One of the most common questions from Seattle homeowners considering an ADU is: how much rent will it generate, and when will I break even? Here are realistic numbers based on current Seattle rental market data.
ADU Rental Rates in Seattle and the Eastside (2026)
- Studio ADU (350-500 sq ft): $1,400 – $1,900/month
- 1-bedroom ADU (500-700 sq ft): $1,800 – $2,400/month
- 2-bedroom ADU (700-900 sq ft): $2,400 – $3,200/month
- Mercer Island / Medina premium: Add 25-40%
- Kirkland / Redmond: $1,900 – $2,800/month for 1BR
ADU Cost vs. Rental Income: Break-Even Analysis
Example: A detached 600 sq ft 1-bedroom backyard cottage in Seattle:
- Total project cost: $320,000 (construction + design + permits)
- Monthly rental income: $2,100
- Annual gross income: $25,200
- Annual net income (after 10% vacancy + maintenance): ~$21,000
- Gross yield: 7.9%
- Break-even: approximately 15 years
A garage conversion ADU has a faster break-even:
- Total project cost: $140,000
- Monthly rental income: $1,600
- Annual net income: ~$16,000
- Gross yield: 11.4%
- Break-even: approximately 9 years
Additional Financial Benefits
- Property value increase: ADUs typically add $200,000-$400,000 to Seattle home values
- Multi-generational use: avoiding senior care facility costs for aging parents
- House hacking: offset mortgage with rental income
Piper Cole Architects designs ADUs that maximize rental income through smart layouts and finishes. See our ADU design service or contact us for a free consultation. Call 425-753-6452.
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Piper Cole Architects offers a free initial consultation for all project types — residential, commercial, ADU, and renovation. No obligation. Based in Kirkland, WA. Serving the entire Seattle metro area since 2000.