Arlington ADU Cost: What You'll Actually Pay — and Why the Range Is So Wide

ADU costs in Arlington typically range from $120,000 to $450,000+ depending on type and scope. Basement ADU conversions generally range from $120,000–$200,000. Attached additions range from $180,000–$320,000. Detached backyard cottages range from $220,000–$450,000+. Use our Pricing Guide for current ranges.

The five primary cost drivers are: (1) ADU type (detached costs more than interior conversion), (2) size and finish level, (3) existing utility infrastructure (adding new service connections adds cost), (4) site conditions (slope, soil, access), and (5) permit and design fees.

Common unexpected costs include utility connection upgrades, soil remediation, structural reinforcement for interior conversions, and permit revision cycles. Berriz Design Build conducts a thorough site evaluation before providing estimates to identify these factors upfront.

Yes. A well-designed ADU in Arlington typically adds $150,000–$300,000 to property value depending on type and quality. Rental income potential also contributes to the investment case. Berriz Design Build designs ADUs with both livability and resale value in mind.

Yes. Common financing options include home equity loans, HELOCs, cash-out refinancing, and construction loans. Some lenders offer ADU-specific financing products. Berriz Design Build can connect you with lenders experienced in Northern Virginia ADU financing.

The most accurate estimate requires a site visit and zoning analysis. Berriz Design Build conducts initial consultations to evaluate your lot, existing infrastructure, and goals before providing a detailed estimate. Use our Pricing Guide for current ranges, then connect with us for a property-specific assessment.