Garage, Basement and Detached ADU Construction Services in Portland, Oregon
With over 17 years of construction experience in the Portland metro area, we help clients turn underused space—like garages, basements, and backyards—into fully livable dwellings that add long-term value.
What is an ADU?
An Accessory Dwelling Unit—commonly known as a granny flat, in-law unit, or secondary suite—is a smaller, self-contained residential structure built on the same lot as a primary residence. ADUs can be attached to the main home (like a basement or converted garage) or detached (like a backyard cottage). These units typically include a sleeping area, bathroom, kitchen, and private entrance, making them ideal for independent living.
Why Build an ADU in Portland?
Portland has become one of the most ADU-friendly cities in the country, with streamlined permitting processes and incentives to encourage their construction. Whether you’re interested in housing family or earning rental income, an ADU offers major benefits:
- Rental Income: Many Portland homeowners build ADUs as long-term rentals or short-term Airbnb properties to generate passive income.
- Multi-Generational Living: ADUs provide privacy for extended family while keeping everyone close.
- Increased Property Value: A well-designed ADU can significantly boost your home’s resale value.
- Sustainable Living: Smaller living spaces are more energy-efficient and align with Portland’s eco-conscious values.
Types of ADUs We Build
At Boss PDX, we offer full-service garage conversions and new construction options for every type of ADU, including:
- Detached ADUs (DADUs): Backyard cottages built from the ground up, ideal for rentals or guest houses.
- Attached ADUs: Additions that share one wall with the main home but include a separate entrance.
- Garage Conversions: Transform your existing garage into a fully livable dwelling complete with plumbing, HVAC, and kitchen amenities.
- Basement ADUs: Convert your unused basement into an income-producing rental or family suite.
Portland ADU Zoning & Permit Guidelines
Thanks to progressive housing policies, Portland has made it easier than ever to build ADUs. Here are some basics of local regulations:
- One ADU is allowed per residential lot (in some cases, two are allowed—one attached and one detached).
- There is no minimum lot size to build an ADU in Portland.
- ADUs must meet basic size requirements (typically max 800–1,200 sq. ft. depending on the type).
- Short-term rentals require a permit from the city of Portland.
Boss PDX manages the entire permitting process for you, ensuring that your project moves smoothly from design to final inspection.
Our ADU Design & Build Process
As a design-build general contractor, we streamline the entire experience. Here’s what it looks like when you partner with Boss PDX to create your Portland ADU:
- Initial Consultation: We visit your property to understand your goals, budget, and timeline.
- Custom Design: Our design team creates a personalized layout based on your vision and Portland code requirements.
- Permitting: We submit all necessary plans and applications to the city on your behalf.
- Construction: Our licensed crew builds your ADU with high-quality materials and energy-efficient solutions.
- Final Walkthrough: We handle inspections and ensure your new ADU is move-in ready.
How Much Does an ADU Cost in Portland?
The cost of building an ADU in Portland varies based on size, complexity, and whether you’re converting existing space or starting from scratch. On average, you can expect:
- Garage ADU Conversion: $80,000 – $150,000+
- Detached ADU (new construction): $150,000 – $300,000+
- Basement ADU: $90,000 – $180,000+
Boss PDX provides detailed estimates and transparent pricing to keep you informed every step of the way. We also offer financing options for qualified homeowners.
Energy Efficiency & Sustainable Building
As a Portland-based contractor, we understand the importance of green building. Our ADUs are built with energy-efficient windows, insulation, and heating systems that reduce utility costs and support environmental sustainability. Ask us about integrating solar panels, rainwater harvesting, and eco-friendly materials into your ADU project.
