Menu
An Accessory Dwelling Unit (ADU) is a secondary housing unit located on the same lot as a single-family home. While the term “accessory dwelling unit” may sound technical, it’s the widely accepted term used nationwide to describe this form of housing. To simplify things, people commonly refer to these units as ADUs.
Unlike other housing types, ADUs are unique in that they do not follow a specific structural blueprint. Instead, ADUs come in various forms, and understanding them requires thinking beyond a single image or concept. While it’s natural to want to picture exactly what an ADU looks like, these units can take many different shapes. By exploring the various types of ADUs, you can better understand the flexibility of these living spaces.
ADUs can be constructed in several different ways, each offering distinct design advantages. The following are the most common types of ADUs:
These ADUs are separate structures from the main house and are often called backyard cottages, granny flats, laneway houses, or DADUs (Detached Accessory Dwelling Units) depending on local regulations. Typically built in the backyard or on the side of a home, detached ADUs provide a private space while still being part of the primary property.
In this case, an existing garage is transformed into a living space. It’s a popular choice for homeowners who want to maximize their property without adding new structures. Garage conversions are cost-effective and make use of otherwise underutilized space.
Often referred to as garage apartments or carriage houses, these ADUs are built above a garage or workshop. This type of ADU offers additional living space without increasing the building footprint, making it an efficient option for smaller lots.
These ADUs are physically connected to the main house, sharing walls and benefiting from the existing infrastructure of the primary home. Since they’re integrated into the main structure, bump-out ADUs offer easy access to utilities like electricity, water, and sewer systems.
A basement conversion involves transforming a home’s basement into a separate dwelling unit. Known by names like in-law suites, secondary suites, or English basements, this type of ADU is particularly common in cities where space is at a premium.
This type of ADU is created by converting part of the primary house, excluding the basement, into a separate living space. For example, a homeowner may convert an attic or a large unused room into an internal ADU.
While ADUs can vary widely in design and structure, they share some common traits that distinguish them from other types of housing:
Despite these differences, ADUs are a distinct and rapidly growing category of housing, especially in urban areas.
Surveys and studies have shown that informal ADUs account for 10-20% of housing in major metropolitan areas like Los Angeles, San Francisco, and Vancouver. This suggests that millions of informal ADUs exist across the U.S., indicating a high demand for these units, even if many are not officially recognized.
Certain cities have embraced ADUs as a way to provide additional housing without expanding infrastructure. Portland, Oregon, is a leader in this type of housing, with over a decade of experience in streamlining ADU permits. Vancouver, BC, has similarly embraced ADUs, and Austin, Texas, saw a surge in ADU development after zoning changes in 2015.
A major driver behind ADU demand is the changing size of households in the U.S. Most households today consist of 1-2 people, yet the majority of available housing is designed for larger families. ADUs offer a more appropriate living space for these smaller households, which now make up over 60% of the population. This mismatch between household size and available housing stock is creating increased demand for flexible living options like ADUs.
Municipalities are beginning to recognize the many benefits ADUs offer, including:
Despite their benefits, there are several obstacles to the widespread adoption of ADUs. In many cities, regulatory hurdles and zoning restrictions make it difficult for homeowners to get permits for ADU construction. However, states like California have made legislative changes to encourage more ADU development, signaling a shift towards making ADUs more mainstream.
While ADUs won’t solve all housing challenges, they offer a flexible, affordable, and environmentally friendly option for homeowners. The most common motivations for building ADUs include generating rental income and creating space for multigenerational living. As more cities adopt ADU-friendly regulations, these units are likely to play an increasingly important role in the housing market.
If you’re interested in building an ADU, it’s essential to understand the regulations in your area and the step-by-step process involved. ADU development requires careful planning, from finding a designer and ADU builders to navigating zoning laws, but the long-term benefits can be substantial for homeowners and communities alike.
Looking for a Professional, Reliable & Affordable ADU Contractor?
Your search is over!
Contact us now for a free onsite consultation!
