A Carriage House may be either freestanding or attached to a house, and may have a footprint of up to 800 square feet. It may have up to a 2-car garage on first level, with living space primarily on second level, although some living space may occur at ground level. Carriage Houses often appear to be one story when viewed from the eave side, but they tuck a lot of space into the attic over the garage. As a result, the roof slope is usually quite steep in order to fit the space under the roof.
Attic rooms were once very common in more vernacular houses across the country. Recently, most construction has full-height second story walls in part because it’s more convenient for high-volume production builders. As a result, most of the methods for furnishing and using spaces where the ceiling hangs low toward the eaves have been lost. Old houses often had ceilings as low as 30 inches, and the rooms were quite useful... and they can be that way again.