Good question. IANAL, but i would imagine the floor plan is public record. If, someone were to build a new building using a previous designed floor plan, I can see how that could be an issue. But that's not even whats going on here. they aren't using the ACTUAL plans that the architect drafted - they're making their own map, which is akin to taking photos of the space. Like how record companies can own a recording but not a song. Where you get it from matters.

But, not a lawyer. Curious what others make of it.

A floorplan is just a diagram showing factual data about a house, facts can't be copyright.

If you copy the architects drawings to make the floorplan then copyright may apply, however.

If the floorplan itself had intrinsic worth as a substantial piece of creative art, then maybe, just maybe you'd have a case. But the defence of "i measured the walls in my house and drew a plan" (using a computer, for example) should be watertight.

I would assume so, but iRobot will not be copying the original floor plans, so that is not relevant. iRobot will be creating their own floor plans based on their own measurements acquired from customers' Roombas.