QA_INDEX / EXPERT_ANSWERS
ADU Questions, Answered
Direct answers from licensed Puget Sound ADU builders. No fluff. No SEO filler. Cost numbers, permit timelines, and zoning specifics are updated quarterly from real projects.
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Permits
7 answers- SeattleHow long does an ADU permit really take in Seattle?
- SeattleAre Seattle’s pre-approved DADU plans actually faster?
- SeattleDo I need a separate side-sewer for a Seattle DADU?
- BellevueIs it easier to build an ADU in Bellevue than Seattle?
- SeattleDoes Seattle charge ADU impact fees?
- Puget SoundDoes my basement need egress windows for a legal AADU?
- SeattleHow does Seattle tree retention affect my ADU project?
Zoning
7 answers- SeattleCan I really build two ADUs on a single lot in Seattle?
- SeattleDo I have to live on the property to build an ADU in Seattle?
- SeattleWhat are the setback rules for a Seattle DADU?
- KirklandWhat are the current ADU rules in Kirkland?
- RedmondCan I build a DADU in Redmond?
- SeattleCan I build a DADU on a 3,200 sqft Seattle lot?
- SeattleCan I run a Seattle ADU as a short-term rental (Airbnb)?
Cost & ROI
8 answers- SeattleHow much does a DADU really cost in Seattle in 2026?
- Puget SoundDADU vs AADU — which makes more financial sense?
- SeattleHow much can I rent a Seattle DADU for in 2026?
- SeattleWhat does it cost to convert a garage into an AADU in Seattle?
- SeattleHow much value does an ADU add to a Seattle home?
- SeattleHow much should I budget for ADU design and architecture?
- SeattleHow much will my property taxes go up after an ADU?
- Puget SoundIs an ADU cheaper than just adding onto my house?
Financing
1 answersBuild Process
7 answers- Puget SoundHow long does it take to actually build an ADU once permits are issued?
- Puget SoundWhat foundation should I use for a DADU?
- Puget SoundDo I need to upgrade my electrical service for an ADU?
- SeattleWhat are the most expensive mistakes Seattle homeowners make on ADUs?
- SeattleHow do I find a trustworthy ADU builder in Seattle?
- SeattleShould I install separate utility meters for my Seattle ADU?
- Puget SoundHow do I soundproof an attached AADU from the main house?
Frequently asked
What is this Q&A board page for?
This Q&A board page is one node in our reference library for Puget Sound ADU owners and prospective builders. Every page is written to be useful on its own and to link cleanly to the next decision you need to make — feasibility, financing, permit, build, or hold. If you can't find what you need, use the contact form or book a free scoping call.
How does this page connect to my actual project?
Information on this page is anchored in current 2026 WA code (RCW 36.70A.681 / HB 1337 statewide preemption, IECC residential energy code, local AHJ implementing ordinances) and current Golden State internal data (bid archive, permit logs, rent comps). The next concrete step is almost always a feasibility study — $1,500, two weeks, credited to your build contract.
Where do I go from here?
Three good next stops: (1) the ROI calculator if you're evaluating whether the math works on your lot; (2) the permit timeline page for current AHJ medians in your city; (3) the contact form to book a free 20-minute scoping call. Every page in this library cross-links the most relevant next pages at the bottom — follow the trail that matches your decision stage.