Floor Area Ratio


Are basement levels included in FAR calculations? Does it depend on the City the building with basement(s) is located in?

Hi @ngolban - it depends! Each jurisdiction can set their own rules about what does and does not contribute to FAR. In NYC for example, a basement (which is defined as a story with more than half of its height above the grade plane) does count as FAR, but a cellar (which is the opposite; more than half of its height below the grade plane) does not.

On the ARE, a question (or case study) should provide clear instructions - these are typically found in the definition section of a zoning ordinance, where ‘floor area’ will be defined.

Looks like Chris already got you a great answer! If you’d like an example of what that looks like in a specific AHJ, this is how it’s calculated in Portland, Oregon: https://www.portland.gov/bds/zoning-land-use/residential-infill-project/understanding-floor-area

Ope sorry Kate - I got excited to answer about one of my favorite topics and didn’t realize that @ngolban had tagged you.

Thanks for sharing the Portland definition for floor area - it has some similarities with NYC, specifically about lower levels counting (or not) towards floor area. I really like their diagrams as well!

If anyone is curious, you can find NYC’s longggg definition of floor area here:

Thank you both! Hoping that if this comes up in the exam they clearly specify whether the basement is included or not.