ADUs & DADUs in Snohomish
The Svensen Timber Collection — productized, priced, ready.
Snohomish is defined by its historic downtown and riverfront — a town that values heritage and craftsmanship. Its larger lots suit timber-frame custom homes, additions, and the kind of build that looks like it belongs.
Washington's ADU law changes turned the backyard into the most valuable square footage on many lots. Svensen builds detached (DADU) and attached (ADU) dwellings that add real, rentable, livable space — with the same timber craft as our custom homes.
To make the decision simple, we productized it. The Svensen Timber Collection is a set of fixed models with tiered pricing, so you know what you are getting and what it costs before the first drawing.
The Svensen Timber Collection
- Timber 800 — efficient one-bed / studio footprint
- Timber 1000 — one to two bedrooms, full kitchen
- Timber 1200 — two-plus bedrooms, premium finish
- Detached (DADU) and attached (ADU) configurations
- Permit and code navigation under current WA ADU law
- Site work, utility connections, and finish
City of Snohomish, not Snohomish County
This is the distinction that sends more homeowners down the wrong path than any other in our service area. Snohomish is both a city and a county, and the rules are not the same. If your parcel sits inside the city limits, the Snohomish Municipal Code governs, and the county’s ADU bulletins may not apply to you at all. Establish which one you are in before anything else.
The city adopted new accessory dwelling unit regulations in 2024, now sitting in the municipal code as its own chapter, and is revising them again to align with state condominium law. The provision worth knowing is on utilities: a detached unit needs its own water and sewer connection, and connection fees are assessed at 50 percent of the adopted fee for the meter. An attached unit may share connections with the main house unless you intend to sell it independently later.
In unincorporated Snohomish County the picture is different again. Floor area is capped at 1,200 square feet excluding garages, porches, unheated storage and unfinished basements, and applicants must document both potable water of adequate flow and that the septic system can carry the extra load. In rural and resource zones a detached unit has to share the driveway with the house.
- Jurisdiction first
- Inside city limits the Snohomish Municipal Code governs. Outside, the county code does. Confirm before you design.
- City: detached units
- Require their own water and sewer connection.
- City: connection fees
- Assessed at 50% of the adopted fee for the meter.
- City: attached units
- May share connections with the principal unit, unless proposed for independent sale.
- City: placement
- No detached unit may be placed in the front setback.
- County: size
- Up to 1,200 sq ft, excluding garages, porches, unheated storage and unfinished basements.
- County: septic and water
- Documentation required that water is potable with adequate flow and that the septic system can handle the load. Worth resolving before paying for plans.
Source: Snohomish County Code 30.28.010, verified September 2026. Codes and fee schedules change. Confirm current requirements with the city before relying on this.
Because we mill and engineer in-house, a productized ADU does not mean a cheap one. The Timber Collection ships with real exposed timber that a typical modular or panelized ADU cannot offer at the price.
How the supply chain worksTiered, transparent pricing
Timber 800 / 1000 / 1200 are offered as priced tiers. Pick a model, confirm your site, and we give you a number — no mystery, no open-ended bid. (Current tier pricing available on request.)
From idea to backyard build
Pick a model
Choose the Timber 800, 1000, or 1200 based on your goals and lot.
Confirm the site
We assess setbacks, utilities, and access, and confirm your build is permittable.
Permit & prepare
We handle the ADU permit path and prep the site.
Build & finish
Your unit is built, connected, and finished to the Collection standard.
ADUs & DADUs in Snohomish: FAQ
Can I build an ADU or DADU in Snohomish?
In most cases, yes. Washington’s 2024–2025 ADU law changes (HB 1337) and Snohomish County’s Ordinance 25-014 expanded ADU rights, allowing up to two units on many lots. We confirm what your specific Snohomish lot allows during feasibility.
How much does an ADU cost in Snohomish?
Detached ADUs in the Puget Sound typically run roughly $250K–$450K all-in as of 2025. Our Svensen Timber Collection (Timber 800, 1000, 1200) is offered as fixed tiers so you get a clear Snohomish number up front instead of an open-ended bid.
How big can my ADU be in Snohomish?
Most Washington jurisdictions allow ADUs in the 800–1,200 sq ft range, which is exactly why our Timber Collection comes in 800, 1000, and 1200 — sized to the rules and ready for your Snohomish backyard.
Am I in the city of Snohomish or Snohomish County?
It matters more than almost anything else, and plenty of people get it wrong. Snohomish is both a city and a county, and they have separate codes. Inside city limits the municipal code governs and the county bulletins may not apply. Outside, the county rules do. Confirming jurisdiction is genuinely the first step, before design and before spending money on plans.
Will I need a separate water and sewer connection?
For a detached unit inside the city, yes. Connection fees are assessed at 50 percent of the adopted fee for the meter, which is a meaningful discount. An attached unit can share connections with the main house, unless you want to keep the option of selling it independently later, in which case it needs its own.
I am on septic. What do I need to prove?
That the existing or proposed system can handle the additional load, and that your water supply is potable with adequate flow. In the county this is documented as part of the application. It is worth resolving before you hire a designer, because a septic constraint can change the size or siting of the whole project.
Can I sell the ADU separately later?
The city is revising its accessory dwelling unit regulations to align with state condominium law, and independent sale is contemplated. If that is part of your thinking, say so at design stage. It affects how utilities are run from the start, and retrofitting separate services is far more expensive than planning for them.
ADUs & DADUs nearby
Let’s build something that outlasts the mortgage.
Tell us about your project. We’ll tell you what’s buildable, what it costs, and how the supply chain works in your favor.