to cut or not to cut? the suicide tile floor job

[ShowerDude]

Just to make it clear , you can not install the uncoupling membrane directly on top of the wood planks .

valid point Roberto, may be common sense to US , but everyone else reading should get that point......

 

[ShowerDude]

The plank subfloor is clearly not recommended , even with the use of an uncoupling membrane -- and Without adding a minimum of 1/2 inch ply on top -- bridging gaps -- . I could also say that the T&G recommendation is also no respected , even with the addition of a ply on top .

Playing by the rules -- TCNA -- I would say you can not achieve the desired '' floor timed out with that wood floor. ''

Then there is the other option -- not sanctioned by the TCNA but "S" -- where the

D-W16-T-14

is shown . I would prefer to have blocked joints , instead of the T&G , but there is really careful work to be performed .

Do you want to take the risk ? "S'' is manufacturing only the uncoupling membrane ......the rest of the job rely on structural wood construction , mortar and grout products choosing and the so called experienced installer .

I NEVER use T&G in my subflooring. Always and only EXP1 BC ply 5/8" or better double layered crossgrain, glued screwd with silicone filled expansion joints and lapped joints, Just As John is always speaking to.....The smart safe way to go IMO.

 

[Sponsor]

 

[Eurob]

I see ........... I guess I am about to picture .... the real picture .

 

[Jadnashua]

Any unbonded mudbed needs far more thickness than you have room for to be viable. What people don't want to realize is that it can take years for an install to fail. Dimensional wood just moves too much, and a too thin mudbed will NOT compensate for it. Eventually, things get ground down and the integrity of the install goes south.

So, since you CANNOT meet the customer's desires with using any one of the know, tested, approved installation methods over the existing flooring, you're between a rock and a hard place. A way to tile it would be to install a layer of ply on top, but then, with any tileable substrate on top of that, you're going to be too high to meet the existing wood floor. So, you really have no choice but to remove the existing planks, or convince them they can live with a slight transition height difference between rooms.

Since most of these guys have me blocked, they probably won't see this, but it is the only known way to make it work. The existing stuff failed for one reason or another. Whether because it was not one of the approved methods or some other issue, it still failed. Even if you dropped something heavy onto a properly tiled floor, all it typically does is break a tile or two...it does NOT pop them loose from the substrate. That only happens when either the substrate is not rigid enough, or things got debonded. In this case, it seems it was plenty stiff enough, but seasonal changes in the dimensional lumber over time created a bond breaker, and allowed things to fail when (maybe) experiencing an impact that probably would not have been an issue otherwise.

 

[JohnfrWhipple]

Why did the old tile job fail? Do we have any idea?

That is just odd.

 

[ShowerDude]

Why did the old tile job fail? Do we have any idea?

That is just odd.

Read back a few posts John......My client corrected me, he just bought this home. it may just be damaged, history of floor is unknown really.

He wants this new floor regardless the history of this mosaic.

FWIW his bathroom has the same jersey mud and 50's mosasics timed out w 3/4 hallway wood floor.

It is indeed seemingly failing or also had a bowling ball dropped on it right in the middle/field.

These old jersey beds to thin and 60+ yrs movement. time to upgrade.

Ill be meeting this client in a bit here. see what happens..

thx for the input team.........

 

[Jadnashua]

A tiled floor may not actually break up for a long time after it becomes debonded - the grout will hold things together for awhile, but if you listen closely while walking across it, you'll likely hear a slight crunching sound. A 'Jersey Mud Job' doesn't work well over ply, let alone over dimensional lumber. While once in awhile, you may get one that seems to work, given enough time, pretty much all of them will fail.

You can laminate layers of plywood together, and if done right, it is stronger than two independent layers with just fasteners holding them together, but if you don't do it right (full spread wood glue, not a construction adhesive), you'll end up with a less than ideal situation. All of the industry tests are done just using construction adhesive to the joists and fasteners through the ply. Read up on the Robinson floor test to get an idea of how it is tested and what the results mean.

While a single layer ply, when installed properly, does meet the specs for a ceramic tile install meeting up to a residential rating on the Robinson floor test (when covered properly), it does require all long edges to be T&G OR installed with joint blocking to prevent that seam from deflecting independently.

 

[JohnfrWhipple]

RSCB - be careful with screwing to those old ship lap boards if any stay. By now they will be be brittle and can crack easy.

In much of my home I have these boards topped with new 5/8" plywood.

I have tiled over shiplap before to keep the grade nice.

Not in a large area however.

On this fireplace build I could have used Ditra or building paper, duct tape, expanded lath and Mapecem. I can assure you no Ditra was used in this renovation.....

The tile is 4"x4" Italian Marble. The floor is 110 years old.

The TV was not ready for the photo but fit inside the recess....

 

[ShowerDude]

 

[ShowerDude]

2x6 spf kd Cleats are in .....glued screwed w/ ext deck screws and pre-recessed for the cutout and 3/4 ply.....ill later hit these with some galvie Ringshanks....

 

[JohnfrWhipple]

Looks like you are building a tank RSCB. Any solid blocking planned?

 

[ShowerDude]

Looks like you are building a tank RSCB. Any solid blocking planned?

But of course... All tanks need blocking !!!

14-16 OC should do it....

I wonder why laticrete wont allow use of a medium bed over strata mat......any idea John?

 

[JohnfrWhipple]

But of course... All tanks need blocking !!!

14-16 OC should do it....

I wonder why laticrete wont allow use of a medium bed over strata mat......any idea John?

Not sure why RSCB. I would think setting the tile 1/4" above the Strata Mat should be fine. I skimmed out my Strata Mat install so I could install a small format tile. I noticed lots of hairline cracking no doubt the stress of walking on it over the areas where the mortar does not meet the ground.

Done a number of "D" jobs the same way back when I was using the "S" products. If you email technical at "S" they will outline how to install small tile over "D". It might take a few weeks to get the email.

If you want RSCB I'll forward you my email correspondence from Dale.

Could you not use a proper crack isolation membrane like NobleSeal CIS over say 1/4" cement board. Then pick any thin-set?

Arn't you installing a double 5/8" plywood subfloor? That by itself is tile ready.....

 

[Jadnashua]

I wonder why laticrete wont allow use of a medium bed over strata mat......any idea John?

Probably the same reason why Schluter doesn't allow a typical latex modified mortar over Ditra...it takes forever to dry. Throw in an extra deep layer, even with their small holes in the Strata_Mat, and it still could take a very long time for it to dry out. Until a modified (latex based) mortar dries, it can allow the tile to move and movement once the cement has spiked (cured), means it's not being held together by much.

Now, neither of these two tend to read my responses, but it is their loss...this may help the others who have a more open mind.

 

[ShowerDude]

Could you not use a proper crack isolation membrane like NobleSeal CIS over say 1/4" cement board. Then pick any thin-set?

good minds think alike......... John I am considering just that, only with TS .


Not enough room for double 5/8" I have exactly 1.5" to time out. I have 1/4" tile, recessed 3/4" ply with my cleat system. double 1/2" maybe..........I like single 3/4" and a membrane. but that requires a medium bed especially with TS.

How would you buildup in your opinion?? .....really no good way to decouple my top layer of ply from cleated 3/4" and joists.....tricky floor job here. rules all bent.

Now my client is having a party on saturday.....Entry way will be trampled on less than 3 days after tile set...now i need a medium bed speedset......!!!!! Adds to the challenge just slightly!!!!!!!!! good times. I will win.

 

[Jadnashua]

Not a single cbu manufacturer allows cbu over dimensional lumber, so pretty much regardless of what you put over it, you're entirely on your own. WIth a recessed 3/4" ply on the cleats, if you put your ply on top of it and only screw into the plywood rather than the joists, it would decouple it as much as if you had two layers installed on top of the joists with the second one only screwed into the first layer.

 

[JohnfrWhipple]

TS and CIS - Same Stuff different names and widths.

Party on Saturday - while they are having a reno..... SHUT THE FRONT DOOR.... lol

I'd stick to what you like. Lay down some temporary plywood over the install for the party.

What is the height you have from the top of the floor joist? 1.5" total.

I'd place your bonus layer of plywood (flush with joist tops) in and top jot with 5/8" sheathing. 1/4" cement board. Noble TS. Tile.

5/8" Sheathing + 1/4" cement board + 1/8" ts + 3/8" tile + 1/8" thin-set

 

[Eurob]

How thick would be the thin-set for the cement board ?

 

[Jadnashua]

Many cbu installation instructions call for 1/4" square notched trowels, so about 1/8" ultimate thinset thickness.

 

[Eurob]

How would you buildup in your opinion?? .....really no good way to decouple my top layer of ply from cleated 3/4" and joists.....tricky floor job here. rules all bent.

It is all about the engineering aspect , right ? There are St.Andre's cross bracing , block or lock in place the joists before cutting the planks or recessed plywood installation , flexible structural adhesives for subfloor plywood to joist connection ........ and then there are .............. uncoupling membranes .

How many rules do you think will be bent after all the engineering is done right ? Looking at the TCNA only ....oh well ...........