Types of ADUs

ADU stands for Accessory Dwelling Unit, also known as second units, granny flats, in-law apartments, backyard cottages, and a myriad of other terms. These units are self-contained, fully functioning homes that include a kitchen, a bathroom and a place to sleep. ADUs are smaller than the main home and legally permitted.


Accessory Dwelling Unit

ADUs can range in size from studio apartments to multi-bedroom units, and can be created through new construction or interior conversion.

  • New construction
    -Attached: an extension of the main home
    -Detached: a cottage or modular home

  • Conversion of existing interior space
    -Unconditioned space such as a garage, attic or basement
    -Conditioned space such as a bedroom, family room or other


Junior Accessory Dwelling Unit

A JADU (Junior Accessory Dwelling Unit) is a specially permitted type of interior conversion of conditioned space. Limited to 500 square feet, a JADU starts with a spare bedroom and adds an efficiency kitchen and an exterior entrance. It may share a bathroom and heating system with the main house. A JADU is typically the easiest and lowest cost way to create a private unit.


Home Sharing

Depending on your needs and your home’s layout, home sharing may be a great way to earn rental income without taking on a construction project. Homeowners can rent out spare bedrooms and designate spaces within their home for shared use. This option can provide financial security, mutual assistance such as sharing household chores, and create a new sense of community.  Local non-profits can help find suitable housemates and assist with screening. This option provides less privacy for the homeowner than a JADU or ADU, but lots of benefits with little upfront cost. If the homeowner wants to evaluate this option, a Lilypad Homes Feasibility Assessment can help assess the space for the possibility of home sharing and provide guidance on next steps. 


Learn about the types of units, their benefits and relative costs, along with the basics of what’s allowed in your town. We’ll explain the process of creating an ADU or JADU and help you determine the next steps.


We will assess your property and identify the options for creating your ADU or JADU.