Condoizing a DADU in Seattle generally follows six steps: completing construction, commissioning a licensed survey, drafting a condominium declaration, forming a homeowners association, looping in your lender if there’s an existing mortgage, and recording everything with King County. Once that’s recorded, the county retires the original parcel number and issues each unit its own separate tax parcel — the point at which your DADU legally becomes its own sellable property.
What Condoization Actually Does (Quick Recap)
As a quick refresher: the land under your lot stays jointly held the whole time. What condoization actually creates is two independently titled structures — your house and your DADU — sitting on that shared land, managed through a condominium association rather than a traditional two-lot split. A true subdivision is the mechanism that divides the land itself, and it typically needs more lot area than most existing Seattle DADU properties have to work with.
With that context out of the way, here’s what the process actually looks like in practice.
Step 1 — Confirm Your DADU Is Eligible
Condoization applies to a real, permitted structure — not a plan on paper. In most cases, you’ll want your DADU fully built and holding a Certificate of Occupancy before you start the condo process, though some attorneys can advise on recording a declaration earlier in specific situations. This is worth confirming with a condo attorney directly, since it varies by project.
Before you spend money on a survey and legal work, it’s also worth taking advantage of SDCI’s pre-application coaching sessions. These let you flag potential issues early — unpermitted work from a previous owner, setback questions, or anything else that could complicate the process — before you’ve committed real budget to it. Older, informally built or unpermitted structures are the most common reason a condoization plan stalls partway through.
Step 2 — Commission a Licensed Survey (Condominium Map)
A licensed surveyor prepares the condominium map (sometimes called a condo plat) that documents the physical layout of both structures. This map defines:
- The exact boundaries of each unit
- Shared elements — driveways, utility easements, shared access
- Limited common elements — areas like a patio or parking spot assigned for one unit’s exclusive use, even though they’re technically part of the shared property
This document matters more than it might seem. It’s what legally establishes what a future buyer of either unit is actually purchasing, and what they’ll be responsible for maintaining jointly versus independently. Errors or vague boundaries here tend to surface later as disputes between owners, so accuracy at this stage is worth paying for.
Step 3 — Draft the Condominium Declaration
This is the core legal document, drafted by an attorney under Washington’s Condominium Property Act. The declaration is what actually creates the condominium — nothing is legally separated until this document exists and is recorded. It defines:
- Ownership shares for each unit
- The legal description and boundaries of each unit
- Use restrictions
- How maintenance responsibilities are divided between what’s owned individually and what’s shared
Because this document governs how the two units relate to each other going forward — including if one unit is later sold to a third party — it’s worth working with an attorney who has specific experience with small residential condo conversions, not just general real estate law.
Step 4 — Form the Homeowners Association (HOA)
Washington law requires a condominium — even a two-unit one — to have a homeowners association, formally established as a nonprofit corporation. That sounds heavier than it usually is in practice. For a two-unit Seattle DADU condo, the HOA typically doesn’t need complex management: its main functions are holding shared insurance, maintaining a modest reserve fund for common-element upkeep, and providing a formal structure for the two owners to make joint decisions when needed.
If you plan to sell the DADU to someone outside your family, both parties need to understand their obligations under the HOA’s governing documents before closing — this becomes part of what a buyer’s lender will review during financing.
Step 5 — Loop In Your Lender (If There’s an Existing Mortgage)
If there’s an existing mortgage on the property, the lender has a financial interest in the property as a single, whole asset — and a condominium declaration changes that. Most lenders will need to review and consent to the conversion, sometimes requiring a subordination agreement, before the declaration can be recorded.
This step is worth starting early rather than treating as a formality at the end. Lender review can move slower than the rest of the process, and it’s one of the more common places a condoization timeline stretches longer than expected.
Step 6 — Record Everything With King County
Once the declaration, survey/condo map, and HOA documents are finalized, they’re submitted to the King County Recorder’s Office, either in person or by mail, along with the applicable recording fees. This is the step that makes everything official.
After recording, King County retires the original single parcel number for the property and issues a separate tax parcel number for each unit. That’s the practical, legal marker of the whole process: from that point forward, the DADU exists as its own distinct property that can be independently financed, titled, and sold — separate from the main house.
How Long Does DADU Condoization Take?
There’s no single fixed timeline, because the process involves several independent parties — your attorney, your surveyor, the county, and potentially your lender — each working at their own pace. As a rough point of reference, the underlying construction permitting process for an ADU or DADU alone commonly runs anywhere from a few months to closer to a year depending on the jurisdiction and project complexity, and that’s before the condo-specific steps even begin. Declaration drafting, HOA formation, lender review, and recording each add their own time on top of that.
The honest answer is to get a specific estimate from your attorney and surveyor once your project is underway, rather than assuming a fixed number going in — and to build a buffer into any timeline you’re planning around, especially if a sale depends on it.
This is exactly why financing a DADU you intend to sell should account for delays in this process, not just construction time. See our guide on financing a build-to-sell DADU for how to structure a loan with that buffer in mind.
FAQ
How do you condoize a DADU in Seattle? The process runs through six general steps: confirm the DADU is a completed, permitted structure; commission a licensed survey; have an attorney draft a condominium declaration; form a homeowners association; get lender consent if there’s an existing mortgage; and record everything with King County. The county then issues a separate parcel number for each unit.
What does it mean to “convert a DADU to a condo”? It means legally separating ownership of the main house and the DADU into two independently titled units, while the underlying land stays under shared ownership through a condominium association. It’s a structural ownership change, not a physical change to the property.
What is the “DADU title split process”? “Title split” is commonly used to describe condoization in casual conversation, though it’s not a literal division of the land. The DADU and the main house each get their own title through the condominium declaration, while the lot itself remains jointly owned.
How long does DADU condoization take? It varies by property and jurisdiction, since it depends on multiple independent parties — attorney, surveyor, county recording, and potentially your lender. Getting a specific timeline estimate from your attorney once your project is underway is more reliable than relying on a general average.
Is DADU condoization the same as a lot subdivision through Seattle SDCI? No. Condoization separates ownership of the structures while the land stays shared through a condo association; a lot subdivision actually splits the parcel into separate legal lots with independent land titles. Most existing Seattle DADU properties use condoization because their lots don’t meet subdivision requirements — see our guide on selling a DADU separately for the full comparison.
How do I get a separate parcel number for my ADU or DADU? A separate parcel number is issued automatically by King County once your condominium declaration, survey, and HOA documents are recorded with the Recorder’s Office. It’s not something you apply for directly — it’s the outcome of completing the recording step.
