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How to Dimension a Floor Plan

Elizabeth Abbey

As computers continue to advance architecture, dimensioning has become easier. Sketches or paper drawings are still used, and accurate dimensions are always important. Using either method, you should know standards to lay out dimension lines and make them readable for the people who will eventually need them to build the structure.

Step 1

Assuming that the floor plan is made and drawn to scale, determine whether you will be dimensioning with a computer program, such as CAD, or paper. The difference is the time it will take to determine the length or width of objects in the plan, which takes less time with a computer. If you are using paper, you will need a scaled architectural ruler to measure each line you’d like to dimension on the floor plan.

Step 2

In CAD, you will need to set your preferences for the dimensioning tool. Decide whether you want to measure to the nearest 1/4 inch or 1/8 inch, and make it consistent throughout the floor plan. The key is to have all dimensions be consistent so they can be understood by whoever is doing the construction. Once decided, save it so it will automatically apply to your templates.

Step 3

Ordering how you dimension is an important step in how contractors and others read the plan. Dimensioning elements that occur first in buildings, such as columns, foundation walls, etc should come first. If there are repetitive columns that are spaced equally, only one should be labeled with a dimension while the others can denote: "eq" or "same." Use the centerlines of columns or walls as a fixed point from which to measure.

Step 4

Lines are used to mark the boundaries of what you are dimensioning are called strings. In a CAD program to measure using your dimension tool, click at the starting point and again at the end point. This will give an exact calculation. Similarly on paper, place your ruler along the line you wish to measure (make sure your scaling matches) and read the measurement. Draw a line parallel to what you just measured and write down the dimension.

Step 5

Dimension things that matter. Rooms do not always need to be dimensioned and can be notated instead. For example, they can be notated 10 feet x 10 feet. This still gives accurate measurements without clogging up the floor plan.