Richard_Morrison

This is just a suggestion based on decades of experience. If you are working with a design professional such as an interior designer, you will get far better results in the end if you let them come up with a design(s) and then input their design concepts into your own software to tweak and make it yours. If you go to a designer with your own designs, then you are mostly likely handcuffing the designer and losing a lot of the value of their hard-won experience and training. I have had clients come to me with the rabbit warren that they've designed, and it is very hard to talk them into something better at that point. After all, it's THEIR rabbit warren that they've been slaving over for many months, and they are totally emotionally invested, even if the design isn't very good. I respect the impulse to have control over the design of your own house, but you need to ask whether it's more important to have YOUR design, or a really GOOD (if not GREAT) design. That said, I think the Home Designer tools are great for facilitating communication between a design professional and a homeowner.

Olivier, People are trying to be helpful and the answer is in there, but I would have a hard time following this myself. The terrain is set properly to the main building. (More or less. And you adjust it up and down with the subfloor height relative to terrain.) But you will have to adjust the floor/ceiling/roof absolute levels of the second building to be lower. The terrain doesn't really know how high the buildings are, so you have to set the building heights relative to each other, after calculating how much the flying building needs to drop. The subfloor of the flying building will be changed to a negative number, etc.

To the OP. I don't normally like to get drawn into these amateur vs. architect discussions. DJP is correct that you aren't legally required to use an architect to do the plans. However, taking a quick look at your plan, you might benefit from some limited design guidance from a good licensed architect, even if you don't use him/her to do the condocs. You could probably get a much less awkward plan for the same construction cost by challenging some of your initial assumptions, like stair location. A fresh eye could benefit you enormously if "pride of authorship" is less important than getting a great house.