What is an Accessory Dwelling Unit (“ADU”)

An accessory dwelling unit (ADU) is a smaller, independent residential dwelling unit located on the same lot as single-family home. ADUs go by many different names throughout the U.S., including accessory apartments, secondary suites, mother-in-law suites, and granny flats. ADUs can be converted portions of existing homes, additions to new or existing homes, or new stand-alone accessory structures or converted portions of existing stand-alone accessory structures. 

Examples include:

-  an apartment over the garage;

-  a small living quarters on a separate foundation in the backyard;

-  a space within the primary residence with a separate entrance; or

-  a space within the primary residence using the same entrance as the homeowners.

Local ordinances specify the allowed ADU types. Broomfield is currently considering an ADU ordinance and does not have one in place at this time.


How are utilities supplied to an ADU, i.e. water, electricity?

-  Private utilities such as electricity, gas, cable, and internet are typically addressed by the property owner and private utility provider. Gas or electric service is required to meet applicable building codes.

- Water and sewer service requirements are typically specified in local ADU ordinances (as adopted). Broomfield is currently considering an ADU ordinance and does not have one in place at this time. Water and sewer service expansion fees are also being discussed.

What issues must be addressed when considering an ADU?

ADU ordinances often include requirements for lot sizes, setbacks, parking, utility connections, and design criteria.

Why build an ADU? – Primary reasons are to gain income or to house a family member?

ADUs provide an opportunity to house a family member, gain additional income, and provide affordable or attainable housing for others.