Foundation for a 3x3m pergola

Hello,

I am a bit uncertain about the foundation for a 3x3m pergola. We have a terrace with floating but very well secured concrete slabs (about 4 cm). Now, aside from all recommendations, would you necessarily build a foundation 30cmx30x40cm there, or should the pergola hold on the slabs as well? Alternatively, we are considering removing the affected slabs, removing the gravel layer, pouring 10-15 cm of cement mortar, laying the slabs into the mortar bed, and then anchoring the pergola into the slab. The pergola is generally quite well protected from the wind, located close to the house. The pergola will be made of powder-coated aluminum, so quite heavy.

Thanks for your tips and best regards

Is it really a pergola, so without a roof, basically just rafters? Then I would probably do it that way too. If a roof is planned in the medium term, I would already make proper foundations but 80 deep.

Whether 80 cm of foundation is necessary can be debated, but the 10-15 cm as a base layer are definitely not enough. The dowels should then go through the slab into the foundation.

Is it really a pergola, so without a roof, basically just rafters? Then I would probably do it that way too. If a roof is planned in the medium term, I would already make proper foundations but 80 deep.

Ah, I forgot to mention. It will have a louvered roof.

Then make a proper pad foundation

Yes, with a roof proper foundations. The suction forces that pull during a small storm are incredible. Axel at the beginning of the year tore down our pavilion and only had gusts up to 79 km/h. That is actually nothing.