Accessory dwelling units (ADUs) provide a smart and flexible way for Pennsylvania homeowners to maximize the value of their property. They can generate steady rental income or create a comfortable, separate space for aging parents or young adults who need an affordable place to start. ADUs unlock real value, but you need to understand the rules before you move forward.
Not every part of Pennsylvania permits ADUs, and the requirements shift from one jurisdiction to another. To save you hours of searching, we pulled together the key information you need to figure out what your area allows and how to get started the right way.
Are ADUs Allowed in Pennsylvania?
ADUs are allowed in Pennsylvania, although the rules shift from one county to the next. The state does not set uniform standards, so each township, borough, city, or town creates and enforces its own requirements. The only way to confirm what applies to your property is to check with your local officials.
To make your search easier, you will find county and city contacts below along with their ordinances.
ADUs That Are Allowed in Pennsylvania
Most places in Pennsylvania set ADU size limits in the 400 to 1,000 square foot range, although each locality sets its own rules. All of the ADUs shown below fit within that range and can be used in Pennsylvania as long as your local zoning allows ADUs.
The A-Frame ADU
The Grove ADU
The Luna ADU
The Rivara
The Sonoma ADU
What Is Considered An ADU in Pennsylvania?
What is considered an accessory dwelling unit in PA can vary by jurisdiction, but in general, an ADU is a secondary, independent living space on the same property as a primary residence that includes its own kitchen, bathroom, and sleeping area. Local rules determine if an ADU can be connected to the main dwelling, built as a standalone structure, or allowed in both forms. To see how your jurisdiction defines an ADU, move to your municipality below and review the details.
Can Park Model Tiny Homes Be Used As ADUs?
Yes, some areas may allow park model homes to function as ADUs. They must meet specific standards to qualify as permanent dwelling units. Park model tiny homes are built to RVIA codes and are often treated as mobile homes, so many places do not accept them as long-term housing.
For clarification, review our tiny home regulations in PA guide, which explains how counties and cities classify park models for permanent use. As always, confirm the rules with your local officials listed below. If you want to learn more about the difference between park model tiny homes and ADUs, check out our clear-cut guide comparing the two.
Can Log Cabins Be Used As An ADU?
They can be, but only if they meet the size, height, and placement requirements for ADUs in your area. Typically, ADUs in PA must be at least 400 square feet and not larger than 700 to 1,000 square feet. Some models, like Zook Cabin’s Lariat and Wrangler, start at around 600-700 square feet, which meet most ADU requirements. Of course, other models may be permitted; it all depends on what your area allows.
Can Modern Cabins Be Used As An ADU?
It also depends on where you live, but they certainly could be! As noted earlier, Pennsylvania typically requires ADUs to fall between 400 and 1,000 square feet. This makes many modern cabin models, like the ones from Zook Cabins, eligible for use as ADUs. Check in with your local officials so you know exactly how they handle modern cabins used as ADUs.
What is the Difference Between a Prefab ADU & a Modular ADU?
The difference mainly involves how they are constructed and how they arrive at your property.
Prefab ADUs are built in a factory and arrive at your property as a complete, finished structure that just needs to be placed on site.
Modular ADUs are built in sections. Then, these separate sections are delivered to and assembled on your property.
Our guide on prefab and modular ADUs provides a more detailed look at the differences between the two structures.
What is the Minimum Size for an Accessory Dwelling Unit?
There is no statewide minimum square footage for accessory dwelling units. However, most areas require that they be at least 400 square feet. Because requirements can shift from place to place, it’s essential to check with your local officials to see what they allow.
Can My ADU be Bigger Than My House?
No, nearly every area in PA requires that the height of your ADU does not exceed that of your principal residence. In fact, some areas even have height restrictions below that. To find out what your local code requires, skip to your city below.
Do You Need A Permit For An ADU in Pennsylvania?
Yes. Every ADU will need permits before construction starts. Some places require a building permit or zoning approval, while others have a permit created specifically for ADUs. You may also need separate permits for electrical, plumbing, or HVAC work. Because requirements change from one jurisdiction to another, it’s essential to check with your local officials so you know exactly which permits apply.
Are There Any Incentives or Grants for ADUs in Pennsylvania?
There are no Pennsylvania state programs that provide grants or other incentives for ADU construction. However, there may be some financing available through local programs, so be sure to check with your local community development or planning department to determine what is available to you.
What Features are Included in An ADU from Zook Cabins?
While specific features vary by model, our ADUs offer a range of modern designs with various floor plans, allowing you to select the one that best fits your needs, including:
- Fully finished interiors
- Floor plans featuring multiple bedrooms and bathrooms
- Sizes ranging from 571 to 848 sq. ft.
- Heating & cooling options
- Insulation
- Options for front porches or loft spaces
- Living Areas with plenty of natural light
It’s important to note that certain interior features, such as countertops, tile work, and cabinet colors, can be upgraded to better match your preferences. Talk to your sales representative to learn more about available customization options.
Are Zook Cabin’s ADUs Built to Code?
Yes! Our models are specifically designed to meet local size and room requirements. Because they are modular homes, they must be installed on a permanent foundation to comply with local building codes. Zook Cabins will help you choose the foundation type that best fits your property and meets local requirements.
Can an ADU Have Multiple Bedrooms and Bathrooms?
Absolutely! As long as they fit within the square footage requirements in your area, you can have multiple bedrooms and bathrooms in your ADU. Zook Cabins offers ADUs with a variety of floor plans and layouts, including options with multiple bedrooms and bathrooms. For example, the A-frame and Grove ADUs both feature two bedrooms.
Are ADUs A Good Investment?
Yes, ADUs can provide a strong return on your investment. Many places allow them to be used as long-term rentals, which creates steady income. They also keep daily expenses lower because of their smaller size.
Beyond the financial side, an ADU gives families a practical way to support elderly parents who want independence with nearby help, or young adults who need an affordable place to begin building their own lives. It creates privacy, safety, and stability without the cost of a separate home.
If you’d like to take the next step, contact us to learn more or request a free quote on any of the models above.
What Are the Requirements for ADUs in Each County in Pennsylvania?
Below you’ll find all 67 counties and the appropriate government contact information to learn more about their ADU regulations. Since regulations are often set by city, township, or borough officials, it’s essential that you check with your local officials for the most accurate look at ADU requirements in your area.
You can skip this list to view the requirements for your city.
Does Adams County, PA, allow ADUs?
Yes, so long as your accessory dwelling unit complies with the following requirements:
- # of ADUs: 1
- Maximum Size: 50% of the existing dwelling unit or 1,000 square feet; whichever is less
- Minimum Size: 400 square feet
- Setbacks and Placement: Must comply with the requirements of your zoning district
For accurate guidance on permit needs and local requirements, contact the Building and Maintenance and Planning and Development Departments.
Does Alleghany County, PA, allow ADUs?
Alleghany County is not responsible for enforcing ADU regulations. This is instead left up to city and town officials within the county. You can skip ahead to the city section to find out what’s required in your area.
Does Armstrong County, PA, allow ADUs?
They currently do not have any clear ADU regulations. The Planning and Development Department can let you know what they allow, but most likely these rules are set by city, town, and other municipal officials. You can skip ahead to the city section to find out what your area allows.
Does Beaver County, PA, allow ADUs?
It appears that the county currently only allows attached accessory dwelling units for elderly parents or other close relatives. However, cities and towns may be able to set their own regulations. To determine what you area allows, check with your local officials below. If you’d like to see Beaver County’s ADU regulations change, contact the Planning Commission.
Does Bedford County, PA, allow ADUs?
Their ADU regulations are unclear. For more information on what the county allows, contact the Planning Department. In most cases, city and town officials are responsible for enforcing their own requirements. You can find city requirements below.
Does Berks County, PA, allow ADUs?
It is unclear if they allow ADUs. The Planning Commission can let you know what the county requires, but if your city or town officials may have a different set of requirements. You can find out what their regulations are down below.
Does Blair County, PA, allow ADUs?
The county does not appear to enforce ADU regulations. If you want clear information on any current requirements, contact the Planning Commission. Many cities and towns handle their own rules, and you can review several of those below.
Does Bradford County, PA, allow ADUs?
It is unclear if they allow accessory dwelling units. For more information on what is currently allowed, contact Community Planning & Mapping.
In many cases, more local departments, like township or city officials are responsible for enforcing ADU regulations. You can find some down below, but be sure to consult with your local officials before adding an ADU to your property.
Does Bucks County, PA, allow ADUs?
There is no legislation at the county level. To determine if ADUs are permitted in your area, it’s recommended that you consult with local officials first. However, if you have any questions about requirements at the county level, you can contact the Planning Commission.
Does Butler County, PA, allow ADUs?
The county does not permit tiny homes and it appears not to allow ADUs as well. For more information on what is permitted, contact the Planning Commission.
Does Cambria County, PA, allow ADUs?
No, the city does not currently allow them. If you’d like to see this change, contact the Planning Commission.
Does Cameron County, PA, allow ADUs?
There are no county wide regulations for accessory dwelling units. To determine if they are allowed, consult with your local officials.
Does Carbon County, PA, allow ADUs?
The county does not currently have ADU regulations. It’s likely that this is left up to local officials, but for more information consult with the Planning and Development Department.
Does Centre County, PA, allow ADUs?
The county does not enforce accessory dwelling unit laws. This is usually the responsible of city or township officials, but you can find out more about county-level requirements from the Planning & Community Development Department.
Does Chester County, PA, allow ADUs?
Yes, but only if it follows municipal rules. The county outlines the zoning ordinances for ADUs in several of its municipalities. If you reside in an unincorporated area and have questions about which requirements apply to you, contact the Planning Commission.
Does Clarion County, PA, allow ADUs?
Their Subdivision and Land Development Ordinance currently makes no mention of accessory dwelling units. This likely means that it’s up to township or city officials are responsible for enforcing their own regulations. However, you can find out more about county level requirements from the Planning Department.
Does Clearfield County, PA, allow ADUs?
Their county code makes no mention of ADUs. With no clear regulations, it’s essential that you check with township or city officials as they likely set the requirements for accessory dwelling units. However, if you have questions about county requirements, contact the Planning Department.
Does Clinton County, PA, allow ADUs?
This is decided by municipalities within the county and not at the county level. To determine if ADUs are allowed in area, consult with local officials. If you have any questions, the Planning & Zoning Department can provide you with more information.
Does Cumberland County, PA, allow ADUs?
Yes, but only in certain municipalities as ADU regulations are not set at the county level. Contact your township or city officials to determine if accessory dwelling units are permitted on your property. If you need assistance from the county, contact the Planning Department.
Does Columbia County, PA, allow ADUs?
Columbia County does not enforce ADU regulations. This is the responsibility of township, city, and other municipal officials, so be sure to reach out to them to determine what is allowed in your area. For more information at the county level, contact the Planning and Development Department.
Does Crawford County, PA, allow ADUs?
This is up to municipal officials, so it varies depending on where you reside in the county. Be sure to check with your township, borough, city, or other municipal officials to determine what is allowed in your area. If you have any questions at the county level, consult with the Crawford County Planning Department.
Does Dauphin County, PA, allow ADUs?
There are no county-wide ADU regulations. To determine if accessory dwelling units are permitted in your municipality, reach out to your township, borough, or city officials. For more information at the county level, contact the Dauphin County Planning Department.
Does Delaware County, PA, allow ADUs?
Currently, the city does not have ADU regulations in place. However, they do appear to be considering implementing their own legislation. You can find out more about this from the Planning Department. However, typically these rules are left up to municipalities within the county, so be sure to check with township, borough, or city officials.
Does Elk County, PA, allow ADUs?
There are no county regulations for accessory dwelling units. This is set by township, borough, and city officials within the county. Be sure to check with these officials before adding an ADU to your property. If you’d like to know more about the requirements at the county level, contact the Planning Department.
Does Erie County, PA, allow ADUs?
The county does not have any ADU regulations. However, the city of Erie does permit them. The answer to this question will vary depending on what municipality you reside in within the county. Contact your township, borough, or city officials to determine what requirements apply. The Erie County Department of Planning and Community Development can provide you with additional insight into what the county allows.
Does Fayette County, PA, allow ADUs?
It is unclear what the county allows. Since they are responsible for enforcing the zoning code for 31 of the 42 municipalities, it’s essential that you contact the Zoning & Planning Department to find out what they allow. However if you reside in one of the following municipalities be sure to check with local officials:
- Perryoplis Borough
- Ohiopyle Borough
- Uniontown
- Connellsville
- Henry Clay Township
- Menallen Township
- South Union Township
- Springhill Township
- Stewart Township
- Washington Township
- Wharton Township
Does Forest County, PA, allow ADUs?
There are currently no county requirements. First, check with your municipal officials to see what they allow. The following municipalities are located in Forest County:
- Barnett Township
- Green Township
- Harmony Township
- Hickory Township
- Howe Township
- Jenks Township
- Kingsley Township
- Tionesta Township
- Tionesta Borough
For more information at the county level, contact the Planning Department.
Does Franklin County, PA, allow ADUs?
The county doesn’t have any ADU regulations. To find out if accessory dwelling units are permitted where you live, contact your township, borough, or city officials. For more information at the county level, contact the Franklin County Planning Department.
Does Fulton County, PA, allow ADUs?
There are no rules at the county level. For more information on whether accessory dwelling units are allows, it’s recommended that you contact your township, borough, or city officials. If you have questions at the county level, consult with the Fulton County Planning Commission.
Does Greene County, PA, allow ADUs?
Yes, the county appears to allow them, but specific details are unclear. For more information, reach out to the Planning and Development Department. In some cases, municipalities may enforce their own regulations. For requirements specific to your area, consult with township, borough, or city officials.
Does Huntingdon County, PA, allow ADUs?
The county does not appear to have any regulations for accessory dwelling units. Many municipalities do enforce their own regulations, so it’s essential to consult with your local officials to determine what they allow. However, if you’re curious about the county’s requirements, contact the Planning & Development Department.
Does Indiana County, PA, allow ADUs?
There are no regulations at the county level. Be sure to check with local officials first to determine if they have any regulations in place. If you have any questions about county requirements, contact the Planning & Development Department.
Does Jefferson County, PA, allow ADUs?
Jefferson County doesn’t have a county-wide municipal code that enforces accessory dwelling unit requirements. Instead, this is the responsibility of municipalities within the county. That means it’s essential that you contact your city, township, or borough officials to learn what their requirements are.
Does Juniata County, PA, allow ADUs?
The county does not enforce ADU regulations. Instead, this is left up to municipalities. Consult with your city, borough, or township officials to find out if accessory dwelling units are allowed in your area.
Does Lackawanna County, PA, allow ADUs?
There are no ADU regulations at the county level. You can find out more about accessory dwelling unit requirements in your are by contacting your city, borough, or township officials. If you have questions about county requirements, contact the Planning and Economic Development Department.
Does Lancaster County, PA, allow ADUs?
Yes, the county does permit them, but specific requirements vary depending on where you live. As always, it’s important that you consult with city, township, or borough officials to determine what the requirements are in your area. If you have any questions about this, contact the Planning Department.
Does Lawrence County, PA, allow ADUs?
There are no county-wide regulations at this time. To determine if they are allowed in your area, consult with your city, county, or township officials.
Does Lebanon County, PA, allow ADUs?
The county doesn’t have any accessory dwelling unit regulations. You can find out if ADUs are allowed in your area by contacting your city, township, borough officials as they are responsible for setting these laws.
Does Lehigh County, PA, allow ADUs?
There are no countywide regulations, but municipalities do enforce their own requirements, so be sure to check with your city, township, or borough officials.
Does Luzerne County, PA, allow ADUs?
The county is not responsible for ADU regulations. This instead falls on municipalities within the county. Check with your city, township, or borough officials to determine what your area allows.
Does Lycoming County, PA, allow ADUs?
There are no county-wide ADU regulations. This is up to municipalities, including city, township, and borough officials. You can find out if accessory dwelling units are permitted in your area by reaching out to them.
Does McKean County, PA, allow ADUs?
McKean County does not set ADU regulations for the entire county. Local jurisdictions manage their own zoning, so contact your city, township, or borough office for accurate guidance. If you need clarification at the county level, reach out to the Planning Commission.
Does Mercer County, PA, allow ADUs?
Mercer County leaves ADU decisions to individual municipalities. Your local zoning office can confirm the rules for your address. For general questions at the county level, the Planning Commission can assist you.
Does Mifflin County, PA, allow ADUs?
Mifflin County does not have county-wide ADU standards. Each community oversees its own land use rules, so check with your local officials. County-level inquiries can be directed to the Planning and Development Department.
Does Monroe County, PA, allow ADUs?
Monroe County does not enforce ADU requirements across the entire county. Cities, boroughs, and townships create their own regulations. For county questions, contact the Planning Department.
Does Montgomery County, PA, allow ADUs?
Montgomery County does not manage ADU zoning at the county scale. Municipal governments decide what is allowed in each community. If you want to confirm anything through the county, the Planning Commission can help.
Does Montour County, PA, allow ADUs?
Montour County does not control ADU permits county-wide. Local governments handle zoning, so reach out to your municipal office. The Planning Commission is available for county-level questions.
Does Northhampton County, PA, allow ADUs?
Northampton County does not regulate ADUs through county-wide zoning. Municipal leaders set the standards for their own areas. If you need county guidance, contact Community and Economic Development.
Does Northumberland County, PA, allow ADUs?
Northumberland County does not publish ADU rules for the entire county. Each municipality manages its own zoning requirements. County questions can be directed to the Planning Department.
Does Perry County, PA, allow ADUs?
Perry County does not oversee ADU zoning. Townships, cities, and boroughs set their own standards, so check with local officials. The Planning Commission can address questions at the county level.
Does Philadelphia County, PA, allow ADUs?
Yes, the county follows the same regulations for ADUs as the city.
Does Pike County, PA, allow ADUs?
Pike County does not define ADU regulations at the county scale. Municipal governments handle their own zoning, so contact your local office. Planning and Mapping can assist with county-level questions.
Does Potter County, PA, allow ADUs?
Potter County does not establish county-wide ADU standards. Townships, boroughs, and cities manage their own codes. For questions that involve the county, contact the Planning Department.
Does Schuykill County, PA, allow ADUs?
Schuylkill County does not oversee ADU regulations for the entire county. Each municipality enforces its own zoning rules. The Planning and Zoning Department can help with county-level inquiries.
Does Snyder County, PA, allow ADUs?
Snyder County does not maintain ADU requirements at the county level. Local zoning authorities decide what is allowed in each area. County questions can be directed to the Planning Commission.
Does Somerset County, PA, allow ADUs?
Somerset County leaves ADU decisions to municipal governments. Reach out to your city, borough, or township office for site-specific rules. The Planning Commission is available for county-level clarification.
Does Sullivan County, PA, allow ADUs?
Sullivan County does not regulate ADUs through a county-wide code. Municipal offices handle all zoning decisions. The Planning and Development office can assist with questions involving the county.
Does Susquehanna County, PA, allow ADUs?
Susquehanna County does not regulate ADUs at the county scale. Each local jurisdiction sets its own standards, so contact your municipal officials. The Planning and Development office can answer county-level questions.
Does Tioga County, PA, allow ADUs?
Tioga County does not administer ADU zoning across all communities. Cities, townships, and boroughs manage their own requirements. For county information, call 570-723-8251.
Does Union County, PA, allow ADUs?
Union County does not maintain county-wide ADU rules. Local governments oversee zoning and can confirm what applies to your property. The Planning Commission can address county-level questions.
Does Venango County, PA, allow ADUs?
Venango County does not publish ADU standards for the whole county. Each municipality controls its own zoning. The Planning Commission can assist with county-related questions.
Does Warren County, PA, allow ADUs?
Warren County does not regulate ADUs county-wide. Local jurisdictions enforce their own zoning codes. If you need county clarification, contact the Planning and Zoning Commission.
Does Washington County, PA, allow ADUs?
Washington County does not define ADU rules for the entire county. Each municipality sets its own zoning requirements. County-level questions can be directed to the Planning Department.
Does Wayne County, PA, allow ADUs?
Wayne County does not enforce ADU regulations across all communities. Municipal governments handle zoning on their own. The Planning Department is available for county questions.
Does Westmoreland County, PA, allow ADUs?
Westmoreland County does not manage ADU zoning county-wide. Local jurisdictions decide what is allowed and can provide site-specific guidance. The Development Department can help with county-level inquiries.
Does Wyoming County, PA, allow ADUs?
Wyoming County does not maintain ADU regulations at the county level. Municipal offices set their own land use rules. For county-related questions, contact the Community Planning Board.
Does York County, PA, allow ADUs?
York County does not establish ADU rules through a county-wide code. Municipalities oversee zoning and can confirm the standards for your location. The Planning Commission handles county-level inquiries.
Find Your ADU Regulations By City in PA
Below are several cities in PA and their ADU requirements. Please note that townships and boroughs often enforce their own regulations, so be sure to check with them to ensure compliance.
Does Philadelphia, PA, allow ADUs?
Yes, but you must meet specific requirements, including:
- Size: No larger than 800 square feet unless it is within a historic structure
- Permitted Zoning Districts:
- Base Zoning District: RSA-5, CMX-1
- Zoning Overlay District: /EDO, /FDO, /FNE, /NDO, /NE, /VDO
- Lot Size: At least 1600 square feet
Be sure to take all necessary steps to get your structure approved with the Department of Licensing and Inspections.
Does Pittsburgh, PA, allow ADUs?
Yes, the city began a pilot program in 2018 and decided to implement the proposed ADU policy from fall 2024 into 2025. Their regulations for ADUs are as follows:
- Max. Height: 2 stories or 30 feet high
- # of ADUs: 2
- Size: 1,000 square feet
Additional requirements apply. It’s essential that you consult with City Planning to ensure your ADU is in compliance with the city’s regulations.
Does Allentown, PA, allow ADUs?
The city planned to update their ordinance to allow ADUs, but whether these regulations are in place are unclear. You can contact the Community & Economic Development Department to find out what requirements are currently in place. However, these were some of the proposed requirements for ADUs in the city:
- Min. Floor Area: The combined floor area between the primary dwelling and accessory dwelling unit must be at least 1,750 square feet.
- # of ADUs: 1
- Max. Size: 800 square feet
Again, it is unclear if they are currently in effect, so be sure to consult with the Community and Economic Development Department.
Does Reading, PA, allow ADUs?
It is unclear if the city allows them. For more information on what is currently allowed, contact the Zoning Department.
Does Erie, PA, allow ADUs?
Yes, it appears the city allows them, but specific details are unclear. For more information, contact Planning & Neighborhood Resources.
Does Bethlehem, PA, allow ADUs?
There is no ADU legislation in place at this time. However, the city has introduced a pilot program to begin considering zoning reform for accessory dwelling units. You can find out more about the status of the pilot program from the Planning and Zoning Department.
Does Scranton, PA, allow ADUs?
It is unclear if they city allows them. For more information on current ADU regulations, contact the Planning and Zoning Department.
Does Lancaster, PA, allow ADUs?
The city has considered allowing accessory dwelling units, but it currently does not have legislation in place. For more information on the status of their ADU regulations, contact the Bureau of Building Code Administration.
Does Harrisburg, PA, allow ADUs?
Yes, so long as it meets the following requirements:
- Maximum Size: 33% of the square footage of the principal dwelling unit
- Owner-Occupancy: Required for the principal dwelling
Additional requirements may apply. Be sure sure to check with the Building & Housing Department.
Does York, PA, allow ADUs?
Yes. The city has the following regulations in place for accessory dwelling units:
- Minimum Size: 400 square feet
- Maximum Size: 700 square feet; no more than 50% of the principal dwelling unit
- Number of Occupants: No more than 2
It’s essential that you connect with the Bureau of Planning & Zoning to ensure your ADU complies with all applicable regulations.
Searching For An ADU Builder Serving Pennsylvania?
Now that you have a clearer understanding of the ADU requirements in your area, it’s time to find a builder that can help you construct your dream home in compliance with local code. If you’re looking for an ADU builder in PA, you’re in the right place.
Zook Cabins is an ADU builder based out of PA that specializes in working with you to make your dream ADU a reality. All you need to do is request a quote for what you’re looking for, and we’ll work with you to build the ADU you want. Please don’t hesitate to contact us with any questions!
Tiny Home & ADU Rules By State: See How They Compare?
In some cases, park model tiny homes can be used as ADUs, while in others, they can’t. As you’ve come to learn, this really depends on where you live. If you’re interested in utilizing a park model tiny home as an ADU, but are wondering where it’s allowed, you can use the chart below to check out tiny home regulations across the U.S., including in PA.