Maximum Office Floor Area on Commercial Sites

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The presence of critical areas on or adjacent to a site affects the site’s maximum office floor area (Land Use Code [LUC] 20.25H.045B). Accurately calculating your site’s maximum floor area before designing your project will save you time and money and result in a faster permit review process.

Critical areas are afforded special protection because of the functions they provide, such as wetlands or because of the risk they pose to life, property, or infrastructure if they are developed, such as steep slopes.

If critical areas are present on or adjacent to a site, the portion of the site that can be developed is reduced to protect the critical area functions. For office developments, the maximum floor area that can be developed on the site is also reduced.

Regulating development density in this way helps protect critical area functions like stormwater detention, water quality improvement, and wildlife habitat. It also focuses development in areas that pose less risk of flooding, landslides, and erosion.

Site Factors

Start by determining the following factors about your site. These factors are used in the equation.

CA represents the total area of critical areas and critical area buffers on the site (in square feet).

BA represents the site’s buildable area, which is the area of the site (in square feet) minus the site’s CA (defined above): site area – CA.

DF represents the site’s development factor, which is the BA divided by the area of the site (in square feet): BA ÷ site area.


Once you’ve determined the site factors above, enter them into the following equation.

(0.5 × BA) + (0.5 × CA × DF) = maximum office floor area


Site Factors

CA = 46,174 square feet

BA = 73,616 square feet – 46,174 square feet

= 27,442 square feet

DF = 27,442 square feet ÷ 73,616 square feet

= 0.37



(0.5 × BA) + (0.5 × CA × DF)

= (0.5 × 27,442) + (0.5 × 46,174 × 0.37)

= 13,721 + 8,542

= 22,263 square feet maximum office floor area