Ipe is usually installed over a wooden base structure, although the structure can be made of metal, plastic, or any other number of materials. Ipe decking or any hardwood or composite decking needs to be on top of joists so that air and water can flow underneath. I am not familiar with this particular deck, but from the photo it looks like the structure is lower than the concrete slab. This was probably done so that the deck is flush with the concrete.

This requires a complex detail to insure that there is enough air flow under the decking so the ipe does not warp. This is why you need to hire a landscape architect.