AADUs, DADUs, and What You Need to Know About Council Bill 119544

On July 1, Seattle legislation unanimously passed a bill proposed by Councilman Mike O’Brien concerning the construction of backyard cottages (detached accessory dwelling units, or DADUs) and basement units (attached accessory dwelling units, or AADUs) on single-family property. This legislation, Council Bill 119544, aims to remove barriers that previously made constructing these units difficult, and create a boost in affordable housing in the Seattle metro area. Here’s what to know about DADUS, AADUs, and Council Bill 119544.

What Are AADUs and DADUs?

Attached accessory dwelling units are any self-contained unit connected to the property’s main house. For example, if you turn your basement or garage into its own unit with a bathroom, kitchen, and entrance, it would be an AADU.

Detached accessory dwelling units, sometimes known as mother-in-law units or backyard cottages, are any self-contained unit not attached to the main house, but built on a different area of the main property.

What Are the Benefits of AADUs and DADUs?

The advantages of building a backyard cottage or converting a basement unit into an AADU range from environmental benefits to financial gains. Here are a few.

Passive Income Opportunities

Earn extra income year-round by renting out your DADU or AADU with vacation rental services such as AirBnB or renting out longer-term using Craigslist. This is especially easy if you live in a big city or near a tourist attraction. In many cases, it is worth doing a cash-out refinance to fund the addition and bring in the extra income.

Close Care and Accessibility for Family

If you live with an elderly or ill parent or grandparent, providing them with their own unit on your property will keep them close by while retaining their independence. A DADU or AADU might also be a perfect option for a live-in nanny or housekeeper.

Eco-Friendly Advantages

AADUs and DADUs are low-impact, smaller units that use less resources and require less energy and utilities to heat and cool than the average single-family home.

Guidelines of Council Bill 119544

This bill will not only make it easier for homeowners to build AADUs and DADUs on their properties, but will also create more affordable housing options in Seattle neighborhoods. O’Brien states that if just 5% of eligible single-family properties build AADUs, it would create approximately 4,000 new housing units, financially supporting lower- and middle-income homeowners and providing more housing opportunities to lower-income renters simultaneously. 

Here are some guidelines of this new legislation:

  • Properties now only need to be 3,200 square feet to qualify to construct a DADU on their lot, instead of the previous 4,000 square feet minimum, allowing smaller homes to take advantage of the opportunity.
  • DADUs can be up to 1,000 square feet, larger than the previous 800 square feet maximum and allowing roomier housing for renters. According to a 2018 study, the average one-bedroom apartment in Seattle is a mere 711 square feet, the smallest in the country. Legislation also increases height limits by 1 to 3 feet.
  • This new bill will allow two accessory dwelling units on one property: either two that are attached, or one that is attached and one that is detached if the second AADU meets the city’s green building standards or is affordable to households at or below 80% of the neighborhood median income.
  • Design and construction flexibility is allowed in order to preserve existing trees and wildlife, as well as flexibility for green building strategies.
  • Finally, the new DADU and AADU legislation will require annual reporting on the production and inspection provided by the Office of Planning & Community Development, as well as the Seattle Department of Construction & Inspections, to begin within three years of construction.

If you have any questions about this new legislation or are interested in building a detached (or attached) accessory dwelling unit on your property, contact Vertical Construction today and let’s get started!

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