Flush transition with Ditra mat to wood floor [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-28-2015, 07:50 PM
Got some questions about putting new tile down that I couldn't find answers to when I looked on here. Anyways, redoing kitchen, joists in house are 16" apart with single layer plywood subfloor 5/8" thick throughout house. The adjoining room has hardwood that is 3/4" thick and would like an even transition if possible. Tile is 1/4" thick so I'm thinking I need the Ditra xl? Or does anyone think I should lay down new thicker subfloor and using regular Ditra to get an even transition? Thank you

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08-28-2015, 08:09 PM
Welcome, Justin. :)

Best place for you to look would be the Schluter Ditra website (http://www.schluter.com/6_1_ditra.aspx) for their recommendation for their product. They publish very specific requirements for many general applications.

But first you need to evaluate your joist structure to determine if it meets the requirements for a ceramic tile installation, with or without Schluter products. You can enter your information into our Deflectolator in the dark blue bar above to get an initial go/no-go reading on that.

That said, I would personally not install ceramic tile over nominal 5/8ths" plywood, 'specially old, probably damaged (what was the previous floor covering?) 5/8ths" plywood, on a bet, even though you'll find that Schluter will sanction that. Keep in mind that their testing was done with new materials, in perfect condition, near perfectly installed over joists with zero deflection.

I would recommend you install a second layer of plywood, then Ditra if that's your choice of substrate, then your tile, and then make the necessary transitions to your hardwood flooring. Tile to hardwood is one of the easier transitions to deal with.

My opinion; worth price charged.

08-29-2015, 09:12 AM
I did the deflection calculator about a week ago and if correct, I got L/ 828. Sorry I wasnt more specific about the floor. Before I removed what was on the kitchen floor it was, in this order, joists, plywood subfloor 5/8", then another sheet of plywood 5/8", then underlayment of cement board with tile on that. I have removed the old tile, cement board, and one layer of the plywood. Currently, the kitchen floor has the 16" joists with one layer of 5/8" plywood subfloor. I'm trying to get it to transition with dining room that has 5/8" plywood with 3/4" hardwood. So basically, Im trying to get my tile floor, Ditra underlayment, thinset, all to fit in 3/4" space. House was built in 1966 and it's a 10'x15' square room and wouldn't bother me a bit to buy new subfloor if needed. Just want it done right you know

08-29-2015, 09:27 AM
Entirely up to you, Justin. Everyone wants their new tile to be flush with their old floor coverings, but in remodel situations that's not generally feasible. I say make your subfloor suitable for your tile installation, then make your transitions to other floors as necessary.

My opinion; worth price charged.

08-29-2015, 10:40 AM
I totally agree with you there, above all it needs to be safe and done right. If I'm reading it correctly, according to schluters website, for 16" joists the requirements say minimum subfloor thickness - 19/32", 5/8" nom. tongue and groove" If I'm reading this correctly, couldn't I just lay the Ditra mat on top of the 5/8" subfloor that's already there?

08-29-2015, 11:23 AM
After re-reading your posts, I believe I'll replace the subfloor that's there currently. Do you think it's better to put down one thick piece of plywood or two smaller sheets glued and screwed together? I know Ditra comes in two different thickness so I could probably make either work and still have a safe install

08-29-2015, 12:53 PM
I would personally not ever start a subfloor with anything less than nominal 3/4" exterior glue plywood.

That deflection sounds unrealistic. You sure you're using the unsupported span of the joists and not the tile area or any such?

My opinion; worth price charged.

Tiger Mountain Tile Inc
08-30-2015, 09:38 AM
Hi Justin, I'll throw in an alternate point-of-view: Up here it's almost all wood subfloors. We go over 5/8" subfloors with 16" oc's all the time. Done properly they don't fail. There's nothing wrong with over-engineering but it sounds like your floor meets the minimum requirements.

You should be able to meet up with the hardwood with Ditra XL and 1/4 inch tile.

09-06-2015, 04:21 PM
I'm not sure what you mean by, "unsupported span of the joists and not the tile area or any such?". When I did the measurements for deflection, I measured
from the basement. The MATERIAL - "unknown", HEIGHT - top to bottom of board, WIDTH - top of board, SPACING - middle to middle of joists, LENGTH - from wall to middle of floor where joists end. That's how I thought I needed to measure but had never done it before. I'll measure again tomorrow just to be sure. Originally, it had laminate on subfloor, then another layer of plywood, cement board then tile, so surely I could put ditra and new tile down. Probably put new subfloor down on joists though.

09-06-2015, 04:58 PM
LENGTH - from wall to middle of floor where joists end.Mmmm, OK, but is the joist not supported in that place described as "middle of floor?" And if that's the middle of the floor that is to be tiled, what is the span of the joists on the other side of the middle?

09-07-2015, 08:43 PM
I'll try to swing by the house on my way to work tomorrow and take some pictures to upload on here to try and finure out the floor joists situation. I really appreciate the help though. I found a almost similar situation on a different site as well but not sure if it's allowed to paste a link

09-08-2015, 10:20 PM
kitchen floor, picture should be turned clockwise. I measured the joists and they are 16" o.c., 9 1/4" tall, 1 1/2" wide, and 9' 3" long. About half a foot on the right is the outside wall of house, on the left side the joists end about half a foot under the subfloor. The next picture is in the basement, under the kitchen floor where the joists end. I hope these make sense

09-08-2015, 10:28 PM
Basement floor where joists in kitchen end

09-09-2015, 11:58 PM
Tiger Mountain Tile - I was going to put new subfloor down but wondered if I should put 2 layers of plywood over joists and use 1/8" ditra OR just one layer of plywood (subfloor) and use the ditra xl? Curious if it would be better to have 2 pieces of plywood for a stiff and thicker floor under tile OR the ditra xl for more flex? I've looked for similar topics in the forum and couldn't find anything like that question. Also, any recommendations for plywood to get?

09-10-2015, 08:18 PM
Just a general question and couldn't find a similar post when I searched the forum: Putting down new tile on joists that previously had 2 layers ply, cb, then tile and adjoining floor that's 5/8" subfloor with 3/4" hardwood. Do you all think it would be better to put down 2 layers plywood & ditra OR 1 layer plywood & ditra xl? Seems like 2 layers of ply would provide a more solid floor but the 1 layer of ply with ditra xl seems like it would "flex" more since there's more of the ditra material? Going to go with one of these options and wondering what others thought, schulter systems said either would be fine

chuck stevenson
09-10-2015, 08:29 PM

It would be best to keep all of your questions in your original thread (http://www.johnbridge.com/vbulletin/showthread.php?t=117421). This way we can see what issues have been adressed.

09-10-2015, 08:36 PM
If you might want a natural stone tile, you'd need two layers of ply. But, what is the thickness of the first layer, and is it T&G? Was it glued down?

FWIW, with Ditra, the thinset creates pillars between the tile and the bottom of the pockets in the Ditra which is then embedded in thinset via the fleece on the bottom side. IOW, the height does not make the overall thing any more flexible.

09-10-2015, 11:17 PM
Meant for that to be a different thread, sorry, posted it now. Just to respond back to you though, it's 5/8", not T&G, just nailed to joists. I'm putting in porcelain tile but wasn't really asking for the install I'm getting ready to do. Was just curious which would be better because the double layer seems like you would have a more solid subfloor but the ditra xl seems like it would be better to use because the material is thicker instead of the 1/8" ditra.

09-11-2015, 10:30 AM
Justin, I combined that new thread here so folks can see what you're working on and get some context for your question. Such generally questions most always can be answered with, "that depends." Best to have context for the best responses.

And as you can see, even with context you'll get opposing views on which is "best." If either method meets tile industry standards and product manufacturer's recommendations, you get to pick the one you prefer. Easy as that. :)

09-11-2015, 12:35 PM
I called schulter systems and already asked them, they said I could also do either. Personally, I'm probably just going to do single layer ply with ditra xl. My question about 2 layers of ply & ditra vs 1 layer with ditra xl was more of a curiosity question. Seems like the double layer ply would be stiffer so possibly better...but I'm not an engineer haha

Tiger Mountain Tile Inc
09-11-2015, 09:59 PM
Hi Justin, if you're asking which floor is going to be stronger I think the answer is definitely a layer of 1/2" ply over the subfloor and then Ditra. But you would be good either way because they are both acceptable ways to build a floor. :)

09-12-2015, 07:28 AM
That's what I was curious about was either having a stronger floor or have the thicker ditra xl. I found a similar post that made sense about once it's uncoupled, it's uncoupled. I'm doing the single layer with ditra xl because Im laying porcelain on 16". Was just curious from a technology view. Thank you all