Accessory Structures in Allentown, PA (2026)
5 verified accessory structures rules for Allentown, Pennsylvania, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Allentown expressly allows accessory dwelling units (ADUs) on lots occupied by a single dwelling unit. An ADU may not exceed 800 square feet or 40% of the principal dwelling's floor area (whichever is less), only one is allowed per lot, at least one unit on the lot must be owner-occupied, and the combined floor area of the principal unit plus the ADU must total at least 1,750 square feet.
ADUs allowed; max 800 sq ft, owner-occupied, 1 per lot
Some RestrictionsCity of Allentown Zoning Ordinance Sec. 660-42 (Ord. No. 16166, adopted Oct. 15, 2025, effective Jan. 1, 2026)
660-42.C REGULATIONS All accessory dwelling units are subject to the general regulations of this subsection. (1) Where Allowed. The number and location of dwelling units tables for each building type in Article 4 identify the zones in which accessory dwelling units are allowed, provided further that: (a) ADUs are allowed only on lots occupied by a single (one) dwelling unit; (b) The total floor...
Shed Rules
In Allentown a storage shed is an accessory structure that generally may not exceed 15 feet in height, may not stand in any front yard, and must be set back at least 3 feet from side and rear lot lines and 10 feet from any street lot line (unless the Article 4 outbuilding tables set a specific figure). A shed of 150 square feet or less may sit on an abutting commonly owned lot. A detached shed not attached to a one- or two-family dwelling or townhouse, or any shed 1,000 sq ft or larger, requires a building permit.
Sheds: 15 ft max height, 3 ft side/rear & 10 ft street setback
Some RestrictionsCity of Allentown Zoning Ordinance Sec. 660-41.B (Ord. No. 16166, adopted Oct. 15, 2025, effective Jan. 1, 2026)
660-41.B GENERALLY APPLICABLE REGULATIONS ... (1) Location. Accessory uses and structures must be located on the same lot as the principal use and principal structure to which they are accessory, except that an above-ground swimming pool or storage shed of 150 square feet or less may be located on a lot abutting a lot occupied by the principal use or structure to which the pool or shed is acces...
Garage Conversions
Allentown allows a detached garage or other outbuilding to be converted to living space as an accessory dwelling unit: an ADU may be created by converting space within an existing outbuilding on a lot occupied by a single principal dwelling, subject to the Section 660-42 ADU rules. Finishing a garage and any change of use require building permits, an outbuilding occupied by an ADU must sit on a permanent foundation, and the converted ADU may not exceed 800 sq ft or 40% of the principal dwelling, whichever is less.
Garage may be converted to ADU; permits required
Some RestrictionsCity of Allentown Zoning Ordinance Sec. 660-42.C(4), (8), (9) (Ord. No. 16166, adopted Oct. 15, 2025, effective Jan. 1, 2026)
(4) Methods of Creation. An accessory dwelling unit may be created through any of the following methods: (a) Converting existing floor area within the interior of a principal dwelling unit; (b) Adding floor area to an existing principal dwelling unit to accommodate an accessory dwelling unit; (c) Constructing an outbuilding (see 660-49) on a lot occupied by a single principal dwelling unit; (d)...
Carport Rules
Allentown requires permits for carport construction. Setback requirements, height limits, and lot coverage maximums apply.
Allentown Carport Construction Rules
Some RestrictionsTiny Homes
Allentown regulates tiny homes differently based on whether they are on a permanent foundation or on wheels. Zoning and minimum square footage requirements apply.
Allentown Tiny Home & Small Dwelling Rules
Some RestrictionsLooking for Lehigh County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Allentown city rules.
Accessory Structures in Lehigh County →