Creating walls

Hi. Anyone has created walls in Illustrator to use in floor plans?

I want to create a box with a stroke (wall thickness), but the stroke only provides snap to object in one side.

So, if a going to place furniture inside the box, I want to snap to the inner stroke and when I'm going to place other rooms, for example, I want to snap to the outer side of the stroke. I've tried to change it to path, but when I scale it, it does not keep the original proportions.

Thanks.