ADU Design and Build Services by Neil Kelly Washington
Neil Kelly Washington offers accessory dwelling unit (ADU) design and build services for homeowners across the Northwest. Adding an ADU to a property is a practical way to increase both its value and functionality. These separate residential living spaces — sometimes called backyard cottages, in-law suites, or granny flats — are built on the same lot as a single-family home and can serve a range of purposes, from housing family members to generating rental income.
Neil Kelly Washington works with clients on several types of accessory dwelling units, depending on the existing property layout and the homeowner's goals:
- New construction of a detached ADU or freestanding backyard cottage
- Garage conversion or expansion of an existing secondary structure into a living space
- Conversion of interior spaces such as a basement or attic within the main home
- Addition of an attached ADU to the primary residence
While building a compact living space might seem straightforward, local regulations can be complex. Careful planning and efficient design are important factors in ensuring that a small space remains comfortable and livable. Neil Kelly Washington's design/build team has experience navigating local requirements and helping clients find solutions that fit their property, budget, and intended use.
Custom ADU Design and Construction
For homeowners interested in a custom approach — whether that means an attached ADU, a garage conversion contractor project, or a one-of-a-kind freestanding casita — Neil Kelly Washington brings design expertise and construction craftsmanship to the process. Their team works to balance design preferences with practical functionality, budget considerations, and energy efficiency goals.
As an example of their work, a Southeast Portland ADU project combined contemporary Northwest design with industrial elements. The unit was intended for the short-term rental market, so the team prioritized durable, easy-to-clean materials and finishes. The build was also designed to be energy efficient and solar powered.
Common questions homeowners have when considering an ADU include what the unit must contain. Depending on local regulations, an ADU typically needs to include:
- Sleeping, kitchen, and bathroom facilities
- At least one operable window or exterior door for emergency egress
- Heating controls separate from the primary dwelling
- Connection to water and sewer services
What to Know Before Building an ADU
The cost of building an ADU varies depending on the type of unit, the property, local building regulations, and other factors. A detached ADU builder project will generally differ in cost from a basement conversion or JADU contractor engagement. Speaking with a design consultant is the most reliable way to get accurate cost estimates for a specific project.
Regarding design plans, ADUs that are tailored to an existing property tend to offer better functionality and resale value than off-the-shelf plans. That said, some municipalities in Oregon do offer pre-approved plan sets to help streamline the permitting process. Neil Kelly Washington's consultants can help homeowners identify the right starting point based on their goals.
From a legal standpoint, most ADU projects — whether new construction or a garage conversion — require a building permit. Depending on the scope of work, electrical, plumbing, or mechanical permits may also be necessary. Neil Kelly Washington's team can help clients understand what applies in their specific location and ensure the project meets all relevant requirements.
For homeowners in the Northwest considering adding an accessory dwelling unit, Neil Kelly Washington offers a design consultation as a starting point to explore options and possibilities.
