Back to bed height and comfort. I am building a folding bed that becomes a seat. Wanting to keep the windows open for my view and limited by wheel wells, and not a high top. I decided on 12 inch high frame, from the floor. A few inches of foam upholstery will add a bit to that. It is a compromise between head/ceiling and knee/fold when sitting. This is my 6th build and I try to learn from the past.