Apologize if this had been discussed before.
This is a quote from the US version of the Ditra installation handbook. Are your installation instructions the same? I have heard that in Europe use of polymer modified thinsets to bond tile to Ditra is approved.
I know from experience that a quality unmodified does provide a good bond, but at times I would prefer using a modified thinset. Schluter does allow rapid setting modified to be used but I prefer normal setting material for most jobs. Maybe you have different products available than we do?

Originally Posted by Schluter USA Ditra Handbook

"QUESTION Can ceramic tile, including porcelain tile, be set on Schluter®
-DITRA with unmodified thin-set mortar? ANSWER YES. In fact, we recommend it. Here's why:
Portland cement-based unmodified thin-set mortars are dependent on the presence of moisture for hydration in order to gain strength. Since Schluter®-DITRA is impervious, it does not deprive the mortar of its moisture. This allows the cement to properly hydrate, resulting in a strong, dense bond coat. In fact, after the mortar has reached final set (usually within 24 hours), unmodified thin-set mortars achieve higher strengths when cured in continually moist conditions.
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."

Hi Isaac..

I had this conversation with JB and CX.. and they still wouldn't have it we have different techinque for installing porcelain on Ditra..

Immediately after the Schlüter-DITRA matting is installed, the tiles can be set using the thin-bed method and using a bonding tile adhesive that matches the requirements of the covering. It is recommeded to fill the square cavities with the smooth side of the trowel and to establish a regular pattern in the bonding adhesive with the notched side of the trowel in one application. The tiles are fully embedded in the adhesive. Fully embedded installation of tiles in accordance with the applicable professional standards is particularly important for coverings with high traffic loads and in outdoor areas. The notches of the trowel must match the thickness of the tiles. Please observe the open time of the adhesive. The adhesive bed over Schlüter-DITRA should not exceed 10 mm.

I do have an email somewhere that says from schulter to use an adhesive that suits the substrate and tile,, i.e.... flexi on timber floors etc.. so it can be used with porcs..

In US they also do require a flex to attach ditra to plywood, require non modified to bond ditra to concrete. Curious more about what mortars you use to lay porcelain over ditra?

I'd use a spf, no less

spf for me as well

me too spf on all my work homz even concrete

Well I guess I am just
Interesting that the same product would have different installation instructions. In US if you use a polymer modified to set tile to Ditra you void Schluter's warranty.
Plenty of guys here do use polymer modified over Ditra with success, guess you just need to allow extra curing time before traffic or grouting.
Thanks for the info.