How Are Adjusted Max FAR and Buildable Area Determined?

What is the adjusted maximum FAR?

The adjusted maximum FAR represents the maximum floor area ratio allowed for a lot that is covered by more than one zoning district.

Because each zoning district may allow a different FAR, a lot-level FAR is calculated by multiplying each lot portion with its specific district FAR value and adding them up.

This adjusted maximum FAR is used to determine the total maximum buildable floor area for the entire lot.

How is the adjusted maximum FAR calculated?

For multi-zoned lots, the adjusted maximum FAR is calculated as a weighted average:

SUM(Lot area within zoning district × District Max FAR) / Total lot area = Adjusted Maximum FAR

Where:

• Lot area within zoning district is the portion of the parcel located in that zoning district
• District max FAR is the applicable maximum FAR for that zoning district
• Total lot area is the full lot area across all zoning districts

For example, for a lot covered by three zoning districts with the following area and district FAR breakdown:

The equation for determining the lot’s adjusted maximum FAR is:

(3,504 × 0.75 + 1,250 × 1.00 + 1,058 × 0.75) / 5,812 = 0.8

SUM(Lot area within zoning district × District Max FAR) / Total lot area = Adjusted Maximum FAR[ET1] 

How is the maximum buildable area calculated?

Once the adjusted maximum FAR is determined, the total maximum buildable area for the lot is calculated as:

Total Lot Area × Adjusted Maximum FAR = Total Buildable Area

For example:

5,812 SQ. FT. × 0.8 = 4,650 SQ. FT.

This means the total buildable floor area for the lot cannot exceed 4,650 square feet, even if some lot portion’s zoning allowances appear to permit more buildable area when viewed separately.

How are buildable areas by zoning district calculated?

District-level buildable area calculations help explain how the lot's floor area may be distributed across zoning district portions. So, for multi-zoned lots, property reports also show a zoning district-level buildable area for each portion of the lot.

For each zoning district, the equation uses the greater of:

• the zoning district's own maximum FAR

     or

• the lot's adjusted maximum FAR

As such, the district-level buildable area equation is:

Lot Area within District × MAX(District Max FAR, Adjusted Maximum FAR) = District Buildable Area

However, district-level buildable areas are not always cumulative and the total buildable area across all zoning district portions cannot exceed the lot's overall maximum buildable area. So, for our lot consisting of R2A, R4 and R3A portions, the total buildable area cannot exceed 4,650 square feet.