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Connecticut Public Act 17-170 — Accessory Dwelling Unit Framework (CT)

Tracked preemption from the Connecticut overlay bundle.

Overview

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Effective
2017-10-01
Sunset
—
Authority
state
Scope
state:CT
Other Connecticut preemptions
Connecticut Public Act 21-29 — Fair Share Housing FrameworkConnecticut §8-30g — Affordable Housing Land Use Appeals ProcedureConnecticut §8-2 — Home Rule Zoning Enabling Framework

Trigger predicate

When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.

parcel.base_zone_category ∈ {res_sf, res_mf, res_th, mu}

Preempted fields

1 field on the base district schema is rewritten when the trigger fires.

FieldOpValueNote
base_districts[category=res_sf].allowed_usesaddaduPA 17-170 authorizes (does not mandate) ADUs as a permitted use; municipalities retain discretion to set local standards

Citation

Authority source
Connecticut Public Act 17-170 (codified at CGS §8-2 et seq.)
§ PA 17-170 (An Act Concerning Accessory Apartments)
https://www.cga.ct.gov/2017/ACT/pa/pdf/2017PA-00170-R00HB-07277-PA.pdf

Research notes

Weaker than state-mandated ADU regimes (e.g., California's GC §66411.7). PA 17-170 is enabling rather than preemptive — it authorizes municipalities to permit ADUs by-right and provides a framework for local adoption, but does not strip local discretion. Most CT municipalities still require special permits or have adopted only partial frameworks. Subsequent legislative efforts (HB 6107 in 2021) proposed mandatory ADU by-right but the by-right provision was made opt-out, allowing municipalities to opt out by supermajority vote — significantly weakening preemption force.