Covered outdoor screed

Hi,
I have the following questions.
I am planning to renew the tiles in front of my door in the covered outdoor area.
However, when removing them, I noticed that the screed layer under the old tiles is in very poor condition.
The screed thickness is about 9 cm.

I would now like to remove the screed and pour a new one.
Do I have to use an edge insulation strip and PE foil here? At the moment, a bonded screed is installed. Since the area is very small, I am leaning towards a bonded screed again. Or is it done today as mentioned above, as a floating screed? I am attaching a picture of the entrance area.
Thank you very much

Hello questioner. What you consider a "very bad condition" of course cannot be assessed by me from a distance. However, the area shown in the photo is "manageable in size" (or small), so dismantling the screed podium cannot be a big mistake with uncontrollable large expenses. Since the podium is not subject to impact sound or thermal insulation requirements, a composite construction with (or under) the new screed is the right decision. Edge insulation strips are not required in this situation! With 90mm screed, however, I would apply it in two layers, since continuous good compaction during application is almost impossible at this thickness. Use a cementitious bonding slurry between the screed layers! Apply the second screed layer the next day (since the small area does not need to be walked on) or later. However, if the first layer should remain exposed for several weeks, it would be advisable to pre-wet the existing screed surface before applying the bonding bridge. This avoids inevitable drying cracks later in the upper layer. Good luck: KlaRa

Thank you for your reply.

I would like to use fast screed. Would you also work in 2 layers here or would you advise against fast screed?
Is a bonding slurry layer also applied under the first screed layer?

One more thing:
Would you include a probation [Bewährung] as well?

@ "Immo2014": The use of a rapid-setting cement has nothing to do with the compaction of a screed structure with planned larger cross-section thicknesses. It either sets faster (usual definition) or due to its material properties achieves readiness for covering faster (nonsensical, as it is intended for outdoor use). A two-layer structure should definitely be applied. With the bonding bridge, as described by me. Reinforcement, insofar as this term is even justified in screed technology, is not necessary, as it is only mentioned in DIN 18352 "Tiling and slab work" (does not mean: recommended). Such an AKS mesh fabric, also called "anxiety iron" in practice, was removed from DIN 18365 many years ago. Because the use of such a mesh rather promoted damage due to an unintended separation layer and made no sense from a building physics point of view anyway due to its position in the lower screed edge zone. (That is why spacers are also used in concrete construction so that the "real," twisted reinforcing steel does not just lie on the sub-base like after a metal burial, without effectively supporting the tensile zone of the concrete structure.) That means: DO NOT incorporate mesh fabric as reinforcement into a screed mortar (the term reinforcement, on the other hand, is generally part of the German Criminal Code in connection with the legal consequences of a criminal offense)!! -------------------- Regards and good luck: KlaRa