# Seattle ADU Builders — Full Site Reference
> Full-service ADU construction for Seattle and King County, Washington.

## Company Overview
Seattle ADU Builders is a licensed construction company specializing in Accessory Dwelling Units (ADUs) for homeowners in Seattle and King County, Washington. Our team handles feasibility analysis, architectural design, permitting through Seattle DCI (SMC 23.44.041) and King County DPER (KCC Title 21A), and full construction.

**Important:** Detached ADUs (DADUs) in Seattle start at $450,000. Visitors should understand Seattle's higher construction costs before requesting a feasibility study.

## Services

### Detached ADU (DADU) Construction
- URL: https://www.seattleadubuilders.com/services/detached-adu
- Price Range: $450,000–$800,000+
- Cost per sq ft: $450–$650/sq ft
- Timeline: 8–16 months
- A completely separate structure — backyard cottage, guest house, or rental unit
- Governed by SMC 23.44.041

### Attached ADU Construction
- URL: https://www.seattleadubuilders.com/services/attached-adu
- Price Range: $300,000–$500,000+
- Cost per sq ft: $400–$550/sq ft
- Timeline: 6–10 months
- Within or attached to existing home — basement suites, additions, above-garage
- Governed by SMC 23.44.025

### Garage Conversion ADU
- URL: https://www.seattleadubuilders.com/services/garage-conversion
- Price Range: $200,000–$325,000+
- Cost per sq ft: $400–$500/sq ft
- Timeline: 4–8 months
- Convert existing garage into permitted dwelling unit

### Basement ADU Conversion
- URL: https://www.seattleadubuilders.com/services/basement-adu
- Price Range: $225,000–$400,000
- Cost per sq ft: $400–$500/sq ft
- Timeline: 4–8 months

### ADU Permitting Services
- URL: https://www.seattleadubuilders.com/services/adu-permitting
- Price: Free when we build your ADU
- Timeline: 6–14 weeks (Seattle DCI: 6–10 wks, King County DPER: 8–14 wks)

## Regulations & Laws
- ADU Laws Hub: https://www.seattleadubuilders.com/adu-laws
- Washington HB 1337: https://www.seattleadubuilders.com/adu-laws/washington-hb-1337
- Seattle City Code (SMC 23.44.041/23.44.025): https://www.seattleadubuilders.com/adu-laws/seattle-city
- King County Code (KCC Title 21A): https://www.seattleadubuilders.com/adu-laws/king-county
- Seattle vs King County Comparison: https://www.seattleadubuilders.com/adu-laws/seattle-vs-king-county
- Shoreline Management Act: https://www.seattleadubuilders.com/adu-laws/shoreline-management-act
- Owner Occupancy: https://www.seattleadubuilders.com/adu-laws/owner-occupancy
- Two ADUs Per Lot: https://www.seattleadubuilders.com/adu-laws/two-adus-per-lot
- Short-Term Rentals: https://www.seattleadubuilders.com/adu-laws/short-term-rentals

## Permitting Guides
- Permitting Hub: https://www.seattleadubuilders.com/permitting
- Seattle Permits (DCI): https://www.seattleadubuilders.com/permitting/seattle
- King County Permits (DPER): https://www.seattleadubuilders.com/permitting/king-county
- Permit Timeline: https://www.seattleadubuilders.com/permitting/timeline
- Permit Costs: https://www.seattleadubuilders.com/permitting/costs

## ADU Guides
- ADU Guide Hub: https://www.seattleadubuilders.com/adu-guide
- Seattle Guide: https://www.seattleadubuilders.com/adu-guide/seattle
- King County Guide: https://www.seattleadubuilders.com/adu-guide/king-county

## Neighborhoods (Seattle)
- Neighborhoods Hub: https://www.seattleadubuilders.com/neighborhoods
- Ballard: https://www.seattleadubuilders.com/neighborhoods/ballard
- Capitol Hill: https://www.seattleadubuilders.com/neighborhoods/capitol-hill
- Columbia City: https://www.seattleadubuilders.com/neighborhoods/columbia-city
- Beacon Hill: https://www.seattleadubuilders.com/neighborhoods/beacon-hill
- West Seattle: https://www.seattleadubuilders.com/neighborhoods/west-seattle
- Fremont: https://www.seattleadubuilders.com/neighborhoods/fremont
- Ravenna: https://www.seattleadubuilders.com/neighborhoods/ravenna
- Queen Anne: https://www.seattleadubuilders.com/neighborhoods/queen-anne
- Magnolia: https://www.seattleadubuilders.com/neighborhoods/magnolia
- Madrona: https://www.seattleadubuilders.com/neighborhoods/madrona
- Northgate: https://www.seattleadubuilders.com/neighborhoods/northgate
- Maple Leaf: https://www.seattleadubuilders.com/neighborhoods/maple-leaf
- Greenwood: https://www.seattleadubuilders.com/neighborhoods/greenwood
- Rainier Valley: https://www.seattleadubuilders.com/neighborhoods/rainier-valley
- Mount Baker: https://www.seattleadubuilders.com/neighborhoods/mount-baker

## Key Cost Data
- DADU (detached) in Seattle: $450,000–$800,000+
- Attached ADU: $300,000–$500,000+
- Garage Conversion: $200,000–$325,000+
- Basement ADU: $225,000–$400,000
- Permit fees (Seattle): $8,000–$20,000
- Total pre-construction soft costs: $20,000–$50,000
- Typical ADU rent in Seattle: $2,000–$3,500/month

## Educational Resources
- ADU Costs in King County: https://www.seattleadubuilders.com/adu-costs-king-county
- ADU Design: https://www.seattleadubuilders.com/adu-design
- Sustainable ADU Construction: https://www.seattleadubuilders.com/sustainable-adu-construction
- Prefab vs Site-Built ADUs: https://www.seattleadubuilders.com/prefab-vs-site-built-adu
- ADU Financing Options: https://www.seattleadubuilders.com/adu-financing
- ADU Rental Income in Seattle: https://www.seattleadubuilders.com/adu-rental-income-seattle
- Can I Build an ADU?: https://www.seattleadubuilders.com/can-i-build-an-adu
- ADU Parking Requirements: https://www.seattleadubuilders.com/adu-parking-requirements
- ADU for Aging Parents: https://www.seattleadubuilders.com/adu-for-aging-parents
- ADU Construction Timeline: https://www.seattleadubuilders.com/adu-construction-timeline
- ADU vs Tiny Home: https://www.seattleadubuilders.com/adu-vs-tiny-home
- Backyard Cottage Guide: https://www.seattleadubuilders.com/backyard-cottage-seattle
- DADU vs ADU Explained: https://www.seattleadubuilders.com/dadu-vs-adu
- ADU Property Tax in Washington: https://www.seattleadubuilders.com/adu-property-tax-washington
- Mother-in-Law Suite: https://www.seattleadubuilders.com/mother-in-law-suite
- ADU Floor Plans: https://www.seattleadubuilders.com/adu-floor-plans
- ADU Insurance Guide: https://www.seattleadubuilders.com/adu-insurance-guide
- Is an ADU Worth It?: https://www.seattleadubuilders.com/is-an-adu-worth-it
- ADU vs Home Addition: https://www.seattleadubuilders.com/adu-vs-home-addition
- Two ADUs Strategy: https://www.seattleadubuilders.com/two-adus-strategy
- Best Time to Build an ADU: https://www.seattleadubuilders.com/best-time-to-build-adu
- How to Hire an ADU Contractor: https://www.seattleadubuilders.com/how-to-hire-adu-contractor
- ADU Design Mistakes: https://www.seattleadubuilders.com/adu-design-mistakes
- ADU Cost Per Square Foot: https://www.seattleadubuilders.com/adu-cost-per-square-foot
- Washington ADU Laws 2026: https://www.seattleadubuilders.com/washington-adu-laws-2026
- ADU Septic Requirements: https://www.seattleadubuilders.com/adu-septic-requirements
- ADU Electrical Requirements: https://www.seattleadubuilders.com/adu-electrical-requirements
- ADU Rental Agreement Guide: https://www.seattleadubuilders.com/adu-rental-agreement
- ADU Zoning in Seattle: https://www.seattleadubuilders.com/adu-zoning-seattle
- FAQ: https://www.seattleadubuilders.com/faq
- ADU vs Guest House: https://www.seattleadubuilders.com/adu-vs-guest-house
  Key differences between a permitted ADU and a guest house, including legal status, utility requirements, and rental potential in Seattle.
- ADU vs Shed Conversion: https://www.seattleadubuilders.com/adu-vs-shed-conversion
  Can you convert a shed into an ADU? Permit requirements, code compliance, and when a shed conversion makes sense vs building new.
- ADU as Home Office: https://www.seattleadubuilders.com/adu-home-office
  Using an ADU as a dedicated home office or studio space in Seattle — zoning, design tips, and tax implications for remote workers.
- ADU Impact on Home Value: https://www.seattleadubuilders.com/adu-home-value
  How building an ADU affects your property value in Seattle and King County, with local appraisal data and ROI analysis.
- ADU Size Guide: https://www.seattleadubuilders.com/adu-size-guide
  How to choose the right ADU size — studio, one-bedroom, or two-bedroom — based on your lot, budget, and intended use.
- ADU Kitchen & Bathroom Design: https://www.seattleadubuilders.com/adu-kitchen-bathroom-design
  Design strategies for compact ADU kitchens and bathrooms that maximize functionality in small square footage.
- House Hacking with an ADU: https://www.seattleadubuilders.com/house-hacking-adu
  How Seattle homeowners use ADU rental income to offset mortgages and build wealth through house hacking strategies.
- Multigenerational Living in Seattle: https://www.seattleadubuilders.com/multigenerational-living-seattle
  ADUs as a solution for multigenerational families in Seattle — keeping aging parents close while maintaining independence.
- Seattle Housing Crisis & ADUs: https://www.seattleadubuilders.com/seattle-housing-crisis-adu
  How Seattle's housing shortage is being addressed through ADU construction and HB 1337.
- ADU Building Checklist: https://www.seattleadubuilders.com/adu-building-checklist
  Complete step-by-step checklist for building an ADU in Seattle — from pre-planning and design through permitting, construction, and move-in.
- Why Build an ADU?: https://www.seattleadubuilders.com/why-build-an-adu
  The top reasons Seattle homeowners are building ADUs — rental income, family housing, property value, and more.
- ADU Plumbing Requirements: https://www.seattleadubuilders.com/adu-plumbing-requirements
  Plumbing requirements for ADUs in King County — sewer vs septic, water connections, and code compliance.
- ADU HVAC & Heating: https://www.seattleadubuilders.com/adu-hvac-heating-cooling
  Heating and cooling options for ADUs in the Pacific Northwest — heat pumps, mini-splits, and energy efficiency.
- ADU Accessibility & ADA: https://www.seattleadubuilders.com/adu-accessibility-ada
  Designing accessible ADUs for aging in place — zero-step entry, wider doorways, and ADA-compliant features.
- ADU Maintenance Guide: https://www.seattleadubuilders.com/adu-maintenance-guide
  Annual maintenance checklist for ADU owners — HVAC, plumbing, exterior, and tenant-readiness tasks.
- Selling a Home with an ADU: https://www.seattleadubuilders.com/selling-home-with-adu
  How an ADU affects your home sale — appraisal impact, buyer appeal, and marketing strategies for ADU properties.

## Core Pages
- Home: https://www.seattleadubuilders.com
- All Services: https://www.seattleadubuilders.com/services
- Process: https://www.seattleadubuilders.com/process
- Pricing: https://www.seattleadubuilders.com/pricing
- About: https://www.seattleadubuilders.com/about
- Contact: https://www.seattleadubuilders.com/contact
- Portfolio: https://www.seattleadubuilders.com/portfolio
- Resources: https://www.seattleadubuilders.com/resources
- Free Feasibility Study: https://www.seattleadubuilders.com/feasibility

## Contact
- Website: https://www.seattleadubuilders.com
- Contact form: https://www.seattleadubuilders.com/contact
- Service area: Seattle and King County, Washington