ADU Guide · Verified 2026
Building an ADU in Pennsylvania
Pennsylvania has no statewide ADU law yet, but House Bill 2186, part of Governor Shapiro's housing agenda, passed the state House with bipartisan support and now awaits Senate action. Philadelphia is currently the most permissive major city in the state.
Quick Facts
Statewide floors set by No statewide law yet; HB 2186 passed the House, pending in the Senate. Your city may be more generous but cannot go below them.
The Three Types of ADU
A real bill, genuinely advanced, not yet law
HB 2186 has already cleared a real, meaningful hurdle, passing the full Pennsylvania House with bipartisan support, but a bill passing one chamber is not the same as becoming law. It still needs Senate passage and the Governor's signature before it changes anything statewide.
Part of a broader, named policy push
HB 2186 sits inside Governor Shapiro's wider housing agenda, unveiled in February, giving it real political momentum, though momentum alone doesn't make it current law.
Philadelphia is the practical leader for now
Absent a statewide law, Philadelphia's own zoning code is generally considered the most ADU-permissive among Pennsylvania's major cities, a real local exception to the rest of the state's more restrictive default.
What people get wrong
The most common mistake is treating HB 2186 as if it were already law because it passed the House. It has not passed the Senate or been signed as of this research, so today's actual rule in Pennsylvania is still whatever the specific municipality's own zoning code says.
From Idea to Move-In: The Timeline
Who Administers It
Counties With Their Own Rules
These Pennsylvania counties have verified, county-specific ADU rules that add to the state baseline:
Building It Yourself? Here's What You'll Need
Planning an ADU? Tools homeowners use in the design and layout phase:
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Check Your Local Rules
Your city may allow more than the state floor
State law sets the minimum; many Pennsylvania cities and counties are more generous. Browse the full directory of 67 counties and every city in Pennsylvania for local rules, fees, and building department contact details.
Browse the full Pennsylvania directory →Not sure if your project needs a building permit, a zoning approval, or both? See our guide to building permits vs. zoning approval.
Official Sources
ADU law changes frequently and local ordinances add detail. This guide is general information, not legal advice, always confirm with your local building department. Reviewed by the StateDataIndex Editorial Team · Updated September 2026.