Can I build an ADU on my property in Lake Oswego?

In many cases, yes. ADU eligibility depends on zoning rules, lot size, setbacks, and site conditions. A feasibility review helps determine what your property can support before design begins.

How much does it cost to build an ADU in Lake Oswego?

ADU costs vary based on factors such as size, site conditions, utilities, and finish selections. Detached ADUs typically cost more than conversions because they require new foundations and structures.

Is a detached ADU better than converting a garage?

Detached ADUs offer more privacy and flexibility, while garage conversions can be more cost-efficient by using an existing structure. The best option depends on your property and project goals.

Can I rent out an ADU?

Many homeowners build ADUs specifically for long-term rental income. Local regulations can affect rental use, so it's important to review city requirements before building.

What size can an ADU be in Lake Oswego?

ADU size limits are determined by local zoning rules and building regulations. Many ADUs range between 400 and 900 square feet, though the exact maximum depends on your lot and the type of ADU being built.

How do I start building an ADU in Lake Oswego?

The first step to building an ADU in Lake Oswego is evaluating your property’s zoning allowances and site conditions. A design-build team like Lamont Bros. Design & Construction can help determine feasibility, estimate costs, and create a design that meets your goals.

Lake Oswego ADU Builders

Lamont Bros. Design & Construction specializes in designing and building high-quality accessory dwelling units (ADUs) tailored to your property, goals, and lifestyle.

Whether you’re planning a detached backyard cottage, garage conversion, or in-home ADU, our team provides a streamlined design-build process that takes your project from concept through construction with clarity and precision.

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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.

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.

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Over nearly 20 years we've completed 850+ remodeling projects in the Portland metro area.