To draw a floor plan to scale, sketch the room freehand first, measure every wall in one continuous direction around the room, record the openings and obstructions as you go, then transfer the numbers to graph paper at a fixed ratio. The last step is the one that...
To read a house plan, start with the line weights, because the heaviest lines are the walls and everything lighter is either a fixture, something overhead, or a note about the drawing itself. Then find the scale, check the door and window swings, and follow the...