Cook County staff propose ‘residential open‑space’ overlay to encourage clustered, affordable housing

Cook County land‑use staff presented a draft zoning and subdivision change to create a Residential Open Space Overlay (ROSO) designed to encourage clustered, lower‑cost housing while preserving open space and limiting short‑term rental use. Planner Neva Maxwell described the overlay at the committee meeting and said the measure is intended to be site‑specific and to apply only in selected FAR‑2 and FAR‑3 zone districts — the county’s 10‑ and 5‑acre rural district areas — and outside shoreland.

Maxwell explained that an overlay district “keeps the original zoning” but places an additional layer of rules on top so the county can allow different lot and use rules inside the overlay without altering the base zone. The proposal would permit smaller lots in exchange for dedicating at least 50% of the parent parcel as undeveloped open space. Maxwell said the overlay would also explicitly prohibit short‑term vacation rentals within the ROSO to prevent commercial vacation‑rental pressure in the newly created housing stock.

Under the draft, a developer would seek a rezone to the ROSO, undergo a public hearing and, if the rezone is granted, pursue a preliminary and final open‑space subdivision plat. Maxwell said that lot density inside the overlay could be increased (she is proposing a multiplier, previously 1.5x and being considered up to 2x, to improve economics) but only after the developer completes the required site planning, wetland delineation, septic and shared‑utility designs and homeowners‑association documents for shared infrastructure. Maxwell said the rezone step gives early predictability to developers while the platting and final construction documents are required before lots are sold.

The purpose, Maxwell said, is to "encourage workforce housing in areas where we have existing infrastructure," preserve large tracts as open space, and cluster development so infrastructure costs and environmental impacts are reduced. She used Mink Ranch Road/Woodland Foothills as an on‑the‑ground example of small‑lot clustered development and said clustered design can place wetlands, steep slopes and ledge inside the preserved open space rather than forcing costly per‑lot mitigation.

Commissioners asked about details including whether duplexes or small multi‑unit buildings could be permitted (Maxwell suggested duplexes could be allowed if each unit is on a separate lot and multifamily would be considered via conditional use), whether the overlay would allow home occupations, and how the county would manage potential conflicts with nearby FAR‑1 uses such as kennels. Maxwell stressed the proposal is site‑specific and that the rezone/public‑hearing step allows the county to vet adjacency issues and set conditions.

Planning commission review of the proposal was informational and unanimous; the next step described by Maxwell is additional stakeholder outreach (including the Housing and Redevelopment Authority), refinement of language with the land‑use attorney, public notice and a planning commission public hearing in May, followed by board consideration in late May if the schedule proceeds. Maxwell asked the committee for feedback on several open points (multiplier for density, road setback language, wildfire/wildland‑urban‑interface precautions and precise eligibility buffers near state and county roads).

No ordinance change was adopted at the meeting. Maxwell told the committee she will bring a public‑notice draft and refined ordinance language for formal review in the next phase.