ADUs, or accessory dwelling units, have been around for some time. They are also called granny flats, in-law units, tiny homes, or carriage houses. They can solve a number of issues, such as providing a suitable place for retired people to live, or giving parents the chance to live near you so they feel closer to you. They can be located directly within or attached to the main structure, attached to the main structure, or detached from the main structure. It is likely that an ADU will include its own kitchen and bathroom. ADUs were common in the early 20th century and were often built by people who were already middle-aged or older who offered them to rent as rooms after their children left home.

What should you know if you plan to build an ADU in Berks County?

Types of ADUs

There are several ways you can build an ADU. They include:

  • Detached new construction ADUs, also sometimes called backyard cottages, granny flats, laneway houses, or DADUs.
  • Garage conversion ADUs
  • ADUs above a garage or workshop, or attached to it.
  • Addition ADUs or “bump-out ADUs”:
  • Basement conversion ADUs, also commonly called basement apartments, mother-in-law units, in law units, secondary suites, English basements, accessory apartments, and a host of other names.
  • Internal ADUs, where part of the primary house besides the basement is converted to an ADU.


Building an ADU is much less expensive than building a regular home, although it still requires a significant amount of investment. The basic structure usually costs around $80,000 and goes up quickly from there. Depending on how elaborate the structure is, it can cost as much as $150,000 or more.

It is important to take permits into consideration while building additions to your home. Many homeowners have built illegal additions because of the high permit fees. Make sure you check the fee schedule before you build.


If you want to build an ADU in Reading or the surrounding area, you should check current local regulations before you build as they are subject to change. Here are some guidelines you might find:

  • A tiny house should have sanitary facilities (toilet, sink, and either a bath or shower)
  • The bathroom and kitchen sink have to have both hot and cold water
  • The plumbing fixtures must be connected to an approved sewage system
  • The whole structure has to sit on a foundation which is considered permanent
  • There are a number of things which could be included, and which need to be regulated, such as:
    • Windows
    • Permanent heating facilities
    • Wall-switch lighting
    • Bathroom windows or exhaust fans
    • Smoke alarms
    • A door (leading to the outside) which must be at least 32 inches wide and 78 inches high

Building an ADU on your property can certainly be a good way to address your family's needs. Just make sure you do your research and are ready to make the investment.

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