Intro call
A quick conversation about your lot and goals.
Seattle & the Eastside
Unlock your lot's hidden value.
Infill ADU designs, permits, and builds custom ADUs across Seattle and the Eastside — every home drawn for its lot, from first feasibility check to final inspection.
One clear path
How it works
From the first conversation through warranty, every phase stays connected — with a clear scope, timing, and next step.
Typical all-in investment: $280,000–$400,000
Every lot is different — your feasibility study pins down your exact number before you commit to anything.
Feasibility study
Credited toward your design costs if you move forward with us.
Custom design
Drawn for your lot's zoning, setbacks, trees, utilities, and goals.
Typical third-party professional costsArchitect: $8,000–$12,000Structural engineer: $3,000–$5,000Market reference only for licensed professionals on the project — these are not Infill ADU fees. Final costs vary by scope.
Permitting
We handle the full permit process. Timing depends on the jurisdiction.
Construction
Your custom ADU is built by one accountable team from site work through final inspection.
Warranty
We stand behind the work after the keys are handed over.
Start with certainty
ADU Feasibility Study
Before you spend thousands on design and permitting, know exactly what your lot can do.
$649 one-time
Delivered within 3 business days
If you build with us, the $649 comes off your design costs — the study is effectively free.
What's included
- Zoning & lot capacity reviewAllowed size, height, setbacks, and parking requirements.
- Utility & site assessmentWater, sewer, power, and lot access — with hidden site costs flagged early.
- Realistic all-in budget rangeA property-specific planning range, not a generic square-foot number.
- Rental income & ROI sketchAn early look at how the project may perform against your goals.
- Clear recommendationA straightforward go / no-go view with practical next steps.
More from the space you own
Why build an ADU
Rental income
A new revenue stream from space you already own.
Flexible housing for family
Room for parents, kids, or guests, close but independent.
Added property value
An ADU makes your whole property worth more.
Services
One team, start to finish.
From first feasibility check to final inspection — one team for your entire ADU project.
01
Free ADU feasibility assessment
Lot analysis, zoning check, and buildable options for your property. Know what's possible before you spend a dollar.
02
Custom design
Every attached or detached ADU is drawn for your property — we do not sell a catalog of pre-designed models.
03
Permitting
We manage the entire permit process with your city, start to finish.
04
Construction
True design-build: one team from plans to keys, one point of accountability.
Why custom?
Your ADU should respond to your lot's zoning, setbacks, trees, utilities, access, and goals — not force a one-size box onto your property.
About
Built around ADUs.
Infill ADU is a Seattle company that specializes in ADUs — with over 10 years of experience and over 100 units completed. We handle everything from design to permits to construction, so you get one team accountable from the first feasibility check to final inspection.
Service areas
BellevueKirklandRedmondIssaquahWoodinvilleSeattle
Our Work
Dirt to done.
A project takes shape one exacting phase at a time. Select any image for a closer look.
Good to know
Questions, answered clearly.
Every lot is different. These are the practical starting points we use to frame an ADU project.
Can every property support an ADU?
Not always. Zoning is only the first check. Lot shape, setbacks, access, trees, utilities, drainage, and other site conditions can all affect what is practical to build.
Do you build both attached and detached ADUs?
Yes. We design and build attached ADUs, detached backyard homes, and property-specific layouts shaped around your lot and goals.
Can Infill ADU handle the permits too?
Yes. Our design-build process includes permit preparation and coordination with the city, so the same team stays accountable through design, approval, and construction.
What happens after I request an assessment?
We start with your property address and goals, review the basic site and zoning considerations, then follow up to discuss the most useful next step.
Curious what your lot can hold?
Get a free lot assessmentContact
Start with your lot.
Tell us what you're considering. We'll begin with a free look at your property's ADU potential.
- Basic zoning and lot-fit review
- Early access, utility, and site considerations
- A clear recommendation for your next step
425-426-9999
info@infilladu.com
Service areasBellevue, Kirkland, Redmond, Issaquah, Woodinville, Seattle