This document estimates the Floor Area Ratio of one-, two- and three-family properties in Cambridge Residence Zone B.
Data is from the Cambridge Property Database FY2017.
The actual FAR is computed as Interior_LivingArea / LandArea. Allowed floor area ratio is computed as 0.5 on the first 5000 sq ft of LandArea plus 0.35 for LandArea over 5000 sq ft. Prior to 2002 (approx.) the allowed FAR was simply 0.5 * LandArea. Properties which were in conformance with the old zoning and are now non-conforming are shown as “Prev conforming”.
The first plots show the distribution of floor area ratio in the three property types.
The next plots compare the land area with floor area. 
This table shows the number of conforming and non-conforming properties of each type.
| Property class | Mean FAR | Mean permitted FAR | Conforming | Conforming pct | Prev conforming | Prev conforming pct | Non-conforming | Non-conforming pct | Total |
|---|---|---|---|---|---|---|---|---|---|
| SNGL-FAM-RES | 0.52 | 0.49 | 682 | 49% | 19 | 1% | 689 | 50% | 1390 |
| TWO-FAM-RES | 0.64 | 0.49 | 291 | 25% | 25 | 2% | 843 | 73% | 1159 |
| THREE-FM-RES | 0.85 | 0.49 | 21 | 6% | 10 | 3% | 301 | 91% | 332 |
| Total | 0.61 | 0.49 | 994 | 35% | 54 | 2% | 1833 | 64% | 2881 |
Copyright 2017 Kent S Johnson 
2017-01-27