floor could help, but in all practicality if the Ditra bond has been broken it's still a flawed floor.
Oh, and off topic? Your kitchen cabinets are gorgeous!
Thanks!
Jeff
You have l/520 or so - can't be deflection.
Personally, I think 3/16" is a pretty narrow joint for tile that big. Plus - sorry to call you on it - (2) nickels don't make 3/16" - more than 1/8" but only just. I'm thinking that's not enough material in a joint for large tile.
Did you use a 1/2" square notched trowel and back butter each tile?
You might consider using a different grout (I like Laticrete SpectraLok Pro) - it's unstainable, but also pretty expensive and a little harder to work.
eta - did you bed in latex-modified thinset? This product is required to adhere the Ditra to wood, but NOT recommended to bed tile - you might want to read this:
QUESTION
Can ceramic tile, including porcelain tile, be set on Schluter¯ -DITRA with latex-modified thin-set mortar?
ANSWER
We DON’T recommend it. Here's why:
Latex-modified mortars must air dry for the polymers to coalesce and form a hard film in order to gain strength. When sandwiched between two impervious materials such as Schluter¯-DITRA and ceramic tile, including porcelain tile, drying takes place very slowly through the open joints in the tile covering. [According to the TCA Handbook for Ceramic Tile Installation, this drying period can fluctuate from 14 days to over 60 days, depending on the geographic location, the climatic conditions, and whether the installation is interior or exterior]. Therefore, extended cure times would be required before grouting if using modified thin-set mortars between DITRA and ceramic tile, including porcelain tile. If extended cure times were not observed, the results could be unpredictable. This is even more important to consider in exterior applications that are exposed to rain as there is the additional concern of latex leaching.
ADDITIONAL NOTES
15 years of field experience and testing by the Tile Council of North America (TCNA) support the efficacy of using unmodified thin-set mortars to bond ceramic tile, including porcelain tile, to Schluter¯-DITRA in both interior and exterior applications. See relevant testing data on page 26.
Remember, the type of mortar used to apply Schluter¯-DITRA depends on the type of substrate. The mortar must bond to the substrate and mechanically anchor the fleece on the underside of the DITRA. For example, bonding DITRA to wood requires latexmodified thin-set mortar. Additionally, all mortars (modified and unmodified) have an acceptable temperature range that must be observed during application and curing.
Jeff
Edited 2/5/2008 8:43 am ET by Jeff_Clarke
What would be good joint for 12x12 slate ?
IMO 3/8"
Jef
did you add water to your thinset cement after it was starting to set and continue to use it? (bad). Did you let the thinset skin over before you set your tiles down?(bad) Did you mix the thinset to a too thin or too thick consistency? (bad) Was the ditra set down with a v-notch trowel(good) and was the thinset not skinned over when you laid the ditra.
Might not be a deflection issue
How about trying the color-matched caulk? It's available in sanded and non-sanded to match just about every color of grout. This would stay flexible. Not sure how it would stand up to heavy-duty floor use and washing. You might have to re-do it every so often, but I bet it would work.
Bill
I have been reading and re-reading John Bridges blogs and others about silicone modified vs latex sanded grouts. It seems like a lot of folks really hate the Mapei sanded caulk because of shrinkage and love the silicone despite the cheesy shiny plastic appearance.
My question is, if Mapei caulk is so bad, why do they still sell it - kinda sounds like Nestle Strawberry quick - nobody would buy it twice!
I met with my local building official today and worked through the calcs on adding a plywood composite beam 36" in from one edge of the basement with supports every 8 feet. He believes we could cut deflection by 40% +/- for the cost of 2 sheets of plywood a couple boxes of nails and some glue. Seems like it would be worth a shot.
He suggested adding some latex to the grout after the beam was installed in the bad areas and seeing if that makes any difference.
CJ