While the final up-zoning guidelines are not yet available (and indeed are still under discussion) it is important for people to know the facts. The above map is a VERY generic guide to current residential zoning. Below is the actual zoning map which shows a lot more variability throughout the city. Note too that some areas, such as Brattle Street are historically preserved so nothing visible from the street (lawns of facades) can be changed. Below is the actual zoning map.
At present, housing density varies across the city: A-1 (3.6-7.3 units per acre); A-2 (4.8-9.7 units per acre) B (8.7-17.4 units per acre), C (12.1-24.2 units per acre), C-1 (14.5-29.0 units per unit). If the City is planning to increase housing density in A-1 or A-2 districts from 7.3-9.7 units per acre to C or C-1 levels of 24.2-29.0 units per acre, this could bring considerable change to the historic look and feel of most residential neighborhoods . This does not mean that all homes within a district would conform with the new zoning regulations, since existing housing that is not demolished to build larger units would still remain, much as taller and larger housing that were built before zoning was enacted, or prior to a down-zoning also remain.
At the bottom of this post is a detailed map of current zoning areas. For more detail look at the CITY ZONING MAP itself.
For more on Cambridge Housing typologies and their distribution read the 2016 Cambridge Housing Profile
HOW MUCH SINGLE FAMILY HOUSING IS IN EACH CAMBRIDGE DISTRICT NOW?
As a general principle, Cambridge residential district zoning differentials vary by neighborhood as does the percentage of single family homes (SFH) now in these districts.
Generally speaking The A-1, A-2, B, C and C-1 residential areas conform with the percentage of single family homes now in each district. In the map below we can see those differences, while also noting that there is a general trend across the city to add more single family housing (as infill or through conversions of two and three family homes into single family homes. In the map below we can see the percentage change in that direction.
Not surprisingly, housing sales prices differ somewhat by neighborhood and more significantly between 1, 2 and 3 family homes (data 1995-2015)
Single Family, Two Family, and Three Family Housing costs vary as well.
Building permits are relatively evenly divided across the city except in the areas of major commercial development - East Cambridge and Alewife.
Condos are widely distributed across the city.
Significantly, the percentage of Single Family Homes is also widely distributed, ranging from 41-58% (at the highest) to 21-30% SFH at the lower end. And nearly every neighborhood in the city has seen some net increase in the numbers of SFH over the 2000-2010 period - either through infill or through the conversion of two family homes into one family homes. SFH are in great demand and receive the highest prices.
Housing Types are Widely Dispersed Citywide, New Zoning Density Criteria Seem Not to Be Needed
As suggested above, each of the different residential zoning districts currently has different allowable densities (FAR - Floor Area Ratio figure that designate the size of buildings allowed). This is mitigated by allowable height and setback requirements. Equally impactful is the minimal lot area for a dwelling unit (DU - home). This is where green space amounts comes into play and the concerns that in denser areas (B and C areas we can get heat islands due to the lack of shade trees). Neighborhood "look" is often defined by the amount of front yard set back amount required.. Residential heights in A-1 through c-1 remain the same (35 feet) though the average SFH height city wide is 2.5 stories (or 35 feet). OS (Open Space) refers to the Min. OS Ratio = minimum required ratio of usable open space on a parcel (not including parking) to total land area, expressed as a percentage. This Minimal Open Space (preferably Green Space) requirement like set backs is critical to questions around heat island impacts, tree shade, on site play areas, out door patios and other issues. This, along with the Min. Lot Area, also determines in part the distance from one person's home from their neighbors. Cambridge as one of the most dense cities in the country (4th -5th most dense city in the country with a population over 100,000) has many homes which are tightly positioned both on the property and in relationship to each other. Moreover in Cambridge it is the reality that the land on which one's home sits is more valuable than the home itself.
The Graph Below Provides a more Detailed Look
Where is the Greatest Need/Demand for New Rental Units?
The greatest City demand for rental units remains the main transit hubs - and these units are at a premium. These are also the principle areas of the city considered to have ready access to Public Transport. This is where the Envision Report suggests that greater dousing density might be made available.
THE CURRENT CAMBRIDGE CITY ZONING MAP
Below is the map of the current Cambridge city residential zoning districts. A detailed version can be found at:
CITY ZONING MAP
Below is a map prepared by CDD for their January 2022 Planning Board presentation to simply the zoning district residential codes, but as one can tell by comparing these two maps, the variables within each district often are considerable. What also is clear from the map below is how much of our city is now subsumed by large commercial developments and institutions (Harvard and MIT most importantly). We have altered the colors for each district to make the map appear less politically charged.