Building an ADU in Bellingham 101

ADU kitchen

Accessory dwelling units (ADUs) have been a source of opinionated conversations in the Bellingham building community for the past few years, and for good reason. The Bellingham City Council recently approved all styles of ADUs in single family zones city-wide after a multi-year process of professional analysis, public comments, and planning committee meetings. Although this isn’t a sentiment shared by everyone in Bellingham, we have been in support of updating the ADU ordinance from the beginning. Here’s a quick primer on ADUs in Bellingham, why Chuckanut Builders is in support of them and things to consider if you’re contemplating adding an ADU to your property.

What is an ADU?

In general, an ADU is a small, self-contained residential unit on the same property as a single-family home. ADUs are often referred to as “mother-in-law apartments” or “granny flats.” These units have all of the basic facilities necessary for day-to-day living including a kitchen, sleeping area, bathroom and separate entrance, and can either be a separate unit within the home (like a basement), an addition attached to the home or a standalone structure on the lot, often in the backyard.

What is a DADU?

A DADU is an ADU that is detached from the main dwelling (DADU=Detached ADU). Prior to the spring of 2018, there were limits on in-home and attached ADUs in single-family neighborhoods. Additionally,  DADUs were not allowed. In addition, the impact fees where quite high, making their construction cost-prohibitive for most homeowners. The new ordinance allows DADUs and increases the number of allowable ADUs citywide. Furthermore, the city council is expected to approve a reduction of the impact and permit fees to make building ADUs and DADUs more affordable. Because of acronym overload, we, along with many folks, refer to ADUs and DADUs collectively as ADUs.

ADU compact bathroom

Why we’re in support of ADUs

We’re in support of ADUs for a handful of reasons. Urban sprawl is at the top of the list – it’s bad for our community, the environment and the residents of Bellingham. Building on the fringes requires that we use our limited resources to construct new roads and add infrastructure. It also increases traffic as people commute further to work, school and leisure activities, and forever alters the farmlands and working forests we rely on.

In addition, ADUs increase housing options at a time when Bellingham desperately needs them. ADUs can provide rental income for homeowners and affordable opportunities for renters looking to live in an established neighborhood. One concern we’ve heard over and over again is that adding ADUs will change the fabric of the neighborhood. Folks are concerned that developers will purchase lots and build ADUs on them. One requirement of the new ordinance is that one of the dwellings be occupied by the property owner, ensuring that neighborhoods won’t be over-developed. This requirement will support diverse core neighborhoods that are vibrant and walkable.   

Things to consider if you’d like to build an ADU

Below is a condensed list of site requirements for homeowners thinking about building an ADU on their property. For more information check out the city’s infill housing regulations.   

  • There is a limit of one DADU per lot.
  • An owner must occupy on of the units. 
  • There is a size limit of 800 square feet or 66 percent of the main structure, whichever is smaller.
  • The lot must have alley access, access to more than one public street, or must be greater than 5,000 square feet.
  • There must be a separation of 6 or more feet between the main residence and the DADU.
  • DADUs must have a parking space. Homeowners can add a street curb cut to accommodate parking, which would eliminate on-street parking.
  • The DADU and primary residence should have similar design features.

What’s next?

More ADUs, we hope! We have promoted infill for years. The updated ADU ordinance provides more options for helping to make that a reality. If you have questions about building an ADU contact us. We’re happy to schedule a site visit, recommend a designer, and do our part to increase housing options in Bellingham.