ADU rules in Pittsburgh

Pittsburgh's Zoning Code allows accessory dwelling units only inside a mapped Accessory Dwelling Unit Overlay District under § 912.08, and no such district is in effect today. The one district ever adopted covered about 1,493 predominantly R1-zoned parcels in Garfield (Ord. No. 32-2018, eff. 9-10-2018) and was expressly a pilot: § 912.08.B limits an interim ADU Overlay District to twenty-four months from its effective date unless made permanent first, and City Council never passed a permanence or extension ordinance. Outside such a district the by-right residential accessory uses listed in § 912.02 do not include a dwelling unit, and the § 911.02 Use Table defines Single-Unit Detached Residential as 'the use of a zoning lot for one detached housing unit', so a second detached house on the lot is not an allowed use anywhere. A citywide by-right ADU allowance was recommended to City Council by the Planning Commission on 1-28-2025 but had not been introduced as a Council bill as of 8-4-2026.

Internal and attached ADUs get exactly the same treatment as detached ones: § 912.08.D.2 defines an Accessory Dwelling Unit as a unit that 'may be an independent dwelling unit within a primary structure, a detached structure, or a dwelling unit located within an existing accessory structure', and all three forms are permitted only inside an ADU Overlay District, of which none is currently mapped. A basement, attic or garage conversion is therefore no more available than a backyard cottage. Homeowners in the R2, R3 and RM districts do have a separate, non-ADU route: the § 911.02 Use Table permits Two-Unit Residential by right in R2, R3 and RM (Three-Unit in R3 and RM, Multi-Unit in RM), so converting a house into a legal duplex is possible there subject to the district's minimum lot size per unit and to building and occupancy permits. That route is closed in the R1D and R1A single-unit districts, where Two-Unit Residential carries no entry in the Use Table.

These figures describe what an ADU could be inside an Accessory Dwelling Unit Overlay District; because none is mapped, nothing is buildable under them today. § 912.08.D.2 defines an ADU as 'a dwelling unit smaller than 800 square feet in area', so 800 sq ft is a definitional ceiling rather than a permit standard: a larger unit is simply not an ADU. § 912.08.E.5 caps height at two stories or thirty feet, and § 912.08.E.6 exempts ADUs from the underlying district's minimum lot size and minimum lot size per unit, while § 912.08.E.7 keeps every other development standard of the underlying district in force. The citywide proposal the Planning Commission recommended in January 2025 would raise the cap to 1,000 sq ft per ADU and allow two per residential lot, but it is not law.

§ 912.08.E.4 requires that 'the owner of a property with an Accessory Dwelling Unit must reside on-site', and § 912.08.E.8 makes the duty permanent and ongoing rather than a one-time application test: before a Certificate of Occupancy issues, the applicant must record a deed restriction obliging current and future property owners to keep complying with § 912.08.E. Nothing in Pennsylvania law preempts that requirement; the Municipalities Planning Code (Act 247 of 1968) is enabling legislation only and imposes no ADU mandate, and the 2025-2026 session's ADU bills (HB 2186, SB 1256) have not been enacted. Note that this standard currently governs nothing, because no ADU Overlay District is in effect. The pending citywide proposal would drop owner occupancy entirely.

§ 912.08.E.9 states that 'Accessory Dwelling Units shall be exempt from the on-site parking requirements of Section 914', so no additional off-street space would be required for an ADU inside an overlay district. Chapter 914's parking minimums otherwise still apply to development in Pittsburgh generally: the parking-minimum reform in the Mayor's 2025 Housing Needs Assessment zoning package was recommended by the Planning Commission but has not been enacted. On-street parking is rationed separately in permit areas under Title 5 Ch. 549, whose § 549.08 includes a distinct short-term rental permit category. Like the other § 912.08 standards, this exemption is dormant until an ADU Overlay District exists.

There is no administrative route to an ADU in Pittsburgh today. Inside an ADU Overlay District the unit itself would be an accessory use subject only to the § 912.08.E standards plus a Certificate of Occupancy and a recorded deed restriction, with no Zoning Board hearing. Creating the district, however, is legislative: § 912.08.C requires that adoption of both a preliminary and permanent ADU Overlay District proceed 'in accordance with the Zoning Map and Text Amendment Procedures of Section 922.05', which means a Planning Commission public hearing and recommendation followed by a City Council ordinance. Because an individual homeowner realistically cannot obtain that, the review path is recorded here as discretionary rather than permitted.

Inside an ADU Overlay District, § 912.08.E.2 provides that 'no Accessory Dwelling Unit may be leased for a period shorter than thirty (30) days', which rules out short-term rental of the unit; § 912.08.E.3 allows only one ADU per zoning lot and § 912.08.E.10 allows one only where the primary structure has no more than one legally established dwelling unit. Because the owner must live on site and that obligation is recorded as a deed restriction, an ADU could not be sold off separately from the main house. Separately and citywide, any residential rental needs a Residential Housing Rental Permit: Title 7 § 781.02 makes it unlawful to collect rent for a rental unit without one, and § 781.01(i) expressly sweeps in 'domiciles used by owners as short-term homestays and experiences'. Pittsburgh still has no short-term rental zoning or licensing ordinance; Council Bills 2026-0009 (zoning) and 2026-0008 (PLI licensing) were both pending at a Planning Commission briefing on 7-28-2026, with the hearing set for 9-8-2026.