Is terrace slab thickness under 2 cm also okay?

Well, I could get the '81s for about €20 per square meter, so in terms of price, it would already be Dacia. ;)

Concrete slabs? That was my first thought. Like the classic 30x30 or 40x40, you mean? The neighbor gave me a tip (he has porcelain stoneware himself) not to use concrete. When grilling, ketchup or something might spill and cause stains that soak into the concrete. With porcelain stoneware, you just wipe it off and that's it. I just wouldn't like it if it looked stained someday. Hence the switch to porcelain stoneware.

We will also use porcelain stoneware and initially wanted a large format (80x80 or 90x90). But due to objections from the landscape gardener regarding the thickness, we switched to a smaller format. 80x80 slabs with 3cm thickness easily cost >80€ per sqm and that is just too much for us. There are also quite small formats with 3cm thickness (porcelain stoneware).

When grilling, ketchup or something sometimes falls down, makes stains and they soak into the concrete. With porcelain stoneware, just wipe it away and you’re done.

Well... I think there is a counter-argument for every pro... For example, I have experienced that slabs laid in gravel, despite proper compaction, eventually sank. Therefore, this might not be a good idea either. I have grilled on concrete slabs for decades but I’m not aware of that being a problem. But if it’s important to you, then so be it. The next person will tell you that you’re more likely to slip on porcelain stoneware... which is also true, and if fat from grilling gets on it, even more so. Wherever there is a pro, there is also a con or a horror scenario opposing it. Personally, I like sandblasted surfaces quite a bit.

Yes, I agree with you. One says it this way, the other that way.

I wouldn't have thought that it is such a difficult decision, or rather, how do you do it right.

So I would definitely not lay concrete tiles because of stains and everything. My 60x60 in 2cm are so easy to maintain, I am really impressed by them. My brother took them in 90x90, unfortunately they were not available back then. Cost 34€ per sqm... I wouldn't freak out about these 3mm.

Small animal bedding. You can then sweep it up together and dispose of it. : I am actually surprised that as a wood floor enthusiast you don’t want that on the terrace as well.