ADU Construction on Seattle's Eastside, WA

“Eastside ADU builder” is a service-area phrase, not a permit category. The same contractor may work across Lake Washington while filing different documents and responding to different codes in each city.

This hub compares early reader decisions. Use the individual city pages and live official sources for the property.

Bellevue, Kirkland and Redmond at a glance

Read the full guides for Bellevue, Kirkland and Redmond.

Why can’t one Eastside rule summary be used?

Washington HB 1337 set statewide requirements, but cities implement them through local code, forms and review. Local terrain, trees, critical areas, utilities and plan programs also differ. An old city handout may predate a 2025 ordinance.

For each property, record the live code or official page, checked date and any staff confirmation. Avoid relying on a provider article that collapses several cities into one table.

How does Bellevue differ?

Bellevue adopted middle-housing amendments in 2025 to address state requirements for attached and detached ADUs. The City says it is developing a pre-approved DADU and cottage plan program in phases. That is not the same as having a current catalogue ready for immediate use.

The project should confirm residential zone, lot constraints, tree and critical-area conditions, utilities and the current application route. Read the Bellevue page before accepting a “pre-approved” claim.

How does Kirkland differ?

Kirkland already offers a pre-approved DADU program. The City describes the plans as a faster and cheaper route and limits the plan royalty set by the designer. A selected plan still needs a site plan, property review, permit documents and construction scope.

Kirkland lots may also present slopes, lake or stream conditions, tree protection and access questions. Read the Kirkland page for the plan-fit checklist.

How does Redmond differ?

Redmond publishes a residential-permit page that includes adding an ADU and converting a garage to living space. An older user guide describes attached and detached ADUs across residential zones, but owners should check the current code after the City’s 2025 state-law update work.

Use the Redmond page to separate current adopted requirements from older explanatory documents.

What site work is common across the Eastside?

Each property is different, but recurring early checks include:

• side-yard or driveway access for excavation and deliveries;
• mature trees and root protection;
• slope, retaining walls and erosion control;
• critical areas, streams, wetlands or shorelines;
• water and sewer connection routes;
• electrical service and equipment placement;
• stormwater and roof drainage; and
• construction staging without blocking the main home.

These conditions can change plan orientation, foundation design and total price. Put them in the feasibility brief before requesting a firm construction total.

Are pre-approved plans automatically cheaper?

They can reduce repeated structural or building-plan work when the program and lot fit. They do not remove survey, site plan, foundation adaptation, energy documents, utility design, drainage, local fees or construction.

Compare the plan’s licence or royalty, allowed changes, code edition, foundation assumptions, structural scope and site documents. Use the pre-approved versus custom guide to measure the complete installed path rather than drawing price.

How should Eastside costs be normalized?

The ADU cost guide provides one category schedule. For an Eastside comparison, require every proposal to address:

• feasibility and survey;
• architecture, structural and energy documents;
• City permit and correction responses;
• demolition, access and site protection;
• foundation and building shell;
• power, water, sewer and stormwater;
• finishes and allowances;
• landscaping and property restoration; and
• contingency or exclusions.

An affluent-market price label does not establish the work. The lot and specification control the proposal.

How should an Eastside provider be checked?

Verify the legal entity in Washington L&I and request recent relevant projects in the same city. Ask who prepared and submitted the permit set, which staff handled corrections and whether the same entity completed construction.

Confirm actual service area and capacity for the address. A page listing every Eastside city is not project evidence. The builder comparison guide helps evaluate registration, project proof, scope, allowances, payment and written terms.

Prepare one Eastside bid package

Use the same package for every builder: current survey or measured site plan, jurisdiction confirmation, chosen concept, room and finish schedule, utility assumptions, tree or critical-area information and the desired responsibility split. Label every document with its date and revision.

Ask each bidder to return a scope matrix rather than only a total. The matrix should mark included, allowance, owner-direct and excluded work for design, City corrections, permit fees, demolition, foundation, utilities, drainage, finishes and restoration. This makes two proposals comparable even when the businesses bundle services differently.

What should be confirmed before buying a plan?

First confirm that the plan owner permits use in the city and that the city recognizes the claimed review status. Then test footprint, orientation, access, foundation assumptions, allowed changes, energy-code basis and utility layout against the property. Request the full list of site-specific sheets and consultants still required.

A plan purchase is useful only when it shortens the complete route. If substantial redesign or structural adaptation is likely, compare the total pre-approved path with a custom concept before committing.