ADUs & DADUs in Arlington
The Svensen Timber Collection — productized, priced, ready.
Arlington is home to Washington Timber Company — our sawmill. When we say we mill our own Douglas Fir, this is where it happens. No town makes the Svensen vertical-integration story more literal: the timber in your build started a few miles from your lot.
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
More is possible on an Arlington lot than most owners expect
Washington changed what cities must allow on residential lots, and the result is a good deal more generous than the rules many homeowners remember. A lot can now carry two accessory dwelling units, owner occupancy cannot be required, and a city cannot cap an accessory unit below a thousand square feet.
Requirements do vary by address, and Arlington has its own submittal process on top of the state framework. We confirm the current standards with the city for your specific parcel before anything gets drawn, so the design is built around what is actually permitted today rather than what was permitted a few years ago.
For an Arlington project there is one more advantage worth knowing. Our sawmill is here, so the material for a timber-forward accessory unit is milled a few miles from your lot.
- Units per lot
- Two accessory units, attached, detached, or one of each.
- Owner occupancy
- Cannot be required for the principal unit or an accessory unit.
- Size
- A city cannot set a maximum gross floor area below 1,000 sq ft.
- Height
- Roof height limits below 24 feet are not permitted, unless the principal unit is held below that.
- Design
- Requirements for an accessory unit cannot be more restrictive than those applied to the principal dwelling.
- Your address
- We confirm current requirements with the city before design, so nothing is drawn against outdated assumptions.
Source: RCW 36.70A.681, 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 Arlington: FAQ
Can I build an ADU or DADU in Arlington?
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 Arlington lot allows during feasibility.
How much does an ADU cost in Arlington?
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 Arlington number up front instead of an open-ended bid.
How big can my ADU be in Arlington?
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 Arlington backyard.
How many accessory units can I put on an Arlington lot?
Two, under the current state framework, attached or detached or one of each. Requirements do vary by address and the details get refined over time, so we confirm what applies to your specific parcel with the city before anything is designed. That is a short conversation and it saves redrawing later.
Does the ADU have to match my house?
It does not have to be held to a tougher standard than the main house. Most owners want the two to sit well together regardless, and that is usually the better outcome for resale as well as for how the property feels. We will show you options that read as intentional rather than bolted on.
Does having the mill in Arlington change anything for me?
For a timber-forward build, yes. Washington Timber Company runs here, so material comes from a few miles away rather than a supplier’s catalogue. That mostly shows up in schedule: a member that needs resizing is a conversation rather than a reorder and a three-week wait.
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.