ᐅ Concrete slab foundation specification for passive house

Hello, I bought a Passive House kit in timber frame construction. Now I want to order the foundation slab. The plot is level, with about 60cm (24 inches) of topsoil, underneath clay. The size of the slab is approximately 60m² (645 square feet), about 20cm (8 inches) thick on crushed glass, with 80mm (3 inches) rigid foam as lost formwork.
How should the specification text including earthworks be formulated?

It is best to first commission a geotechnical survey and then proceed with the tendering based on the recommendations provided there.

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