Terrace slabs with pedestals on FPO membrane

Hello everyone,

we have several balconies with FPO membranes.

Structure:
200mm concrete slab
120mm PU insulation - WLS023, 120kpa
EPS slope boards - WLS035 150kpa
Separation layer (polyester fleece)
FPO membrane

I am currently considering which flooring I could use here. At the moment, I am leaning towards terrace slabs or WPC decking boards. Both options would be installed with pedestals.

My question about the terrace slabs:

1. These often have a thickness of 2cm. Sizes are 60x60, 80x80, 60x40, or 120x60. Don’t such "thinner slabs" tend to break if they are hollow underneath due to the pedestals?

2. Wouldn’t the floor feel spongy because of the insulation and feel strange with terrace tiles? Does anyone have experience with this? I think it would be less noticeable with WPC decking boards.

No one has experience with insulated balconies and stilt bearings?

It depends on how much build-up height is still available. Vapor barrier + sealing + 12cm + at least 2cm or rather 4cm because water should be directed away from the house.

In recent years, no pedestal supports have been seen in new construction.

Mostly an aluminum rail system.

The floor covering does not feel spongy when walked on; the protective mat is barely noticeable.

I would prefer 60x60x2cm slabs.

If laid cleverly, they won’t slip when exiting.

Joint crosses 5mm absolutely necessary (I don’t know what they are called now but have a slab underneath) so they don’t push up during movement.

It depends on how much installation height is still available.

I would have to measure it. But I could raise the floor covering by at least 10 cm. Maybe even more.

Usually an aluminum rail system

I would have to keep searching. There are a few rail systems on Google, but it doesn’t seem to be very common.