Our customers often ask us this question, so we decided to do an quick analysis on floor plan cost to build based on the number of floors. We analyzed our library of one-story and two-story plans to compare costs and found that two story plans are 14% more affordable to build per square foot on average).
Two-story houses make an efficient use of the foundation, and roof by covering up to twice as much square footage as a one-story home would. The downside is that much of that gain in value is lost because additional unusable floorspace that gets absorbed by staircases.
Here, our methodology is to take the cost / SF or our library of one story and two story houses, while subtracting out the average square footage taken up by the staircase (~85 SF / floor). All data is provided by our proprietary cost to build calculator found here. Note: the same standard material selections and construction variables were held constant across the entire dataset.
As you can see, our two-story home plans are consistently more affordable to build than our one story plans. On average, one-story homes cost $260.21 / SF to build while two-story plans cost $223.94/SF, a savings of about 14% per SF of usable floor area.
Another way of looking at this is: for the same price, you could build a 2,000SF one-story house or a 2,325 two-story house. That's a pretty significant amount of additional floorspace! For this reason, I'd say that two story houses are becoming underrated.
Note that this rule may not always hold. We displayed the data in the chart above to illustrate this fact. In one pairing, the two-story house is actually more expensive per SF than the one-story home. In addition, many of the data points are actually quite close together, meaning that the cost savings may vary depending on the individual layout and design of the floor plan in question. The bottom line is that if you're looking to maximize your budget, then a two-story+ home should be your priority.