ADU Basics
What is an ADU?
ADUs (accessory dwelling units) can be freestanding residences on the same lot as a single-family home, or ADUs can be developed within existing buildings, such as in the case of a basement, a bonus room or the space above a garage.
ADUs are an important tool that will enable us to quickly add year-round rental housing.
Making ADUs easier for homeowners to build could yield up to 1,000 new units in just a few years when larger housing developments take 5, 10, or even 15 years to permit and build.
ADUs on Cape Cod
For years many towns on Cape Cod prohibited building ADUs. Governor Baker’s Housing Choice legislation made it easier for towns to pass updated bylaws to allow ADUs, and most towns have done so.
The towns of Falmouth and Brewster have had promising success with early efforts to promote ADU construction after the new bylaws passed, with new permits approved for 21 and 26 ADUs respectively. That’s a significant number of new units added to town inventory quickly and at no cost to taxpayers.
ADUs can take many forms depending on the property: detached, attached addition, or part of the existing house.
Benefits of ADUs
- ADUs can be permitted and built quickly in a matter of months – that’s the speed we need to address our urgent housing crisis
- Bylaws require year-round leases so they won’t be diverted to short-term rentals
- Built within existing wastewater limitations and with minimal tree clearing
- Optimize the use of existing single-family homes
- Blend into the neighborhood context
- Enable homeowners to generate income from what is usually their single largest asset
- Can be built without significant public investment
- Create flexibility in home use as a homeowner’s needs change throughout their life
My Home Plus One ADU Program
Housing Assistance created the “My Home Plus One” ADU Program to assist Property Owners with the creation of year-round rentals. The program operates on two fronts:
- We will provide technical assistance to property owners in determining the initial feasibility of constructing an ADU on their property.
- Additionally, we will offer a financial incentive, to those that qualify. This incentive is intended to help supplement costs and encourage property owners to create year-round rentals. *No funds are available.
Before you begin an inquiry it is important to review the factors below.
Steps to Building an ADU
- Step 1: Initial Project Feasibility
View Technical Assistance for more information. - Step 2: Project Design
- Step 3: Permitting & Contractor Bidding
- Step 4: Build Out & Contractor Management
- Step 5: Tenant Selection & Lease-Up
My Home Plus One ADU program will help homeowners create ADUs, and gain practical experience that will help us refine the program and its marketing. We’ll share findings and recommendations for replicating this program elsewhere in the state with other groups such as our peer members in the Regional Housing Network or other Community Development Corporations.
Construction Obstacles
Cost
Before beginning any construction project, it is important to consider the estimated cost of construction and the return on investment you need to make the project feasible. This will vary based on your own personal financial situation and project goals.
Zoning
Each Town has unique zoning requirements that regulate what you can or cannot build on your property. You can check your Towns ADU zoning rules HERE.
Site Constraints
Your property will need to have the physical space to site the new ADU, taking into consideration zoning setbacks, wetlands, parking needs, site access, and other existing site conditions.
Wastewater Capacity
To assess whether your property can support an ADU you will need to understand if your septic or sewer capacity will support an additional bedroom. If not, you will need to decide if you are willing to remove a bedroom from your existing primary dwelling or contact a septic engineer to determine whether or not you can expand your existing system.
Covenants
If the property is part of a subdivision there may be covenants (rules) that will not allow ADU construction. You will need to review your property deed, or you may contact a Title Search Specialist or Town Building Department or Planner for assistance.
Homeowners Association Bylaws
Homeowners Associations frequently have bylaws that prohibit secondary units. Review your Homeowners Association Bylaws to determine if ADU construction is allowable.
Becoming a Landlord
Building an ADU and becoming a landlord requires a significant personal and financial investment. Prior to beginning the process of assessing your ability to build an ADU, it is important to weigh the risks, benefits, and responsibilities associated with becoming a landlord. FannieMae has developed a great resource to guide you through this process: Becoming a Landlord: Rewards, Risks, and Responsibilities. The guide’s purpose is to help you and other first-time landlords understand the risks and responsibilities involved in the business of being a landlord and to share some proven ways of handling them successfully.
