A floor plan is a scaled diagram that shows the arrangement of rooms and spaces on one level of a building. It is drawn as if you cut the building horizontally at about waist height and looked down. Walls, doors, windows, stairs, and fixtures are all shown.

Floor plans are the most common architectural drawing. They are used by everyone: clients, contractors, inspectors, and real estate agents. A good floor plan communicates how a space works — how you move through it, how rooms relate, where light comes from.

Scale matters. A residential floor plan is often drawn at 1/4 inch equals 1 foot. A large commercial plan may be 1/8 inch equals 1 foot. Details are drawn at larger scales. The scale tells you how much the drawing has been reduced from real size.

Floor plans are not just technical. They are also social documents. They reveal how a culture thinks about privacy, family, work, and hospitality. Compare a Victorian house plan to a modern open-plan apartment and you see two different ways of living.