A finished third floor in a 1920s or 1930s University Park house makes a lovely guest room: private, quiet, tucked under the roof. Getting anything up there is the difficulty. These staircases are narrow, often turn twice, sometimes have a low ceiling over the last flight, and were built when furniture came apart or came up on a rope through a window.

So we work backwards from the route rather than forwards from the room. We need the narrowest point of the stair, the width at any turn, and the headroom over the top flight, and we compare those against shipping dimensions rather than the finished bed. Freestanding cabinet and chest beds arrive in more sections and are frequently the only thing that can physically make the journey.

The room itself brings the second constraint: sloped ceilings. Under a roof pitch, the usable wall height often falls well short of what a vertical model needs, and the answer is a horizontal fold along the low wall, where a bed only needs about the height of the mattress plus the mechanism. Between the stair and the slope, this is one of the few markets where we sometimes have to say a room genuinely will not take a bed.