I have two plans I created for adding onto our 1970's 4-level split. Shown are renderings of the current house, the design with a 13'x10' addition to the front, and the design that builds up. In both remodeling designs, the existing bathrooms, main floor (kitchen/living/dining) and existing staircases remain pretty much as is. In the building out plan, the foundation is extended out 10' forward from the front two bedrooms (one on each floor), for a 260sf gain (130sf x 2) In the building out plan, the footprint is unchanged. The roofs of the center and right sections are replaced, an interior staircase added to access the new over-garage and usable attic spaces. The area gained over the garage is 15'x24', and there is usable space in the attic, at least a nice bedroom's worth. In both cases, the existing siding, roofing material and windows are to be replaced. I am guessing ... totally, completely, guessing, that the costs of the two plans is about the same. Assuming similar fixtures and finishes, does anyone have an opinion about which costs less, or are they really about the same?