5 county-level rules, plus city-specific rules for 3 cities in Allegheny County, Pennsylvania.
Verified from official government sources
Allegheny County has no countywide ADU mandate. Pennsylvania does not require municipalities to permit accessory dwelling units. Most Allegheny County municipalities limit ADUs to specific zoning districts or prohibit them outright. Pittsburgh allows ADUs citywide as of 2023 zoning amendments.
Sheds in Allegheny County are governed by municipal zoning. Most municipalities exempt sheds under 200 sq ft from UCC building permits but require zoning permits for placement and setbacks. Typical rear/side setbacks: 3-10 feet.
Garage conversions to living space in Allegheny County require full PA UCC building permits covering structural, insulation, egress, ventilation, and electrical work. Zoning approval is separate and often requires off-street parking replacement.
Carports in Allegheny County require zoning approval and, if over 200 sq ft or attached, a PA UCC building permit. Front-yard carports are generally prohibited in most municipalities; driveway-side or rear placement with setbacks is typical.
Tiny homes in Allegheny County must meet PA UCC standards, which require minimum ceiling heights (7 ft), egress, and habitable-space dimensions. On-wheels tiny homes are treated as RVs and cannot be occupied as permanent dwellings on residential lots outside approved RV parks.
3 cities in Allegheny County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
See every category we cover for Allegheny County — parking, noise, fences, fires, animals, pools, and more.
Allegheny County Ordinance Hub →