ADU Design in Cassandra, PA

ADU Design in Pennsylvania: what governs your project

Pennsylvania has no statewide ADU statute; accessory dwellings are governed by each municipality's zoning ordinance under the Municipalities Planning Code. Philadelphia and Pittsburgh have their own ADU provisions, but standards vary widely across townships and boroughs.

Energy code

Permitting varies by jurisdiction: many Pennsylvania municipalities require conditional-use or special-exception approval for ADUs, with local rules on size, parking, and owner occupancy. Older boroughs may need variances for setbacks and lot coverage.

Permitting & plan check

Pennsylvania's Uniform Construction Code is enforced by local code officials, giving the state a consistent base code with local administration. Philadelphia and Pittsburgh run large electronic review operations with detailed checklists; historic review in Philadelphia and smaller boroughs can add architectural layers on top of technical review.

Good to know

• Erie and the northwest corner sit in a heavy lake-effect snow belt with some of the highest design snow loads in the eastern United States.
• Southeastern Pennsylvania's limestone geology makes karst sinkholes a routine geotechnical concern around Allentown, Harrisburg, and Lancaster.
• The anthracite coal region of northeastern Pennsylvania carries legacy mine-subsidence risk that still affects new construction.

Every discipline, one team