Balcony renovation, questions about the substrate for tiles

Tiles can be installed "snugly" against edge profiles, but they should not be. Therefore, it will make sense to leave a 3mm to 5mm wide joint between the tile edge and the profile edge and to fill the joint chamber in the upper third with an elastic sealant. At the door, there is currently a multi-bent profile. A similar one will be used there again. Probably, a new fabrication will be necessary anyway due to the new door. The tiles will also not be laid "snugly" against the door here, which is why a joint (covered by the cover plate) will be created within the new covering before the door transition. My recommendation here is to loosely place an expansion tape parallel to the door entrance before attaching the new cover plate and then press it lightly by means of the cover plate. A suitable expansion tape is, for example, "Hydrotite SS0330" from TPPH (or comparable). Only 3mm wide joints for large-format tiles seem risky to me! I would go for 5mm because the tiles expand somewhat unpleasingly on a balcony during warm seasons. For a tile format of 1.20m length, the substrate must be very even (DIN 18202 Tab. 3 line 4 = increased evenness). Check!! Regarding the primer: I already wrote: synthetic resin (epoxy resin, 2K). Common tile adhesives are mostly cement-based and thus also suitable for outdoor use. Prefer medium-bed, because due to the remaining ribs (and the resulting hollow chambers) beneath the plates, i.e., within the adhesive bed, no frost damage can occur in winter. -------------------------- Logging off: KlaRa