Why are stairs counted twice on square footage?

Why Are Stairs Counted Twice in Square Footage Calculations?

The practice of seemingly counting stairs twice in square footage calculations might appear counterintuitive at first. However, it’s a logical approach that stems from the way square footage is defined and measured in relation to different levels of a home.

Brief Summary

Stairs are “counted twice” because they are considered part of the finished living area on both the floor they originate from and the floor they lead to. This is due to the fact that they occupy physical space on both levels and are essential for accessing the upper floor. The area of the staircase opening on the upper floor and the physical structure of the stairs on the lower floor are both included in the square footage calculations of their respective levels.

Expanded Answer

Understanding the Logic

• Functional Space: Staircases are not merely transitional elements; they are functional spaces that facilitate movement within the home. They occupy floor space on both the lower and upper levels, hence their inclusion in the square footage of both floors.
• “From Which They Descend”: The common practice, as outlined in the ANSI (American National Standards Institute) standard for measuring single-family homes, is to include the area of the stairs in the square footage of the floor “from which they descend.” This means the physical staircase structure is counted on the lower level, while the opening for the stairs is counted on the upper level.
• Openings and Landings: The opening in the upper floor, created to accommodate the staircase, is considered usable floor space on that level. Similarly, any landings within the staircase also contribute to the square footage of the floor they are on.

Examples

• Two-Story Home: In a typical two-story house, the staircase leading from the first floor to the second floor would be counted twice. The physical stairs would be part of the first-floor square footage, while the opening for the stairs would be included in the second-floor square footage.
• Basement Stairs: Stairs leading to a finished basement are typically counted in the main floor’s square footage. However, if the basement is unfinished, the stairs might be included in the main floor’s square footage regardless, depending on local building codes and appraisal practices.

Exceptions and Variations

• Local Building Codes: While the ANSI standard provides a general guideline, local building codes and appraisal practices can vary. It’s always advisable to check with local authorities or a qualified appraiser for specific rules in your area.
• Unconventional Stair Designs: Unique or complex staircase designs, such as spiral staircases or those with open risers, might have slightly different measurement rules.

Remodeling Considerations

• Altering Staircases: If you are remodeling and plan to alter the staircase, it’s essential to consider how these changes might impact the square footage of your home. Expanding or adding a landing could increase the square footage, while removing or reducing the size of the staircase might decrease it.

Conclusion

While it may seem like stairs are counted twice, it’s important to understand that they are considered part of the usable living space on both the floor they originate from and the floor they lead to. This practice ensures a more accurate representation of a home’s total finished living area.