Collins ADU Builders – ADU Construction Services in Portland
Collins ADU Builders is a Portland-based ADU contractor offering a range of accessory dwelling unit construction and design services for residential and commercial properties. Their work covers everything from detached ADU builds and garage conversions to junior ADU conversions and home additions, serving clients throughout Portland and the surrounding communities.
The company is licensed and bonded, and their team brings hands-on experience across the full scope of ADU construction. They handle permitting, design coordination, and construction through to final inspection, aiming to deliver projects that meet local code requirements and client expectations.
ADU Services Offered by Collins ADU Builders
Collins ADU Builders provides a broad set of services for property owners looking to add or convert living space:
- Detached ADU construction – The team builds standalone accessory dwelling units separate from the main residence. These backyard cottage and granny flat builds are suited for rental income, guest quarters, multigenerational living, or home office use. The process includes initial consultation, permit acquisition, construction, and final walkthrough.
- Garage conversion contractor services – Collins ADU Builders converts existing garages into functional living spaces, offering a practical route to adding an ADU without new ground-up construction.
- Attached ADU / home addition – For homeowners who want to expand their existing structure, the team designs and builds attached ADUs that integrate with the main home while providing a separate living unit.
- Junior ADU (JADU) contractor services – Junior ADUs are created by converting interior spaces within the existing home, such as a bedroom or suite. These conversions typically involve lower costs, shorter build timelines, and a more straightforward permitting process compared to full ADU builds. Collins ADU Builders manages design, permits, construction, and inspection for JADU projects.
- ADU design services – The design team offers site evaluation, feasibility assessments, custom layout creation, 3D renderings, material and finish consultation, and full permit-ready construction documents. They also provide guidance on optimizing ADU layouts for specific uses such as rental income, elder care, or professional workspace.
- Room additions – Beyond ADU-specific work, Collins ADU Builders also handles general home addition projects for residential and commercial clients.
For detached ADU projects, the team coordinates every phase from design through to final delivery. Whether the goal is a compact open-concept unit or a larger family-sized space, they work to match the build to the client's site conditions and budget.
Junior ADU conversions are handled with attention to local zoning requirements. Collins ADU Builders manages the full permit process and ensures the finished unit meets municipal standards while making practical use of existing interior space.
What to Expect When Working with Collins ADU Builders
Collins ADU Builders offers free initial consultations and estimates. Their stated approach includes transparent pricing with no hidden fees, and they provide a client satisfaction guarantee. The team handles permit coordination and compliance as part of their standard process, which can reduce the administrative burden on property owners navigating ADU regulations in Portland.
Their services are available to both homeowners and businesses in Portland, OR. For those considering an accessory dwelling unit builder in the Portland area, Collins ADU Builders covers the main ADU types — detached, attached, garage conversion, and JADU — along with the design work needed to get a project from concept to completion.
