Seattle Companies Want to Drive Down Prohibitive ADU Costs

Legal barriers to accessory dwelling units may be disappearing in some places, but costs can still be prohibitive. Several companies are stepping forward with more affordable options.

1 minute read

November 25, 2019, 10:00 AM PST

By Philip Rojc @PhilipRojc


Accessory Dwelling Unit

Nicolás Boullosa / Flickr

In Seattle and elsewhere in the Pacific Northwest, ADU reform is moving forward at a decent clip. However, Natalie Bicknell writes, "adding a new dwelling unit, particularly if it is a detached accessory dwelling unit or DADU, is still an expensive and onerous process that can present insurmountable hurdles for many property owners."

Bicknell goes on, "An interesting fact about backyard cottages is that while they do tend to eventually rent for rates that are either at or below market value, in terms of square footage, backyard cottages are often the expensive type of housing to construct per square foot."

Why are DADUs so expensive? Because size often matters less than costs related to design, utility connection, construction, and permitting, which can drive prices into unworkable territory.

Bicknell goes on to discuss several Seattle-area companies offering to take care of those issues for potential ADU owners. According to one founder, several other tactics help reduce costs, including standardizing structures' corners and using raised foundations.

Wednesday, November 13, 2019 in The Urbanist

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Close-up of "Apartment for rent" sign in red text on black background in front of blurred building

Trump Administration Could Effectively End Housing Voucher Program

Federal officials are eyeing major cuts to the Section 8 program that helps millions of low-income households pay rent.

April 21, 2025 - Housing Wire

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

April 23, 2025 - Diana Ionescu

Ken Jennings stands in front of Snohomish County Community Transit bus.

Ken Jennings Launches Transit Web Series

The Jeopardy champ wants you to ride public transit.

April 20, 2025 - Streetsblog USA

View of Washington state capitol dome in Olympia, Washington at golden hour.

Washington Legislature Passes Rent Increase Cap

A bill that caps rent increases at 7 percent plus inflation is headed to the governor’s desk.

April 29 - Washington State Standard

Low view of Glendale Narrows section of Los Angeles River with concrete bottom and cloudy storm sky over head.

From Planning to Action: How LA County Is Rethinking Climate Resilience

Chief Sustainability Officer Rita Kampalath outlines the County’s shift from planning to implementation in its climate resilience efforts, emphasizing cross-departmental coordination, updated recovery strategies, and the need for flexible funding.

April 29 - The Planning Report

Grandparents sitting on bench with young girl and boy, girl holding ball and boy holding ukelele.

New Mexico Aging Department Commits to Helping Seniors Age ‘In Place’ and ‘Autonomously’ in New Draft Plan

As New Mexico’s population of seniors continues to grow, the state’s aging department is proposing expanded initiatives to help seniors maintain their autonomy while also supporting family caregivers.

April 29 - Source NM