We have two engineered foundation options in the US.
A standard crawl space design is included with our plan sets. This is with four perimeter walls and center support for the floor load.  This is designed for a flat plot of land.  For a Trio, the foundation is typically an 8” foundation wall with #4 rebar on 12” vertical centers and 12” horizontals (single mat).  The footings are typically 36” wide and 12” deep on the two sidewalls and 24” wide on the gable walls.
A basement option that can be added to your plans ($1,500) which can work on a sloped lot. This includes a custom floor plan based on how you plan to use the basement space.
Due to the way our structural truss is engineered, a slab foundation is not feasible with the AvrameUSA system.  Other custom options are possible, such as a pier and beam system, but would require custom engineering and soil samples ($1,500-$3,000).