Go Far®ADU & DADU builder · Renton
ADU & DADU builder for Renton.
Renton has done more than almost any city in King County to make ADUs easy: a Permit-Ready ADU program with pre-approved, pre-engineered cottage plans and expedited review, and a code updated in 2025 to meet Washington’s two-unit ADU law. Go Far Construction builds permitted, finished ADUs across Renton — permit-ready models and fully custom — ground-up backyard cottages, basement apartments, garage conversions, and attached units, from a family-owned, licensed Washington general contractor.
Washington’s ADU law — HB 1337 — sets the statewide floor of two accessory units per lot, and Renton updated its code in 2025 to meet it, so most residential lots can carry two accessory units. What fits on your parcel still comes down to zoning, lot coverage, and setbacks, which we confirm with the City of Renton before design begins. Our ADU vs. DADU guide walks through which route fits which lot.
Renton’s standout is the Permit-Ready ADU program: a set of pre-approved, pre-engineered detached cottage plans from roughly 415 to 1,000 square feet, free to use, with an expedited path through review. Starting from a permit-ready model trades some customization for real savings in design fees and approval time — and we build both ways, adapting a city base plan to your lot or designing a custom cottage from scratch when the site or the brief calls for it.
On budget: basement ADU conversions and garage conversions in this market generally land between $100,000 and $250,000 depending on the starting condition of the space, while a new-build detached cottage typically runs $250,000 to $450,000 including site work, utilities, and soft costs — permit-ready plans trim the soft-cost side. The full math lives in our ADU cost guide and DADU cost guide, and the rental side pencils well in Renton, where Boeing, the Landing, and some of the last attainable neighborhoods in King County keep small rentals in steady demand; ADU financing options covers how owners fund the build.
We build every route to a second unit: basement conversions, garage conversions, attached mother-in-law suites, and ground-up DADUs on the larger lots of the Highlands, Benson Hill, and Kennydale. Permits run through the City of Renton; we prepare the application, carry fees in an itemized written price, and meet every inspector on site, as on all our Renton projects.
What we build in Renton
Renton ADU questions
How much does it cost to build an ADU in Renton?
Basement ADU conversions and garage conversions generally land in the $100,000–$250,000 range depending on the starting condition of the space. A new-build detached ADU (backyard cottage) typically runs $250,000–$450,000 including construction, site work, utility connections, and soft costs — starting from one of Renton’s permit-ready plans trims the design and approval side of that. Every project gets an itemized written estimate before design is finalized.
What is Renton’s Permit-Ready ADU program?
The city offers a set of pre-approved, pre-engineered detached ADU base plans — roughly 415 to 1,000 square feet in a range of styles — that are free to use and move through an expedited review. You still need a site-specific application showing where the cottage sits on your lot. We handle that application and build either a permit-ready model or a fully custom design.
How many ADUs does Renton allow on a lot?
Renton updated its ADU code in 2025 to align with Washington’s statewide ADU law, HB 1337, which sets a floor of two accessory units on most residential lots. Exactly what fits on your parcel depends on zoning, lot coverage, and setbacks, so we confirm the numbers with the City of Renton before design begins.
Do you handle the Renton permits and inspections?
Yes — whether it’s a permit-ready model or a custom cottage, we prepare the City of Renton application, include permit fees in your itemized written estimate, and meet every inspector on site from foundation to final.
Plan your project
Costs, rules, and timelines for Renton ADU projects: ADU costs · DADU costs · Washington’s ADU law · ADU timelines · ADU financing · Seattle ADUs · Bellevue ADUs · our Renton page