Guide to Accessory Dwelling Units


Accessory Dwelling Units, or ADUs, as they’re usually called, have become a widely popular option for modern housing solutions as they successfully mix convenience and usefulness. We’ve gathered valuable insights from professionals specializing in Cape Cod home additions and compiled them in an easy-to-understand guide to clarify the idea of ADUs by highlighting their different facets, varieties, and prospective advantages.

What is an ADU unit? 

Essentially, an ADU is like having a separate living space right on your property alongside your main home. ADUs are built to act as standalone living areas, with their own entrance, kitchen, bathroom, and living spaces. These versatile units are called granny flats, guest houses, or backyard cottages, and they provide an effective solution to the evolving needs of homeowners and communities.

ADUs can serve many purposes and cater to a diverse range of scenarios. Homeowners often utilize them to house aging parents or to provide accommodation for family members. On the other hand, some see them as an opportunity for rental income. ADUs can also contribute to addressing the increasing demand for housing in more urban areas, promoting efficient use of land and resources.

What are the types of ADU units?

What is an ADU unit?

ADUs come in various shapes and sizes, individually tailored to suit different needs, preferences and property constraints. Understanding the different types of ADUs can help homeowners to make informed decisions that align with their goals. So here are the most common types of ADUs:


These units are integrated into the primary residence and seamlessly incorporated into existing structures. Converting a basement, garage, or unused space into a functional living area are some of the typical examples. This type of ADU benefits from the existing infrastructure of the main house, reducing construction costs and time.


As the name implies, detached ADUs are standalone structures separate from the main house. They’re often built in the backyard, which makes them an ideal solution for homeowners who wish to maintain privacy and preserve the aesthetics of their primary residence. Detached ADUs offer greater flexibility in design, layout, and orientation.

Garage conversion 

This type of ADU involves transforming an existing garage into a livable space. With careful planning and design, a garage can be converted into a cozy dwelling while retaining its structural integrity. Garage conversion ADUs are a very sustainable option that repurposes underutilized space and minimizes the need for new construction.

Above garage 

Units situated above detached garages use vertical space to create a functional living area. Above-garage ADUs are particularly popular in urban areas where land availability is quite limited. They offer a unique vantage point and often feature elevated privacy.


Transforming a basement into an ADU is a practical way to maximize the utility of existing space. Basements are a blank canvas for creating comfortable living quarters, with natural insulation and the potential for ample lighting.

Accessory Dwelling Units are a contemporary solution that perfectly  harmonizes modern living needs with sustainability and adaptability. The diversity of ADU types ensures that homeowners can find an option that suits their vision and requirements. As the housing landscape evolves, ADUs are a perfect example of the power of innovation in creating flexible and inclusive living spaces.

Where can I find a professional Cape Cod home additions company? What is an ADU unit?

If you’re interested in building an ADU, it’s recommended that you begin by consulting with a professional contractor. With proper guidance, you can explore the practical benefits of ADUs and determine if they’re a good fit for your property and community. If you wish to add a second story to your house, or a different type of ADU, our experts will gladly explain the process, expenses and long-term value of such an endeavor to help you make an informed decision. 

Whether your home is located near the Highland Lighthouse, or way across the Cape, you can count on us to accommodate all your needs. Give us a call and start exploring your options today!