Garage floor tiles or 2K coating

Hello everyone,

I am completely new here and looking for help / your opinions on a problem that has arisen in my garage. I hope it’s okay that I’m joining this thread?!

A bit of background:
We built 6 years ago. Did quite a lot of it ourselves. Most of it worked out pretty well. However, not everything. I have massive problems with the garage floor and apparently did everything wrong from the very beginning... Now it’s no use to say “you should have rather…” anymore... (please don’t stone me – now comes the unvarnished truth – I will pay my learning fees now )

Construction of the garage floor:
The floor slab was poured directly with the ground floor slab of the house.
Thin construction foil
Flowing screed (laid in one go with the screed in the house)
Primed
Tile adhesive
Porcelain stoneware

And at some point, it was time: real living room feeling (see first picture – this is only the front half of the garage. Total size: 4x9 meters)

For a few years, everything was great.

Then the first tiles started to loosen in the front area of the garage.

Removed a loose tile once. Then the shock: tile adhesive completely decomposed and even the surface of the screed can simply be scraped off with a spatula...

Yesterday I removed the floor covering from the front half of the garage again. All tiles could be simply detached. (see 2nd picture)

And now: at a loss.

How can I fix this???

THANK YOU in advance for your valued feedback!!!

Regards
Niko

Was the screed not dry when the tiles were laid? Wrong tile adhesive?

Remove all the tiles and have the garage coated, then you will definitely have peace.

Yes, the screed was dry at the time. It also lasted for several years. Could it be that moisture is rising from below? No car has been in the garage for months. It was very warm and yet everything was damp...???

Your joints have let the salt through and it eventually decomposes everything, including the concrete.

Your joints have let the salt through and that eventually decomposes everything, including the concrete.

That was also my first thought. I just didn't understand why everything is still soaking wet months later...?

I just wonder what I have to do now to avoid the same result in 2-3 years or so.

Tear everything out, put it back in, and then just use "different" joint compound... would that be enough??

Tiling is stupid.