Use calendar estimates only after defining the start and finish of each stage. Seattle review time can change. Site findings can change the design, and slow products can change the work order. The schedule should show duties and proof, not just dates.
Gate 1: confirm the site case
The first stage confirms the parcel, permit office, records and likely ADU type. Gather available plans and check access, buildings, slopes, trees and utilities. Decide whether the team needs a survey, utility locating or expert report.
This stage ends with a written site check finding, a list of open issues and a clear choice to proceed, revise or stop.
Gate 2: select the design route
Put the household goals in a project brief. Test the unit’s location and compare custom, repeat and pre-approved plans. Get an early cost range before moving forward, using the Seattle ADU cost guide to define what the range includes.
Close this gate with an approved concept, delivery strategy, named consultant team and design agreement. If an ADUniverse plan is selected, list all site-specific work that remains.
Gate 3: plan the technical quote
The team develops the site, building, structural, energy and system details. Utility routes and foundation plans should grow with the floor plan. Owner finish choices need due dates because they affect the plans and price.
Before filing, run a planning review and keep a dated drawing register. Incomplete internal planning often returns later as corrections or field changes.
Gate 4: submit and respond
Inside Seattle, the project follows the current SDCI process. Track intake, review, City comments, team replies and new filings. Other cities and King County use different steps. Their schedules should use their own current guidance.
Separate three clocks:
- time controlled by the reviewing bodies.
- time used by designers and consultants.
- time awaiting owner choices or payment.
This makes delays understandable and keeps an agency estimate from becoming an unsupported completion promise.
Gate 5: resolve commercial work
Once the plans are clear enough, give the same price set to qualified builders. Allow time for site visits, questions and quote review. Check references, L&I registration, insurance and the contract.
This stage ends with a signed contract, base budget and schedule tied to the issued plans. Do not rush builder checks because design review took longer than planned.
Gate 6: complete pre-start conditions
A permit may not be the only start condition. Confirm utility tasks, approved changes, later documents, notices, insurance and site access. Order slow products. State who calls inspections and keeps the site record.
Hold a preconstruction meeting to walk through logistics, protection of the occupied home, neighbor issues, communication and change authorization.
Gate 7: deliver the field work
A detached build often moves through site setup, digging, foundation and framing. Then come the outside shell, rough utilities, insulation, indoor work, fixtures and yard repairs. Conversions and attached units use a different order and may affect an occupied house.
Weather, inspections and hidden conditions can change the next few weeks. Ask the builder for a rolling schedule of choices, inspections and deliveries. Do not rely only on the first chart.
Gate 8: inspect, finish and document
Near the end, list unfinished or defective work and set repair dates. Keep inspections moving. Test the systems and collect product details, warranties, approved plans and inspection records.
Final payment and use should follow the contract and approval rules. A finished-looking unit does not prove that every permit condition is closed.
Build a schedule register
For each important event, record:
- planned date and latest forecast.
- the person or organization responsible.
- details required before it can start.
- the evidence that marks completion.
- the downstream work affected if it moves.
Update this register at regular project meetings. A schedule without owners and dependencies is only a wish list.
Protect the critical choices
Owners can reduce avoidable delay by setting choice deadlines for the ADU type, plan route, exterior appearance, principal equipment, windows, cabinets, tile and appliances. The team should explain which selections truly affect approval, rough work or ordering.
Avoid making every finish choice at the beginning. Sequence choices by consequence. Equally, do not leave products with long lead times until framing is complete.
Frequently asked questions
How long does a Seattle ADU take?
It depends on design, City review, utility work, builder schedules and site conditions. Ask for a property-specific schedule with clear assumptions. Do not rely on a marketing promise.
Can pricing happen during permit review?
Yes, if bidders receive a controlled document set and the owner expects updates after corrections. State how later revisions will be incorporated.
What often causes owner-controlled delay?
Late program changes, slow consultant appointments, unresolved selections, financing and contract choices can all matter. A choice schedule gives these items visibility.
Should a contractor guarantee the completion date?
Review the contract terms for the project. At minimum, understand start conditions, allowed delays, owner changes and notice rules. State how schedule updates will be shared.