The One Weird Trick to Preserve Big Old Houses and Increase Affordable Housing

Mark Fruin

The Chicago zoning code has a number of restrictive rules designed to prevent the less affluent from living near the wealthy. The most insidious is the minimum lot area (MLA) per unit. This is what prevents a structure in Single Family Zones (RS-1 to 3) from allowing multiple families to share the lot.

The minimum lot area per unit for RS-3 zoning is 2,500 square feet per unit. The standard Chicago lot size is 3,125, so only one unit is allowed in the standard Chicago lot. Defenders of single family zoning will say that RS-3 allows for duplexes, however, you would need to have a 5,000 square foot lot to build a 2 flat by right in a RS-3 zone.

I propose is reducing the minimum lot area per unit for older homes to 1000 square feet. This would allow older single family homes that are at risk of demolition to have a 2nd life as a 2 or 3 flat. This isn’t revolutionary and probably won’t have a big impact in some part of the city. However, near L stops, where there is demand for smaller units, this could provide affordable housing and save old homes.

An example of how it would work:

Lets say you are a retiree with an older 2,000 square foot home in a RS-3 zone on the standard Chicago (3000 square foot) lot. That’s a lot of house for one or two people. You might consider selling to a developer that would tear the property down and build a new 3,000 square foot home. But, you like your neighborhood and want to stay. Under the lower the MLA for older homes of 1000 sq ft, the retirees could live on the first floor and convert the 2nd floor to an additional unit. This would provide them with additional income and create some gentle density missing middle housing.

Why this could work:

Some progressive alders in Chicago are afraid of allowing denser development in single family zones because they fear this will accelerate displacement. I don’t believe that is the case, but this piece isn’t the place to rehash that argument. The beauty of applying this rule to older homes is that it doesn’t risk increasing displacement or demolitions. Instead of destroying older housing stock that provides naturally occurring affordable housing, this makes older homes less likely to be demolished as now they can be used for dense housing.

Another reason it could work is that it’s conceptually very similar the the ADU pilot that just passed. This is specific to older homes, but is similar in that it relaxes classist zoning rules to create affordable housing.

The Carrot and the Stick:

Recently the city imposed a new ordinance to prevent demolitions near the 606. It is a $15,000 fee for single family homes and a $5000 per unit for multi unit buildings. This fee is a good tool to help prevent demolitions, but I could call this the stick. The fees shift the incentives to make it more appealing to preserve old homes. The idea of reducing minimum lot area per unit works in conjunction with the demo fee to further shift incentives toward preservation of homes and density.

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