From the nearest corner, measure the distance to the door opening and note this on your drawing. Ignore casings or trim. Measure the width of the door. Note the direction that the door swings and show this on your drawing with an arc. Now measure the width of the casings around the door and note those on your drawing.
Measure windows from frame edge to frame edge, without the casings or trim. Depending on the purpose of your floor plan drawing, you may want to also measure the height of windows and their distances from the floor and ceiling.
Rather than trying to write all of these on your diagram, use the back of the page as a door/window schedule. Letter or number doors and windows on your plan, then note the various dimensions and notes on your schedule.
Fireplaces, cabinets, built-in bookshelves, and any other features should be measured and added to the plan next. If your plan includes multiple rooms, make sure to account for the interior and exterior walls. Typical residential construction uses 6" exterior and 4" interior walls.
It's also a good idea to measure and locate electrical switches and outlets, thermostats, circuit boxes, radiators, heating and air conditioning registers, and any other elements on your diagram.
A floor plan is an overhead view of a space. An elevation is a ground-level view of a wall. If you need elevation drawings, you'll want to do these on separate sheets of paper. Measure each wall from floor to ceiling, and use the wall-to-wall measurements you already have. Draw the perimeter of the wall. Label it so you'll know which wall is which: e.g., Kitchen: North Elevation."
Draw in all of the doors, windows, cabinets, switches, etc. on each wall elevation.
Once you have all of your measurements and have made a rough sketch of your floor plan on paper, it's time to create your scale drawing using SmartDraw. See how to draw a floor plan with SmartDraw.