Go Far®ADU & DADU builder · Seattle
ADU & DADU builder for Seattle.
Seattle has some of the most ADU-friendly rules of any big city in the country — two units per lot, no owner-occupancy requirement, no added parking in most cases. Go Far Construction turns that opportunity into finished, permitted square footage: basement apartments, garage conversions, and new backyard cottages, built by a family-owned, licensed Washington general contractor.
A Seattle residential lot can now hold the main house plus two accessory dwelling units — one attached and one detached, or two attached. Units can reach 1,000 square feet (1,200 for three-bedroom-plus layouts), detached cottages can rise roughly 32 feet in most Neighborhood Residential zones, and under Washington’s HB 1337 an ADU can even be condominiumized and sold separately. That is why the backyard cottage has quietly become one of the strongest investments a Seattle homeowner can make on land they already own — our Seattle ADU & DADU rules guide covers the full picture.
We build every route to a second unit: basement ADU conversions that turn underused lower floors into rental income, garage conversions, attached ADU additions, and ground-up DADUs — custom-designed, or built from Seattle’s pre-approved DADU plan gallery when speed through permitting matters most. Permits run through the Seattle Department of Construction and Inspections (SDCI); we prepare the application, include fees in an itemized written price, and meet every inspector on site.
What we build in Seattle
Seattle ADU questions
How much does it cost to build a DADU in Seattle?
A new-build detached ADU (backyard cottage) in Seattle typically runs $250,000–$450,000 including construction, site work, utility connections, and soft costs. Attached options cost less: basement ADU conversions and garage conversions generally land in the $100,000–$250,000 range depending on the starting condition of the space.
What are Seattle’s ADU rules right now?
Seattle allows up to two accessory dwelling units per residential lot — for example a basement apartment plus a backyard cottage. There is no owner-occupancy requirement and no off-street parking requirement for ADUs. Units can reach 1,000 square feet (1,200 for three-bedroom-plus units), and DADUs in most Neighborhood Residential zones can reach roughly 32 feet in height. Rules are zone-specific, so we confirm your lot’s exact numbers as part of a free feasibility conversation.
How long does it take to build an ADU in Seattle?
Basement and garage conversions typically run 5–9 months door to door including design and permitting. A new-build DADU typically runs 10–15 months from first design meeting to keys. Seattle’s gallery of pre-approved DADU plans can shorten permit review substantially compared with a custom design.
Do you handle Seattle permits?
Yes. ADUs and DADUs go through a standard building permit with the Seattle Department of Construction and Inspections (SDCI). We prepare and track the application, include fees in your itemized written estimate, and meet every inspector on site.
Plan your project
Costs, rules, and timelines for Seattle ADU projects: Seattle ADU & DADU rules · ADU costs · DADU costs · ADU timelines · ADU vs. DADU · ADU financing · HB 1337 explained · Bellevue ADUs · Lynnwood ADUs · Kirkland ADUs · Everett ADUs · Shoreline ADUs · Our Seattle page