Key Facts Ordinance Text Full Breakdown Violations FAQ Sources More in Delaware County

Delaware County, PA Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified July 2026

ADU rules in Delaware County, PA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

County ADU rule: None; municipal only
Governing law: PA MPC, 53 P.S. §10603
Who decides: Your borough or township
Municipalities in county: 49
Where to check: Local zoning ordinance

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Pennsylvania under recent ADU streamlining laws. The Delaware County, PA rules below cover local size, height, and setback requirements.

Summary

Delaware County does not regulate accessory dwelling units. Under Pennsylvania's Municipalities Planning Code, zoning (including whether an ADU or in-law suite is allowed) is set by your borough, township, or city. Check your local zoning ordinance.

These county ordinances apply to unincorporated areas of Delaware County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

Zoning ordinances may permit, prohibit, regulate, restrict and determine ... Size, height, bulk, location, erection, construction, repair, maintenance, alteration, razing, removal and use of structures.

View official code

Full Breakdown

Pennsylvania counties do not adopt land-use zoning. The Municipalities Planning Code (Act 247 of 1968, 53 P.S. §10101 et seq.) delegates zoning to each of Delaware County's 49 municipalities. Section 603(b) authorizes a municipality's zoning ordinance to regulate the size, height, location, and use of structures and the areas of land they occupy. Whether an accessory dwelling unit, in-law suite, or second unit is permitted, and any owner-occupancy, size, or parking conditions, are defined in your municipal zoning code. Media, Radnor, Upper Darby, and Chester each set their own rules; there is no countywide ADU standard.

Violations & Fines

Zoning violations are enforced by the municipality through its zoning officer and district magistrate, typically as summary offenses with daily fines set by local ordinance.

Frequently Asked Questions

Does Delaware County allow ADUs?

The county has no ADU rule. It is entirely a municipal zoning question decided by your borough, township, or city under the state Planning Code.

Which law governs ADU zoning in PA?

The Municipalities Planning Code, 53 P.S. §10603, empowers each municipality to regulate the use, size, and location of structures including ADUs.

Sources & Official References

Other rules in Delaware County

Parking Rules: Overnight ParkingSome Restrictions Animal Ordinances: Dog Leash LawsSome Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Abandoned VehiclesSome Restrictions Animal Ordinances: Wildlife FeedingSome Restrictions

All Delaware County rules

How Delaware County compares: Easiest Cities to Build an ADU·Compare Delaware County to another location·View the Pennsylvania accessory structures overview

See something wrong?

Help us keep this page accurate. If you notice an error or outdated information, let us know.