ADU Construction on Seattle's Eastside, WA

“Eastside ADU builder” is a service-area phrase, not a permit type. The same builder may work across Lake Washington but use different plans and codes in each city.

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

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 state rules, but cities apply them through local codes, forms and reviews. Slopes, trees, critical areas, utilities and plan programs also differ. An old city handout may come before a 2025 law.

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

How does Bellevue differ?

Bellevue changed its housing rules in 2025 for attached and detached ADUs. The City says it is developing a DADU and cottage plan program in stages. That does not mean a plan catalog is ready now.

Check the zoning, lot limits, trees, critical areas, utilities and current filing path. 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 it as a faster, lower-cost path and limits the designer’s plan fee. The project still needs a site plan, property review, permit file and construction.

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’s home permit page covers new ADUs and garage conversions. An older guide describes attached and detached ADUs in home zones. Owners should still check the current code after the City’s 2025 updates.

Use the Redmond page to separate current adopted rules 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.
• work setup without blocking the main home.

These conditions can change the plan, foundation and total price. Put them in the site check brief before asking for a firm total.

Are pre-approved plans automatically cheaper?

They can reduce repeat design work when the program and lot fit. They do not remove the survey, site plan, foundation changes or energy records. Utility design, drainage, local fees and construction remain.

Compare the plan fee, allowed changes, code year, foundation, structure and site documents. Use the pre-approved versus custom guide to compare the full installed cost, not just the drawings.

How should Eastside costs be normalized?

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

• early site checks 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 repairs after the work.
• extra budget for surprises or exclusions.

An “affluent market” label does not price the work. The lot, plans and finish level control the quote.

How should an Eastside company be checked?

Check the legal builder in Washington L&I and ask for recent work in the same city. Ask who prepared the plans, filed them, answered City comments and 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, work, allowances, payment and written terms.

Prepare one Eastside bid package

Give every builder the same package. Include a survey or measured site plan, the city, chosen concept, rooms and finish list. Add utility assumptions, tree or critical-area details and owner-builder duties. Put a date on every document.

Ask each bidder to return a table of included work 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 repairs after the work. This makes two quotes comparable even when the businesses bundle services differently.

What should be confirmed before buying a plan?

First check that the plan owner allows use in the city and that the city accepts its review status. Then test the footprint, direction, access, foundation and allowed changes on the site. Add the energy and utility plans. Ask for the full list of site sheets and experts still needed.

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.

Open the current city sources

Use the official pages for Bellevue ADU reform, Kirkland housing and DADU resources, and Redmond residential permits. Select the page for the actual parcel and confirm current forms, plan status and site requirements with that city.