ADUs & DADUs.
Flexible, well-built living space that adds real value.
Silverstone Building builds attached ADUs and detached DADUs across the Seattle area and King County, to full-home standard. Attached or basement ADUs generally run $100,000–$250,000; detached DADUs often start around $300,000.
What it covers.
Accessory dwelling units, attached (ADU) and detached (DADU), for rental income, multi-generational living, a home office, or a guest house. Small footprints, but full homes in every way that matters.
Our approach.
An ADU is a complete house compressed into a small space (its own kitchen, bath, systems, and finishes), which makes the planning and coordination punch well above its square footage. We treat them with the same rigor as a much larger project, because they demand it.
What to consider.
Zoning and permitting are the first hurdle. Rules on size, height, and placement vary; Seattle and surrounding jurisdictions each have their own: including pre-approved DADU programs worth knowing about. We'll help you navigate them.
Utilities and site access add scope. Connecting a detached unit to power, water, and sewer is often a bigger part of the budget than people expect.
Small doesn't mean simple. Every trade a full house needs still has to fit, and fit well.
Indicative cost.
Attached or basement ADUs generally run $100,000–$250,000; detached DADUs often start around $300,000. See the Cost Guide.
ADU & DADU FAQ.
Attached or basement ADUs generally run $100,000–$250,000; detached DADUs often start around $300,000.
An ADU is attached to or within the main home; a DADU is a separate standalone structure. Zoning treats them differently.
Yes. Rules on size, height, and placement vary by jurisdiction, including King County pre-approved DADU programs, and we help you navigate them.
