Context: this is a proposal from Google based on our review of the draft (i.e. Pending) definitions for /FloorPlan and nearby terms.
This proposal adds a /layoutImage to /FloorPlan as specified earlier in #2373
Noting that FloorPlan is place-related but an /Intangible rather than a /Place subtype (and therefore not currently supporting /photo) we propose adding a dedicated property more specific than /image to capture FloorPlan-specific imagery. This is a little unusual in that we don't expect schema.org needs properties for all the infinite range of things that can be depicted online; however the type FloorPlan itself is inherently image-oriented and it seems valuable to distinguish floorplan imagery from other images of rooms and apartments.
/layoutImage "A schematic image showing the floorplan layout."
I should have mentioned this comes partly as usability feedback, in that the type FloorPlan almost sounds like an image type, and yet we only have vague language ("The visual/spatial aspects of a floor plan (i.e. room layout, see wikipedia) can be indicated using image.") on how to actually find the plan imagery. This would be amended to reference /layoutImage instead of /image.