Skip to main content Skip to content Detached and attached ADUs, garage conversions, and basement ADUs, permitted and built to match the main home. Woodland Construction Group builds accessory dwelling units across Lake Oswego, one accountable team from first sketch to final inspection.
Review the City of Lake Oswego ADU permitting requirements before you begin.Building an ADU in Lake Oswego, Oregon? An accessory dwelling unit is a second, independent home on your property: a detached unit in the backyard, an attached addition, a finished garage, or a basement conversion, each with its own kitchen and bath.
It is one of the highest-value ways to use a lot in a supply-constrained market, whether you are housing aging parents, an adult child, a long-term guest, or building rental income. Because an ADU spans structure, utilities, siting, and city approvals, the builder you choose controls the outcome.
Lake Oswego is its own jurisdiction with its own permitting path, so the right partner is one who knows that process and builds the unit to match your home rather than parking an add-on in the yard.
An ADU in Lake Oswego commonly runs $180,000 to $420,000+ in 2026, depending on detached versus attached, size, and site work. Detached units sit at the higher end because they need their own foundation, roof, and utility connections; attached, basement, and garage-conversion ADUs can land lower.
An ADU adds multigenerational space or rental income on land you already own in a high-value market with the top-ranked Lake Oswego School District, which is why many owners build rather than relocate.
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An ADU is one of the highest-value ways to use a Lake Oswego lot. It opens up aging-parent or adult-child housing, a guest house, a home office, or rental income, all on land you already own in a market with a detached-home median around $1.1M and a top-school district that keeps families in place.
Because Lake Oswego is supply-constrained, owners tend to remodel and add rather than relocate and lose their neighborhood and schools. An ADU lets you add a second household to the property without giving any of that up, and it keeps your options open as your family’s needs change over the years.
A detached unit built to match the main home protects the look of your property and the character of the neighborhood. See how an ADU fits a larger plan on our whole-home renovation page.
Woodland Construction Group – 18 Years Experience – Serving Lake Oswego, Oregon
Our team of licensed contractors designs and builds detached and attached ADUs, garage conversions, and basement units across Lake Oswego, managing City of Lake Oswego approvals, siting, and finishes under one accountable contract.
A detached ADU built to match the main home adds a second, independent household to your Lake Oswego property, multigenerational space or rental income, without giving up your lot, your neighborhood, or your schools.
Six ways we add an independent dwelling to a Lake Oswego property. Each is engineered for the way the space will actually be lived in, and built to match the main home, not just to pass inspection.
A standalone home in the backyard with its own foundation, roof, and entrance, designed and built to match the main house and protect the look of the lot.
An independent unit joined to the main home, sharing structure and utilities to keep the footprint efficient while keeping the living quarters fully separate.
Turning existing garage space into a finished, code-compliant dwelling with insulation, plumbing, and a full kitchen and bath, often the most economical path.
Carving an independent unit out of the lower level or interior of the home, with a separate entrance, egress, and the systems an independent dwelling needs.
Every unit gets its own kitchen and bathroom so it lives independently, whether it houses family or earns income as a long-term rental.
Coordinated siding, roofline, and trim, plus utility connections, grading, walkways, and landscaping that tie the unit into the property and the neighborhood.
How We Work
One team, one contract, from the first measurement to the final walkthrough, with no handoffs between designer, builder, and trades: design and 3D layouts, material selection, permitting and inspections, careful demolition, licensed construction, and a final walkthrough, all backed by our 1-year craftsmanship warranty.
See our full design-build processA look at the detached and finished accessory dwelling units we build for Lake Oswego and the surrounding metro.
Walk through every line that shapes the number, from unit type and size to foundation, utilities, and site work, with a calculator built on real Portland-area project data.
Engaging with Woodland for our home extension was a great decision. They were attentive to our vision, offered valuable insights, and completed the project on time. Their commitment to quality and craftsmanship is truly impressive.
A huge thank you to Woodland Construction Group for the beautiful job they did on our home extension. High-quality craftsmanship throughout.
Woodland Construction Group is an expert in their field. We are very satisfied with their work.
Timelines, cost, City of Lake Oswego permitting, and what to expect in 2026. If your question is not here, call us. We would rather answer it directly.
A detached ADU in Lake Oswego typically takes 7 to 11 months from design through final inspection, and an attached ADU or garage conversion often runs 5 to 8 months. Design and City of Lake Oswego plan review take a meaningful share of that timeline, and lots that trigger Sensitive Lands review or tree-removal permits add time. We build the schedule around the actual approval path for your lot, not a generic estimate.
In Lake Oswego, ADUs in 2026 commonly run about $180,000 to $420,000 or more. A detached ADU built to match the main home sits at the higher end because it needs its own foundation, roof, utilities, and site work. An attached ADU, basement ADU, or garage conversion can land lower because it shares structure and connections. Sloped or wooded lots and lake-adjacent sites add cost. You get an itemized estimate during design.
Permits and plan review go through the City of Lake Oswego Planning and Building department, its own jurisdiction, not the City of Portland. We confirm zoning, setbacks, lot coverage, and utility connections before design is final. Lots near creeks, Tryon Creek, wetlands, or steep wooded slopes may need Sensitive Lands review before grading or demolition, and the city tree-protection ordinance requires a removal permit for any tree 6 inches or larger in diameter, with some removals requiring a replacement tree. Woodland Construction Group manages siting and approvals.
We build four types: detached ADUs as a standalone home in the backyard, attached ADUs joined to the main house, garage conversions that turn existing space into a finished unit, and basement or interior ADUs carved out of the lower level. Each gets full living quarters, a kitchen and a bath, so the unit lives independently.
Both. Many Lake Oswego homeowners build an ADU for aging parents or an adult child who wants their own space close to family, and others use it for rental income or a long-term guest house. Because the unit has its own kitchen and bath, it works as fully independent living. We will design it for the use you have in mind, and a layout that adapts if that use changes later.
Yes. A detached unit built to match the main home protects the look of the property and the neighborhood. We coordinate siding, roofline, windows, and trim with the existing house, then handle the site work that ties it all together: utility connections, grading, walkways, and landscaping. The goal is an ADU that reads as part of the home, not an add-on parked in the yard.
For many Lake Oswego owners, yes. You are adding multigenerational space or rental income on land you already own in a supply-constrained, high-value market with the top-ranked Lake Oswego School District. An ADU gives you flexibility, housing for family, a home office, or income, without giving up your lot, your neighborhood, or your schools. In a market with a detached-home median around $1.1M, that flexibility holds real value.
Family-owned and based in Northwest Portland, we design and build ADUs across Lake Oswego and the surrounding communities.
Keep Exploring
Book a free on-site consultation. We will assess the lot and the main home, talk through unit type, layout, and budget, and walk you through the City of Lake Oswego path, with no pressure and no handoffs.
