ADU rules in Erie

A detached backyard ADU is a by-right permitted use in every one of Erie's residential districts. Section 204 lists 'Accessory dwelling unit (ADU)' under '(a) Permitted uses' in R-1, R-1A, R-2, R-3 and RLB, and also in C-1, C-4, M-1 and the W-R Waterfront Residential District, so no hearing before the Zoning Hearing Board or City Council is involved. Section 601 expressly recognizes the detached form: a detached ADU 'is structurally separate from the primary dwelling' and 'can be built as a stand-alone unit or added to an existing structure such as a detached garage.' The use is not listed at all in C-2, C-3, M-2, the IP Industrial Park district or the W-C, W-C2, W-C3 and W-M waterfront districts, where it is therefore prohibited.

Section 204 lists a single use, 'Accessory dwelling unit (ADU)', without distinguishing form, and section 601 defines that use to cover all three configurations: an interior ADU that 'utilizes existing space within the primary dwelling through the conversion of an interior room such as an attic or basement,' an attached ADU 'added to the front, side or rear of the primary structure, or constructed above an attached garage,' and a detached ADU. A basement or attic conversion and a rear addition are therefore permitted by right in the same nine districts as a detached unit. Interior and attached units still have to meet the district's front, side and rear yard requirements under section 205.8, which applies the principal-building setbacks to anything attached to the principal structure.

Erie's ordinance sets no size standard written specifically for ADUs: section 204 lists the use with no cross-reference to a supplemental-standards subsection, unlike neighbors on the same lists such as 'Short-term rental (Section 305.49)' or 'Townhouses (Section 305.13)'. The operative ceiling for a detached unit is therefore the general rule in section 205.9, which says that in any R District 'Detached accessory buildings shall be no larger than 720 square feet in size or 15 feet in height' and must sit in the side or rear yard, at least six feet from any dwelling or alley and three feet from any side or rear property line. Interior and attached ADUs are bound only by the district envelope in section 205: maximum lot coverage by buildings of 35% in R-1 and 50% in R-1A, R-2, R-3 and RLB, and maximum structure heights of 35 feet in R-1 and R-1A, 45 feet in R-2, 100 feet in R-3 and 60 feet in RLB. Because the 720-square-foot figure comes from the accessory-building rule rather than from ADU-specific text, confirm it with the Zoning Office before designing to it.

Nothing in the Erie Zoning Ordinance conditions an ADU on the owner living on the property. A full-text read of Article 1303 turns up no occurrence of 'owner-occupied', 'owner occupancy', 'principal residence' or 'shall reside' anywhere, and the section 601 ADU definition imposes only that the unit's 'use is secondary to that of the principal dwelling or building on the same lot.' Owner occupancy surfaces in Erie's code only as a benefit rather than a condition: Article 330 exempts owner-occupied flats and duplexes from the annual rental fee and inspection where the second unit stays vacant (§ 330.04(a)(7)), and exempts a dwelling where a parent, parent-in-law or adult child of the owner remains in occupancy and no net income is earned (§ 330.05(d)). Pennsylvania has no statewide ADU statute that would add or preempt such a requirement.

Section 302.4 requires off-street parking 'for any new use hereafter established or for the enlargement to any existing use' and sets the residential rate at '1 per family living unit', so an ADU as a second dwelling unit draws one space. Section 302.6 then cuts that: properties in the RLB, C-1, C-4, W-C2 and W-C3 districts provide 50% of the schedule, and properties in C-3 provide none at all, though ADUs are not a listed use in C-3. Under section 302.9 residential parking 'must be on the same lot or a lot which directly abuts the residential use, if under the same ownership', so an off-site space down the block will not count. Erie's ordinance offers no transit-proximity or small-unit exemption.

The ADU appears under the '(a) Permitted uses' heading in each of the nine districts that allow it, never under '(b) Special exceptions' or '(c) Conditional uses'. Section 204 reserves conditional uses for City Council after a Planning Commission recommendation and special exceptions for the Zoning Hearing Board, so a by-right listing means neither hearing applies. The path is administrative: the Zoning Officer administers the ordinance and issues zoning certificates (§ 401.1 and § 401.2), and building permits for one- and two-family work are taken out over the counter at Code Enforcement in Room 407 of the Municipal Building, with the city's residential permit page noting an additional $25.00 charge for zoning approval on top of the construction-cost-based building permit fee. The one discretionary overlay is historic: in a locally designated historic district or on a designated historic resource, section 708.1(c)(2)(B) requires a certificate of appropriateness for construction of accessory buildings, and section 708.1(b) makes a building or zoning permit application incomplete without it.

The zoning ordinance places no limit on renting an ADU long-term, and there is no primary-residence test. What does apply is Article 330: it is unlawful to 'operate, let or rent to another for occupancy any residential rental unit' without both a residential rental registration (§ 330.03(a)) and a residential rental license (§ 330.04), the license running two years with an inspection at least every two years. A unit occupied by the owner's parent, parent-in-law or adult child is outside the definition of 'residential rental unit' and is expressly exempt where no net income is earned (§ 330.05(d)). Short-term rental is a separate zoning use, not a way of using an ADU: a short-term rental license is required before renting for fewer than 30 consecutive days (§ 305.49(a)(1)), the license is annual with annual inspection and does not run with the property, and the city's handout states that zoning approval and a zoning certificate must issue first. Short-term rental is listed as a permitted use in R-1, R-1A, R-2, R-3, RLB, C-1, C-2, C-3, C-4, W-C, W-C2, W-C3 and W-R but not in M-1, so an M-1 ADU can be rented long-term only. The ordinance is silent on selling an ADU separately from the principal dwelling.