Your plans are finally with the city, and the portal shows a list of reviews you have never heard of. That list is normal. In a Seattle DADU review, SDCI sends one plan set to several teams, each checking a different code, and most projects go through at least one round of corrections. A DADU, or detached accessory dwelling unit, is a separate home on the same lot as a house.

Details below reflect official Seattle pages checked in October 2026. Confirm with city staff for your property.

How Does the Process Start?

Everything begins in the Seattle Services Portal. According to SDCI Tip 116B, you or your designer first submit a site plan with a Building and Land Use Pre‑Application. SDCI confirms the legal description and address, assigns a record number and tells you if a pre‑application site visit is needed.

Next comes an intake appointment, where the full plan set is uploaded. The tip warned that the next opening could be two to four months out when it was written, so check current availability. Keep the record number handy, since every later step uses it. It follows a format ending in CN for construction permits.

Zoning and Land Use Checks

Zoning review asks whether the cottage fits the lot. Reviewers compare the plans with the Land Use Code for setbacks, height, lot coverage, unit size and the number of units.

The guides on Seattle ADU setbacks and lot coverage explain what gets measured. Tree rules and critical area rules can add separate review on some sites.

The site plan also carries legal details, such as the full legal description and any recorded easements. If an access or utility easement crosses your yard, the reviewer will want it drawn, and the post on DADU easement restrictions explains why it can move the footprint.

Structure and Building Code

Structural review looks at how the building stands up and resists wind and earthquakes. Reviewers check foundations, framing, beams and bracing against the Seattle Residential Code.

Tip 116B asks for full structural plans for a new building, including framing plans, foundation plans and sections. A design outside the code’s prescriptive bracing rules needs engineered calculations, and some sites need a soils report.

Energy and Drainage

Energy review checks insulation, windows, doors and heating equipment against the Seattle Energy Code. Tip 116B lists energy calculations among the application documents, so plan for them from the start.

Drainage review follows the Stormwater Code. Once a project adds or replaces enough hard surface, the plans need drainage and construction stormwater sheets. Seattle Public Utilities also checks water and sewer capacity during the same permit.

On a tight lot, drainage can drive the design. A cottage plus a new path and patio can push hard surface past the threshold, so ask your designer to total it early.

Which Life Safety Items Do Reviewers Look For?

Life safety rules protect the people who will live in the cottage. Tip 116B lists several that apply to every DADU.

• Smoke detectors and carbon monoxide alarms.
• An escape window or door in each sleeping room, with at least 5.7 square feet of clear opening.
• A finished sill no more than 44 inches above the floor.
• Heating controls separate from those in the main house.

Showing these clearly on the plans helps the Seattle DADU review move without extra questions.

A Hypothetical Ravenna Submittal

Picture an invented Ravenna lot with a flat yard, a 1920s house and an alley along the back. The owner plans a one bedroom cottage near the alley for her mother. Her designer uploads a complete set, but one elevation omits a window that the floor plan shows.

Zoning and energy reviews pass. The structural reviewer asks for a bracing calculation, and the building reviewer flags the window mismatch. Both items go back in one response, and the second cycle clears.

Small gaps like a missing window happen on many projects. They cost a full cycle, which is why a careful sheet by sheet check before upload pays off.

How Do Correction Cycles Work?

SDCI’s page on responding to review comments explains the rules. Every review must finish and the status must read Corrections Required before you can reply. The designer answers each comment, clouds the changes and uploads a complete plan set.

SDCI lists a target of two weeks to review corrected plans. Uploading single sheets or skipping responses can delay the review, and the city may charge a penalty fee.

If you make changes the reviewer did not ask for, describe them in the response too. Significant changes can bring added fees, so talk with your designer before you redesign mid review.

Common Review Surprises

• Waiting for the slowest review before any reply is allowed.
• Sheets that disagree with each other.
• Engineering needed for an open floor plan or large windows.
• Tree or drainage review added after intake.
• Voluntary design changes that need their own explanation.

Frequently Asked Questions

Does submitting plans mean I can build?

No. You can build only after SDCI issues the permit. Tip 116B notes the permit and approved plans then appear in your portal account.

Is there a public comment period?

No. Tip 116B states there is no public comment period or appeal for a DADU construction permit. Land use reviews on unusual sites can differ.

How can I see where my review stands?

The portal shows each review’s status. SDCI’s Construction Permit Timeline tool also shows when the file sat with the city and when it sat with you.

Before You Upload

• Check that every sheet matches the others.
• Confirm life safety items appear on the plans.
• Gather energy and structural calculations.
• Name one person to answer every comment.
• Total the new and replaced hard surface.

Plan review is easier to follow when you know which team holds the file. Submit a complete, consistent set and answer every comment in one pass. The overview of DADU permit requirements lists the trade permits that follow, and the permits and approvals section covers each stage.