Accessory Dwelling Units (ADUs)


ADUs - Extra Space, Extra Cash - Property Management ...Accessory Dwelling Units (ADUs) are becoming increasingly popular as a way for communities to create more affordable rental options.

You may know these as backyard cottages, mother-in-laws, or granny flats. Whatever you call them, ADUs are one of the most immediate housing solutions available to us. By utilizing the existing space in either our backyard or perhaps in our garage, basement, or attic, we are providing necessary infill for our community to support itself.

ADUs are allowed throughout Jefferson County right now. HSN has compiled helpful resources to guide anyone through the process of getting starting their ADU project. We aim to make it easy for you to support workforce housing development here at home.

Local Rules

Jefferson County defines an ADU as, “an additional dwelling unit either in or added to an existing single family detached dwelling, or in a separate accessory structure on the same lot as the main structure, for use as a complete, independent living facility with provisions within the accessory dwelling unit for cooking, eating, sanitation and sleeping.”

The City of Port Townsend allows both the primary residence and ADU to be rented out, whereas everywhere else in Jefferson County, if you are building an ADU on a lot with an existing home, the owner of the single family home must occupy either the primary unit or the ADU if you plan to rent one out.

Learn more about design, permitting, and other ADU guidelines for the City of Port Townsend and Jefferson County.

Highlighting Local ADU Projects

Are You Considering an ADU?

HSN is committed to enabling more affordable housing in Jefferson County. One of the surest ways we can do that quickly is through utilizing ADUs.

If the answer is ‘yes’ to any of these following questions, we’d love to speak with you further.

  • Do you have land where a small, new additional dwelling unit might fit?
  • Do you have a basement, garage or other area where re-modelling might yield a rental unit?
  • Would you like to earn rental income while helping provide more affordable housing?
  • Do you have questions about financing, permitting, or construction that have held you back?
  • Do you want to explore your options now?

Additionally, HSN has produced the Permit Navigator informational video series with local builders and designers that walk the viewer through, step by step, the process of completing an ADU building permit.

How else can we support your ADU vision? Fill out the short form on this page with these guiding questions and we’ll reach out to start a conversation.

Build Options


Traditional on-site construction using dimensional lumber.

Commercial Examples

  • Most homes in Jefferson County!


Whole units are built off-site, then delivered and installed. Site work and permitting is still required, as is the interior finish work.

Commercial Examples


Building materials are cut and packaged off-site, and delivered with assembly instructions.

Commercial Examples

Local Advocacy Opportunities

  • ‘Pre-approved ADUs’ are units that have been accepted as well-designed and are permit-able by a municipaltities. This can expedite the ADU process for builders. Jefferson County and the City of Port Townsend are both considering following pre-approved models from Clallam County and the City of Seattle. 
  • The County is considering an update to its ADU policy that would allow for more small units per parcel. Contact Planning Commissioner Matt Sircely at to learn more.

Do you have a question about ADUs? HSN can help!

Accessory dwelling units (ADU) are a fast and effective workforce housing solution, and we have the resources to get your project started!