When your floor space is cramped, look up. Literally.
This article on houzz describes how architects and interior designers establish a customer’s needs along several axes and can plan small spaces around them, overlapping functions as necessary. Often, the key to meeting every need is vertical space: a lofted bed above a bathroom or living space; storage above doorways and around windows. Just look at this pair of plans for the same space – one taken at an elevation 3 feet above floor level, the other taken 8 feet above floor level.
I’ve discussed the bed as a space-saving opportunity several times before. Sleeping is a horizontal activity, taking up a large footprint but only a couple feet of vertical space. Tiny houses on wheels and small apartments often use a lofted bed configuration. This one-story house goes the other way, placing a bed on the ground level (to stay cool in the summer) under a three-foot ceiling, with a living space above. The Interlocking Puzzle Loft in New York City, pictured at top, takes advantage of space under the bed to enable two levels of living in a volume with only 11-foot ceilings.
Overhead and low-level spaces are also great for storage, and even mechanicals. You can run your kitchen cabinets right to the ceiling, and many cabinet-makers now offer slim toe-kick drawers. You can line your living spaces with upper-level shelves as you’d find on a boat or RV. Instead of a whole room for your utilities, you might consider placing hot water heaters and heat recovery ventilators on floor level, perhaps hidden under a built-in seat. You can even build a secret soaking tub under the floor. Be creative and think in all three dimensions!