The 606 & Pilsen block rules

Why they exist

Two overlays, one worry

Both districts were written with the same purpose in the code: to reduce displacement of low- and moderate-income residents and maintain contextual density of housing typologies that often provide naturally occurring affordable housing §17-7-0592 §17-7-0582. Near the Bloomingdale Trail that meant two-flats being replaced by single houses; in Pilsen it meant the reverse risk on blocks zoned for multi-unit buildings.

So the ordinance does something unusual: instead of setting one rule per district, it makes the block itself the rule. Two lots with identical zoning, one block apart, can have different answers.

The 606

Predominance of the Block

There is an escape hatch, and it is narrow. Where the block test requires a two-flat or a multi-unit building, a detached house may still be established — but only if no such building can be provided under the applicable bulk and density standards, including the reduced 1,500 sq ft per unit §17-7-0593-A. Two units need 3,000 sq ft, which a standard 3,125 sq ft lot has — so the hatch opens mainly on a substandard lot.

The district covers RS-3 and RT-3.5 parcels inside a boundary that runs from Addison and the North Branch across to Pulaski §17-7-0591. The boundary has since been widened to take in parts of Avondale, Hermosa, Humboldt Park, Logan Square and West Town, and the code’s own editor’s note records that the printed map figure was not updated to match — so read the boundary description, not the picture.

Pilsen

Multi-Unit Preservation

Pilsen’s district runs the test in the opposite direction. Inside its boundary, a detached house or two-flat may only be established when more than 50% of the zoning lots on the same block face are already improved with a detached house or a two-flat §17-7-0583. On a block of three-flats and courtyard buildings, the low-density option is simply off the table.

The district is made of RT-4, RM-4.5, RM-5, RM-5.5, RM-6 and RM-6.5 parcels inside a boundary running between 16th Street, Cermak, Western and Wood §17-7-0581; the operative section applies the test in those districts and in B and C districts within the same lines §17-7-0583. As with the 606, unimproved lots may be counted either way, at the applicant’s choice, for this calculation only.

Demolition

The surcharge that comes with them

Both districts carry a demolition permit surcharge, administered by the Department of Housing rather than by zoning: $20,000 per dwelling unit and $60,000 per building on a residential demolition inside the two districts. The 2024 Northwest Side Preservation Ordinance raised it from $5,000 and $15,000 and extended it to December 31, 2029.

It is charged on the permit, so it belongs in the acquisition math for any deal that assumes a teardown: a six-flat is $180,000 before a shovel moves.

Source: City of Chicago, Department of Housing — Demolition Surcharge. Figures current as of September 2026; check the city page before relying on them.

In practice

How to run the test on a real lot

1. Check the district and the boundary. Both have to be true. RS-3 outside the 606 boundary is an ordinary RS-3 lot.
2. Draw the block face. Your side of the street, from one intersecting street to the next. Corner lots and the facing side are out.
3. Count zoning lots, not buildings. The denominator is lots; a double lot with one building is still counted as the code describes it.
4. Classify each one. More than one dwelling unit, or not. Unit counts come from records, not from the number of doorbells — see nonconforming uses for why the record matters.
5. Decide how vacant lots help you. They may be counted either way, so count them the way that supports the project you want.
6. Price the surcharge if the plan involves demolition.

Questions

Common questions

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