Vancouver & Portland ADU Builders
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Your Trusted ADU Builder Near You
An Accessory Dwelling Unit, or ADU, is a secondary housing unit located on the same lot as your primary residence. It is a fully self-contained additional living space with a kitchen, bathroom, sleeping area, and a separate entrance.
Across Portland, Oregon, and Vancouver, Washington, ADUs are becoming one of the most practical ways to add value to a single-family home. Known as granny flats, backyard cottages, in-law suites, or casitas, they all provide flexible, affordable, and functional living space.
At Amplified Renovations, we specialize in ADU design and construction. We bring your vision to life while guiding you through zoning, permitting, and construction. Our role is not just to build but to simplify, educate, and ensure your ADU project is delivered with craftsmanship, high-quality, and compliance.
ADU Design Features Homeowners Request Most
Northwest-Ready Exteriors: Fiber cement siding, cedar trim, metal or architectural-shingle roofs.
Sustainability: Mini-split heat pumps, tankless water heaters, ERV ventilation, and solar-ready roofs.
Light & Space Maximization: Large corner windows, daylight basements, clerestory windows, and open floor plans.
Smart Storage: Built-in cabinetry, under-stair storage, and multifunctional furniture.
Covered Outdoor Space: Small porches or patios that extend living space into the yard.
By combining thoughtful layouts with durable materials and energy-efficient systems, ADUs in Portland and Vancouver are designed to feel like true homes, not secondary afterthoughts.
Why Build an Accessory Dwelling Unit in Portland and Vancouver?
The Pacific Northwest has embraced ADU construction more than many other regions. Rising housing demand, shifting family needs, and the push for more sustainable living all make ADUs a smart investment.
Rental Income Potential
A well-designed one-bedroom ADU in Portland can rent for $1,500 to $2,500 per month, depending on neighborhood and finishes. That translates to more than $20,000 annually, enough to offset or cover a mortgage. For many homeowners, an ADU is both supplemental income and a long-term financial strategy.
Multigenerational Living Solutions
With rising home costs, many families are finding it more practical for parents, grandparents, adult children, or other family members to live on the same property while maintaining independence. Adding an ADU provides affordable housing with privacy and autonomy. Parents can age in place near their children, young adults can save on housing, and families can reduce childcare costs by staying close.
Long-Term Property Value Growth
A 2020 Freddie Mac study found that homes with legal ADUs sell for a premium, often increasing property values by 20% to 30%. In Portland and Vancouver, where demand is high, buyers see a move-in-ready ADU as a versatile asset, whether for rental, guest use, or family housing.
Sustainability and Flexibility
ADUs align with Portland and Vancouver’s commitment to sustainable growth. They allow more people to live in existing neighborhoods without expanding sprawl, and their smaller footprint makes them energy-efficient. Many are designed with modern HVAC systems, high insulation, and solar readiness. Over time, an ADU can shift from rental housing to family space, office, or caregiver suite, adapting to your life’s changes.
Popular ADU Types and How They Are Used
ADUs come in several forms, each with unique benefits depending on your property, budget, and goals. In the Portland–Vancouver region, five styles stand out.
Detached ADUs (Backyard Cottages)
Detached ADUs are standalone homes built in the backyard or on the side of a lot. They often resemble miniature houses or a guest house with pitched roofs, porches, and Northwest-friendly siding like fiber cement with cedar trim. In Portland, they are limited to 800 square feet or 75% of the main home’s living area; in Vancouver, they can be up to 1,000 square feet. Detached ADUs are popular for rentals, multigenerational housing, or guest use thanks to their privacy.
Attached Accessory Dwelling Units (ADUs)
Attached ADUs share a wall with the primary dwelling but function independently, often with private entrances, kitchens, and bathrooms. They are cost-effective because they tie into existing utilities and structures. Many families use attached ADUs to house aging parents or adult children affordably.
Garage Conversions
Garage conversions are a cost-effective way to add an ADU since they use an existing footprint. Detached garages in Portland’s older neighborhoods are often converted into studios or one-bedroom units. While not as customizable as new builds, garage ADUs are budget-friendly and can be completed faster than standalone construction.
Basement ADUs
Basement ADUs convert existing lower levels into separate apartments. They require attention to natural light, soundproofing, and egress windows for safety. They’re ideal for creating income-generating rentals or private living spaces without changing the property’s exterior.
Prefabricated or Modular ADUs
Prefabricated ADUs are factory-built and delivered for installation on site. They provide predictable costs and faster timelines while still being subject to zoning and setback rules. Many modular units feature sleek modern designs and eco-friendly construction.
Our Proven ADU Building Process
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We start with a free evaluation to review zoning, setbacks, and lot coverage. In both Portland and Vancouver, up to two ADUs are permitted per lot. During this step, we assess utilities, slopes, and overlays like floodplains or historic districts that could affect design.
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Once eligibility is confirmed, we create designs tailored to your property. You’ll decide whether a studio, one-bedroom, or two-bedroom layout fits best. In Portland, we can also use pre-approved ADU plan sets, which can reduce fees and speed up approval.
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Permitting is often the most complex step. Portland’s Bureau of Development Services requires a building permit plus trade permits for plumbing, electrical, and mechanical systems. Vancouver uses its own ADU checklist and review process. We handle drawings, submittals, and communication with reviewers to keep your project moving.
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With permits approved, we manage construction from foundation and framing to finishes. Every ADU we build follows the Oregon Residential Specialty Code, with inspections scheduled at key milestones. Our focus is durability, compliance, and long-term performance.
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The final step is closing permits and handing over your completed unit. We provide warranties, manuals, and explain rental-related rules, including Portland’s SDC Waiver Program. You leave with a finished ADU that’s ready for use.
Building an ADU requires navigating regulations, coordinating permits, and making design decisions. Our process ensures nothing is overlooked.
Common Portland ADU Layouts & Floor Plans
Every Portland ADU is unique, but certain layouts have proven especially popular in the Pacific Northwest. These layouts maximize functionality and comfort while adhering to zoning requirements.
Studio ADUs (320–450 sq ft)
Open-concept living area with compact kitchen.
Often features a sleeping loft or Murphy bed for flexibility.
Vaulted ceilings and skylights help small spaces feel expansive.
One-Bedroom ADUs (400–650 sq ft)
Separate bedroom for privacy.
Popular with long-term renters.
Fits nicely on smaller urban lots without overwhelming the yard.
Two-Bedroom ADUs (700–1,000 sq ft)
Full living space suitable for families or multigenerational living.
The most common choice for homeowners building ADUs is as permanent family residences.
In Portland, the space must remain under 800 sq ft (or 75% of the main dwelling size).
ADU Building Costs | Portland & Vancouver
| ADU Type | Average Cost Range | Notes |
|---|---|---|
| Detached ADU (new build) | $200,000 – $350,000+ | Most flexible, highest privacy, typically larger |
| Garage Conversion | $150,000 – $220,000 | Utilizes existing footprint, more cost-effective |
| Basement Conversion | $150,000 – $220,000 | Requires light/egress solutions and soundproofing |
| Prefabricated/Modular ADU | $180,000 – $250,000+ | Faster build, but site prep/utilities still required |
ADU Builidng Timeslines To Expect
| Phase | Estimated Duration | Notes |
|---|---|---|
| Feasibility & Design | ~1 month | Includes zoning review and layout planning; can be shorter if homeowner has worked ahead. |
| Permitting | 2–6 months | Duration varies depending on jurisdiction. |
| Construction | 2–4 months | Affected by weather, site conditions, and inspection schedules. |
| Total Project Duration | ~4–10 months | From first consultation to move-in. |
We provide a detailed line-item estimate and personalized timeline after your site evaluation so you understand exactly what drives both cost and schedule.
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In Portland, detached ADUs are limited to the lesser of 800 square feet or 75% of the primary dwelling’s living area. In Vancouver, detached ADUs can be up to 1,000 square feet. Attached, basement, and garage conversions follow similar rules but may vary based on lot coverage and setbacks.
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Both Portland and Vancouver allow up to two ADUs on a single lot under current regulations.
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Neither Portland nor Vancouver requires additional parking for ADUs, though you must maintain any required spaces for the primary home.
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In Portland, short-term rentals are prohibited for ten years if you use the SDC Waiver Program, which exempts ADUs from system development charges. Without the waiver, ADUs can be used as Type A or Type B short-term rentals with proper permits. Vancouver permits short-term rentals under its own licensing rules.
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Both Portland and Vancouver allow retroactive permitting. Inspectors may require limited demolition to check hidden work. We can help legalize unpermitted ADUs by bringing them up to code.
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From start to finish, most ADU projects take four to ten months. This includes feasibility, design, permitting, construction, and final inspections.
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The most affordable way to build an ADU in Portland is usually to convert existing space rather than starting from scratch. Garage conversions and basement ADUs are generally the least expensive options because the structure already exists, you don’t have to pour a new foundation, frame exterior walls, or build a separate roof. Instead, costs go toward insulation, plumbing, electrical upgrades, egress windows, and interior finishes.
Detached ADUs, while popular for privacy and rental potential, tend to be more expensive since they require full site prep, utilities, and new construction. Prefabricated or modular ADUs can sometimes reduce costs and speed up build time, but site preparation, foundation work, and utility hookups are still required.
If budget is the top priority, the “cheapest” path is usually:
Garage Conversion
Basement Conversion
Small, simple detached ADU using a pre-approved city plan
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The cost to build an ADU in Portland varies depending on type, size, and complexity, but most projects fall in the $250 to $400 per square foot range.
Key factors that drive cost include:
Size & Layout: Larger ADUs cost more, but kitchens and bathrooms are the most expensive spaces per square foot.
Site Conditions: Sloped lots, tree removal, or long utility runs add cost.
Utility Upgrades: Many projects require trenching, sewer/water line upgrades, or electrical panel replacements.
Finishes & Materials: Basic finishes lower costs, while high-end cabinetry, tile, or appliances push numbers higher.
Permitting & Fees: Portland offers an SDC Waiver Program that can save tens of thousands if you agree not to use the ADU as a short-term rental for 10 years.
For a typical 600–800 sq ft detached ADU, homeowners can expect to spend $200K–$300K on average.
FAQs
Building an ADU in Portland or Vancouver can feel overwhelming. Our team of professional builders is here to answer any questions you may have about adding an ADU to your home.
Are you unsure if you’re allowed to build an ADU on your lot? Let our team conduct a feasibility check for an ADU building on your property, so you can determine with certainty whether constructing an ADU is possible.
Request a no-obligation ADU Feasibility Check Today.
Why Choose Amplified Renovations
Choosing the right ADU builder near you is as important as the project itself. At Amplified Renovations, we bring unmatched knowledge of Portland and Vancouver codes, permitting processes, and construction standards.
Our transparent design-build estimates give you clear expectations from the start. Our designs balance functionality, style, and long-term durability. Most importantly, we manage the ADU requirements complexity and local zoning so you can focus on the end result: a beautiful, code-compliant ADU that adds lasting value to your property.