Understanding the Square Footage of a House

How to quickly and easily calculate how many square feet are in a house. Learn what to count and what not to count and where to measure.

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Square Feet

To solve for area for a rectangle, you simply multiply the width by the length. Sometimes, solving for the square feet in a house is just that simple. Sometimes it’s not.

When a building’s shape consists of multiple sides and offsets, then break it down into multiple rectangles. I helped frame a house once that contained over 50 outside corners. To calculate the square feet for something like this is complicated to say the least. Good thing in our case we had a good set of blueprints that already had it calculated. So if you have blueprints, be sure to check them first.

If the house has more than two basic rectangle, then first make a sketch of the outside perimeter of the house. The scale does not matter, but try to get it pretty close.

Measure each offset and write it down directly on the drawing. Just know that where one rectangle stops, the joining rectangle should start. Sides can not overlap and can not have gaps in between them. If you notice an area of missing space on your sketch, you have to tally up the numbers to see what is unaccounted for. Then add that missing space back in as another rectangle, or in more complicated scenarios, you may have use a collection of rectangles.

Measure from outside of wall to outside of wall. Include the brick or whatever other veneer covers the exterior of the wall. You’re not going to have an accurate calculation if you measure the area of the finished floor.

Don’t forget about subtraction. In a situation where a layout is pretty much a basic rectangle with a little chunk gone, treat it just like that. Calculate the main rectangle’s area and then subtract the void from it. Whichever way has fewer steps is the way to go.

Other Factors

If there is a basement or an upstairs included, then foyers get counted only once but stairways and elevator shafts get counted for each floor. Basement and attic square footage are counted as living square feet as long as they are finished.

Porches, breezeways, garages are square footage, but they are not included with the living area,