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One of the metrics I have been using to estimate the impact of zoning changes for residential neighborhoods is "zoned capacity": to what extent does a zoning amendment create new capacity for housing units?
For example, simply eliminating explicit single family and two family zoning restrictions would increase zoned capacity in these neighboorhoods by 2359 units. Many of these units *already exist*--e.g. there are hundreds of triple deckers in B zones--but they would be conforming.
Specifically, such a change would reduce the number of non-conforming residential properties based on unit count by 1.7%, citywide. It would legalized properties like this three-unit home which is currently non-conforming, built in 1867.
It also establishes that some changes which seem like they would be effective create very little new housing on their own. For example, if you were to double FAR maximums in all residential districts citywide, it would only add capacity for ~400 total units due to other limits.
Similarly, if you leave FAR the same, while lowering all lot size/unit minimums, you don't generate much in the way of new zoned capacity: about a 10% increase in total zoned capacity would become available.
On the other hand, changing our most restrictive areas of housing--the A-1 / A-2 single family zones--from their current zoning, designed to keep out the "concentration of negroes" which "threaten to spread" can offer significant new zoned capacity.
Simply updating the A-1/A-2 zoning to match the B zoning restrictions -- lowering lot size/unit minimums, and allowing two-family development -- would increase zoned capacity *citywide* in residential zones by around 10%.
But there's no reason to be so conservative. Such a change would *still* leave 42% of the city as it is built today as non-conforming based on unit count alone: that is, this comes nowhere near to allowing for the type of city *we already have*.
This is because most of the city was built before the *current* restrictions, which were introduced in the 1940s and 1960s, locking the city in place by making most of it illegal to replace.
During the most recent City Council campaign, @ABetterCambMA asked candidates for City Council: "Would you support abolishing these restrictions by establishing citywide minimum zoning that allows more multifamily housing?"
Every elected candidate except @DennisCarlone said yes.
Every elected candidate except @DennisCarlone said yes.
Why do Councillors want to do this? The reasons are varied, but across the board, support ending exclusionary apartment bans: they recognize the racist history that survives in our *current* zoning map, and the need to bring an end to that harm today.
Councilor @qzondervan said: "single-family zoning [was a] racially exclusive practice that denied homeownership opportunities to black families starting during the New Deal under FDR, which has led to the generational wealth discrepancy between black and white families."
Councilor @VoteJivan "Like most Cambridge residents, I live in a beautiful triple-decker building and couldn’t afford to live in anything other than an apartment ... But there are large parts of Cambridge where it’s illegal to build my home."
Councilor @Marc_C_McGovern explained: "we are responsible for dismantling [racist zoning] in the present. There are sections of Cambridge that are completely off-limits to low and moderate income people. We need to take steps to change that."
Mayor @MayorSiddiqui added: "Previous zoning laws prohibited multi-unit construction in sixty percent of neighborhoods, leaving the city with limited options to address the housing shortage and build additional housing for low and mid-income residents."
So, let's look at what that means, in practice: how can we legalize the city we already have, while tearing down the walls we've used to "protect" neighborhoods from supporting lower income families for the past 100 years?
The standard sized Cambridge lot, as the city was originally divided is a 50'x100' plot: 5000 square feet. If we want to legalize triple deckers citywide, then it should be legal to construct a triple decker on a standard sized Cambridge lot.
Looking at our existing zoning definitions, it's clear that we can't simply upgrade the City to A, B, or C zoning and achieve this: the lot size/unit minimums would prevent us from building a triple decker on a standard lot under any of them.
Okay, so let's look at C-1:
- .75 FAR on a 5000 sqft lot is 3750 sqft, enough to build a triple decker.
- 1500 sqft lot size/unit minimum means we can build 3 lots on a 5000 square foot lot.
- .75 FAR on a 5000 sqft lot is 3750 sqft, enough to build a triple decker.
- 1500 sqft lot size/unit minimum means we can build 3 lots on a 5000 square foot lot.
This is a decent start under a change like this, an estimate suggests that it would legalize about 1/3rd of our current illegal buildings: "The number of non-conforming properties (as currently built) would be approximately ~30.8%, compared to 43.5% under current zoning."
But the reality is that even under these conditions, many triple deckers in Cambridge would still be non-conforming, because their lots have been subdivided since the original platting of the city, leaving many triple deckers on smaller lots than 5000 square feet.
The median lot size of a triple decker home in Cambridge is 3410 square feet. If we refer back to our earlier table, we can see that existing zoning would allow a triple decker at that lot size if the zoning was C-1A or higher.
With C-1A zoning, a 3000 square foot lot -- like 12 Merrill Street and 9 Newton Street above--could have a triple decker. (45 Locke Street is still too small, and would continue to be a non-conforming triple decker.)
With the limit set at C-1A, we do much better: "The number of non-conforming properties (as currently built) would be approximately ~16.0%, compared to 43.5% under current zoning." We're getting closer to legalizing the city we already have.
Now, this doesn't legalize everything. East Cambridge especially tends to have particularly small and dense lots, and is already zoned mostly C-1 (again: historical inequality is baked right into the zoning). Dense rowhouses aren't really accounted for in this zoning.
And of course, we have actual apartment buildings throughout the city (including in our historically single family A-1 zones!) that would exceed these limits.
But this type of change would be significantly increasing the zoned capacity of the city, bringing it closer to where we were when Cambridge was a genuinely growing city in the early-to-mid 1900s: a 100% increase in zoned capacity.
It would legalize 2/3rds of the residential areas of the city that currently aren't legal. It would allow triple deckers to be created on the median sized lot that holds a triple decker today.
This type of change would be a meaningful step towards correcting for systemic inequities that exist *today* in our zoning code; could allow for genuine creation of new, more affordable housing by individuals, not just mega-corporations.
And most importantly to me, personally: It would be taking a step towards saying that the type of city that we already have is one we like, not one we'd like to prevent.
Today, 85% of the city is illegal to recreate in one way or another.
I think we should change that.
Today, 85% of the city is illegal to recreate in one way or another.
I think we should change that.
By the way, if you want to play with this yourself, you can experiment with various configurations at:
https://crschmidt.net/housing/units
e.g.:
Min C-1A zoning: https://crschmidt.net/housing/units?minzone=C-1A
Eliminate SF/2F zoning: https://crschmidt.net/housing/units?singlefamily=a&twofamily=b
2x FAR, no lot min: https://crschmidt.net/housing/units?far_factor=2.0&lot=eliminate
https://crschmidt.net/housing/units
e.g.:
Min C-1A zoning: https://crschmidt.net/housing/units?minzone=C-1A
Eliminate SF/2F zoning: https://crschmidt.net/housing/units?singlefamily=a&twofamily=b
2x FAR, no lot min: https://crschmidt.net/housing/units?far_factor=2.0&lot=eliminate
