Ditra install

[daion]

sorry newbie here.don't know how to post
I'm trying to find out what is stronger for the floor.Ditra or 1/2" cement board? Have 1/2 t&g ply.But, have height issue w/ adjoining floors.Floor is pretty solid.Extra bridging,glued,nailed.Family room below w/ drop ceiling.
ANY help would be forever remembered.

when the storm starts,the drops start dropping,
when the drops stop dropping,the storm starts stopping!
dr.seuss

[cx]

Welcome, daion. Please give us a first name to use if that's not it.

You don't want to attach your question to an unrelated shower thread, so I've moved it here and started you a project thread. Please ask all your questions here. We can change the title at any time if you'd like.

You don't depend upon the tiling substrate for any structural quality in your tile installation. Either the membrane or the CBU requires the same subflooring and joist sturcture.

Your subflooring is not adequate for either, but first we need to find out the rest of the story. You must know the type, condition, size, spacing, and longest unsupported span of the floor joists.

Then let's verify the actual type and thickness of your subflooring. It would be very unusual to have half-inch T&G panels.

My opinion; worth price charged.

[daion]

Thanks for directing me to the correct location.
I was at error w/ the thickness of the sub.It is 3/4 t&g.I installed 2 xtra solid bridging runs and the longest span is approx. 11'.I glued and air nailed(6" pattern)
ron

[Mike2]

Hi Ron. What size joists and how are they spaced?

See the Deflecto tool on the blue bar towards the top of the screen. Go there, input your joist data, then tell us what you get.

[Dave Taylor]

Well..... you've given part of the information needed to help us help you answer your question.

Open the "Ta Da" 'Deflecto' tool up top this page.

This tool will help you calculate floor substructure (joists below your 3/4" T&G) "deflection" (bend) number........ which helps determine if your substructure is within constraints deemed necessary to maintain a tile covering.

If you've already used this "Deflecto" tool to calculated your floor deflection "L" number..... what deflection number did the tool generate for you?

EDIT: That Mike/Mike beats me to answering posts with increasing regularity.
Mebee" I need to loose weight.

What he said:

[daion]

Oh Yeah
I'm l/377.I'll be using 13x13 porcelain.Thanks for the instruction so far

[Dave Taylor]

Consider using the Ditra, Ron...... it has about a 1/8" heght installed.

If you do use CBU..... 1/4" is sufficient as opposed to 1/2".

In all cases (unless your subfloor IS mucho sturdy).... I would consider more plywood underlayment...... 3/8" minimum..... 1/2" much better.

[daion]

some of the joists were crowned,so I used a planer(as best I could) to achieve flatness.There is an area that will most likely need to be leveled a tad.OK,so I missed one Ditra for the ply is modified? What should i do for the area I put leveler on? The modified is for the WOOD only application and over cement it should UN modified? I'm working off of memory now and it's been two weeks scince my conv. w/ ditra. They told me of the "modified and unmodified" condition.What are my options in that erea

[daion]

Can thinset be applied a little thicker under Ditra to compensate for a dip in the floor?
Does the thinset have to be "notched" or can the Ditra be laid on a flat "leveler"type of thinset application?
I have a 1/2" dip from my last joist-to the wall (16").I have already put some Henry on other spots.Well aware that I have to switch from modified to unmodified in these areas.I used the Henry assuming it's ok because it's portland based(concrete?).And for the fast setup.
I'm applying the Ditra over plywood with modified.Hoping I can Get away w/o having to get more Henry.
I'll be using 13x13 porcelain.I'm assuming,from what I read in the threads,I shoulds butter the back of the tile as well?
Is a 1/4x3/8 sq. notch the right one?Thanks for any input.
I'm a newbie to this site,and tile.Couldn't have done it w/o the help I've gotten already.

[daion]

Ditra install

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Can thinset be applied a little thicker under Ditra to compensate for a dip in the floor?
Does the thinset have to be "notched" or can the Ditra be laid on a flat "leveler"type of thinset application?
I have a 1/2" dip from my last joist-to the wall (16").I have already put some Henry on other spots.Well aware that I have to switch from modified to unmodified in these areas.I used the Henry assuming it's ok because it's portland based(concrete?).And for the fast setup.
I'm applying the Ditra over plywood with modified.Hoping I can Get away w/o having to get more Henry.
I'll be using 13x13 porcelain.I'm assuming,from what I read in the threads,I shoulds butter the back of the tile as well?
Is a 1/4x3/8 sq. notch the right one?Thanks for any input.
I'm a newbie to this site,and tile.Couldn't have done it w/o the help I've gotten already.
__________________

[daion]

tried last night but gave uo waiting and went to bed.1hr.15mins

[daion]

hello,
i was wondering if i can put modified a little thicker to make up for a sag in the plywood floor,under the ditra?Does ditra have to be laid on a "notched thin set or can it be forced into a flat thinset? It's 1/4-1/2 " from the last joist to the parrallellell wall.Is that even a word? Somewhere about 18 in.
I put some Henry in other areas.I'll have to use unmodified where there leveler is and modified for the bare plywood.
The HD where I live TOTALLY stinks! The Henry was all they had,and being portland based,figured it would work.Hope I'm correct
#2 I'll be applying 13x13 porcelain.What is the recommendation on trowel size?
I've tackled almost every project in my last 2 homes. This is my first tile job.I love the diy thing,but I'm learning to leave the tile to the tile guys.To many factors to go wrong.I couldn't have gotten this far w/o the help of this forum!Any input is certainly welcome
If anyone needs a highrise or a bridge built,I can do that.

[daion]

I delete the forum address from my contacts now.Three times ,over an hour wait.Can't wait no more.The initial post must have been a teaser.

[cx]

Sorry, Ron. Most all of our free help hereabouts have real jobs that keep them away from the forums for unreasonable amounts of time, I agree. But they do the best they can to keep up when they're here.

[Mike2]

Ron, it's best to level the floor and let that set up before placing Ditra down. A 1/2" thickness build with thin-set is a little too thick. Depending upon how big this area is, I think you'd be better off using a cement based patching compound.

What was the Henry's product you used? Could be you just need more of the same.