What Is an ADU and Why Build One in Lake Oswego?

An accessory dwelling unit (ADU) is a secondary residential structure located on the same property as your primary home. In Lake Oswego, ADUs are a powerful way to increase property value, generate rental income, or create flexible living space for family members.

Common Reasons Lake Oswego Homeowners Build ADUs:

  • Long-term rental income or short-term rental potential
  • Multigenerational living (aging parents, adult children)
  • Guest accommodations with privacy
  • Home office or studio space
  • Increased property value and resale appeal

Lake Oswego’s strong housing demand and high property values make ADUs an especially strategic investment.

Why Choose Lamont Bros. For My Lake Oswego ADU Builder?

Lamont Bros. Design & Construction is a trusted Lake Oswego ADU builder offering full-service design and construction for detached, attached, and conversion ADUs.

Our design-build process simplifies planning, permitting, and construction, helping homeowners create high-quality accessory dwelling units that add value, flexibility, and long-term usability. 

Here's why Lake Oswego homeowners choose Lamont Bros. as their ADU Builder: 

  • Integrated Design-Build Team – One team from concept through construction
  • Local Expertise – Deep experience with Lake Oswego zoning and permitting
  • Transparent Process – Clear timelines, budgets, and communication
  • High-End Craftsmanship – Built for durability, functionality, and long-term value
  • Client-Centered Approach – Your goals guide every decision

Types of ADUs We Build

Lamont Bros. Design & Construction builds a variety of ADUs in Lake Oswego including kit-built, custom-designed, stand-alone, or attached, including garage or basement conversions. 

Detached ADUs

Standalone backyard homes offering maximum privacy and flexibility. Ideal for rentals or guest houses.

Attached ADUs

Additions connected to your main home, often sharing one wall. A great option for seamless integration into your home's design and aesthetics.

Garage Conversion ADUs

Transform an existing garage into a fully livable space while maximizing your current footprint.

Basement or Interior ADUs

Convert unused interior space into a functional, code-compliant dwelling unit.

Lamont Bros. Design & Construction

Lake Oswego | ADU Builder Portfolio

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Clackamas Crawlspace Conversion
Basement Family Room
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Start Planning Your Lake Oswego ADU

Our design-build team helps Lake Oswego homeowners plan accessory dwelling units (ADUs) that add flexibility, long-term value, and functional living space to their properties, from early feasibility questions through completed construction.

When you schedule a consultation with Lamont Bros. Design & Construction, you’re not committing to building an ADU. You’re simply starting a conversation about what’s possible on your Lake Oswego property.

Your consultation is designed to help you:

  • Clarify your goals for building an ADU, whether for multigenerational living, rental income, guest accommodations, or aging in place
  • Explore the best ADU type for your property, including detached backyard ADUs, garage conversions, or attached units
  • Understand Lake Oswego zoning requirements, permitting considerations, and what your specific lot can accommodate
  • Discuss realistic investment ranges for ADU projects in Lake Oswego and the surrounding Portland metro area
  • Determine whether a design-build approach is the right fit for planning and building your ADU

Since 2008, Lamont Bros. Design & Construction has helped hundreds of homeowners throughout the Portland area, including Lake Oswego, thoughtfully expand their homes through well-planned remodeling and construction projects. Our team focuses on providing clear, expert guidance early in the process so you can make confident decisions about your home, your property, and your investment.

Request a Consultation

Lake Oswego | ADU Builders

Frequently Asked Questions

How do I get started on an ADU project in Lake Oswego?

Start by scheduling a consultation with Lamont Bros. Design & Construction. Our team evaluates your property, zoning, and goals, then guides you through feasibility, design, and budgeting so you can move forward with clarity.

What are the zoning requirements for ADUs in Lake Oswego?

Lake Oswego has specific regulations related to size, setbacks, height, and occupancy. Lamont Bros. Design & Construction manages zoning analysis and ensures your ADU design complies with all local requirements.

How long does it take to build an ADU in Lake Oswego?

Most ADU projects take several months from design through construction. With Lamont Bros. Design & Construction’s design-build process, timelines are streamlined because design, permitting, and construction are coordinated under one team.

Can I convert my garage to an ADU in Lake Oswego?

Yes, garage conversions are a popular ADU option in Lake Oswego. Lamont Bros. Design & Construction evaluates your existing structure and transforms it into a fully functional, code-compliant living space.

Is building and ADU a good investment in Lake Oswego?

In many cases, yes. ADUs can increase property value and provide rental income. Lamont Bros. Design & Construction helps homeowners design ADUs that align with both lifestyle goals and long-term financial returns.

Do I need a design-build firm for my ADU project?

Working with a design-build firm like Lamont Bros. Design & Construction simplifies the entire process by keeping design, budgeting, and construction aligned—reducing risk, delays, and miscommunication.

What utilities are required for an ADU?

ADUs require connections to water, sewer, and electrical systems. Lamont Bros. Design & Construction handles utility planning and coordination to ensure your ADU meets all infrastructure requirements.

How much does an ADU cost in Lake Oswego?

The cost of building an ADU in Lake Oswego varies based on size, type, site conditions, and design complexity. Most projects fall within a broad range depending on whether you are building new or converting existing space.

Key cost factors include:

  • Size and square footage
  • Site preparation and utilities
  • Structural complexity
  • Interior finishes and customization
  • Permitting and system development charges (SDCs)

Working with an experienced design-build firm like Lamont Bros. Design & Construction helps you establish a realistic budget early and avoid costly surprises.

Read more:

The Lamont Bros. Difference

Award Winning Craftsmanship

Lamont Bros. has earned recognition as a multi-award-winning Portland design-build firm, including the NARI Remodeler of the Year award and Houzz Best Service every year since 2016.

Client-Verified Excellence

Lamont Bros. maintains a 4.8-star average rating across Google, Houzz, and Yelp, reflecting consistent client satisfaction across hundreds of completed remodeling projects.

20 Years of Experience

Since 2008, Lamont Bros. has completed 850+ remodeling projects across the Portland metro area, including kitchens, bathrooms, additions, and ADUs in Portland, Beaverton, Lake Oswego, West Linn, and Oregon City.