Hello,

I have installed radiant floor on my ground floor kitchen/dining room/living room of a hundred year old farmhouse. The floor is 2x10 on 16" centers. I put 1/2" plywood over 1" T&G Maple then 1 1/2" of concrete over the subfloor. I cut 3/8" deep tension cracks in the concrete at a maximum distance of 6 feet due to kitchen island, corners and protruding walls.

I am going to put Ditra down on the floor as a decoupling membrane and to have the tile meet up level with the 3/4" HW that is going down in the living room. Tiles are 20x20" Ceramic.

My question is do I fill these cracks with some kind of crack isolation membrane before putting the Ditra down? I have been told that I don't need to but questioned that answer. If it is needed what do you recommend?

The concrete floor was power troweled and is very smooth so I was also wondering if I needed to do some kind of surface prep before I put the Ditra down?

I have one more question about the thinset (servoflex-Trio-SuperTec). It has been stored on a pallet in a dry location for about 8 months. The bags are not hard but do have some lumps. Can I beak up the lumps and still use them?

Thanks in advance for your help.

Satflier

Read the Ditra installation Handbook (schluter.com) and follow their instructions to the letter. in your situation I think they call for standard, not modified thinset to put the Ditra down.

Your relief cuts can be filled with regular caulking or backer rod prior to installing ditra. If you fill them in with thinset they might as well not be there. IMO the cuts were not really necessary with Ditra on top.

wipe a piece of the concrete with water. If the water is absorbed quickly then you are OK. If the water beads on top for several minutes then you should scarify it.

if the lumps break up on their own during mixing you are ok. If they do not, you can sift them out with a 1/8" screen prior to mixing.

With 20" tiles make sure your floor is dead flat before you start. Any dips or humps greater than 1/8" over 6 feet should be leveled.

Thanks Pistolpete for your help.

I tried the water on the concrete and the water does get absorded quickly. If the tension cracks were not needed then I think i'll go with the thinset. The floor should have done all the cracking its going to do as it has cured for a year now with a woodstove heat source.

In my original post I said I had the servoflex for the Ditra (oops) but that is for the tile. Is it appropriate? My tile store recommended it for the tile and Supertec One Step for laying the Ditra. Other than voiding the warranty (what does a warranty truely give you anyways) will this be okay for laying the Ditra down? Kiesel's website says it is modified but I am unsure of the consequenses if there are any. I am also unsure if they will take it back after 8 months!

I do not have the kitchen cabinets installed yet. Should they be installed and tiled up to or should I do the tile job first, covering the whole floor and then install them on top of the tile.

Thanks,

Satflier

Kiesel is a modified mortar but can be used between the ditra and the tile. If I understood it correctly it won't void any warranty either.

Super-Tek One Step will work fine for the Ditra installation over concrete. Just remember the consistency of the mortar should be wetter or looser than a normal tile installation mix.

The Kiesel Trio-SuperTec will work fine for the tile installation over the Ditra, even tho its a modified thinset. It's a self curing mortar that is fully load bearing (cured) after 3 days.

With regards to Schluter's warranty, they still do not provide a written warranty for anything other than an unmodified thinset used to install tile over Ditra. Any other product used would be up to the discretion of Schluter.
I would not be concerned using the Kiesel Trio over Ditra. I've been using it since it was brought into Canada. Excellent products!

I would install all the floor tile prior to any cabinet installations if that option is open for you.

Randall.

You and Kman helped me last year with a bathroom floor that came out beautiful when it was done. Being new to this I sweated (mentally and pysically) right to the last tile. I will let you know how the kit/dining rm goes then onto the tub surround and tile shower.

Many thanks for your help.

Satflier

People often try to save a few dollars by leaving out the tile under the cabinets. If you think you may be short on tile, then this is an option. The disadvantage with not going wall to wall is the next time you renovate and want to put the stove or fridge in a different spot. matching tile will not be available.

I occasionally leave out a foot and a half under the cabinets and put in a few scraps along the wall for the cabinets to sit on. But this always at the custmer's request, not my preference.