Core ADU: A Thoughtfully Designed Accessory Dwelling Unit
Core ADU is a purpose-built accessory dwelling unit builder concept rooted in three foundational design guidelines. These include the Better Living Design Institute's Age-Friendly ADU Design Criteria, the U.S. Department of Energy's Advanced Wall Framing Technical Fact Sheet, and the Mandatory Minimum Design Requirements of the Nebraska Department of Energy & Environment's Dollar and Energy Saving Loan Program. Notably, compliance with the NDEE standard also allows homeowners to qualify for the Dollar and Energy Saving Loan Program, which offers a very low interest rate mortgage.
As a detached ADU builder, Core ADU prioritizes accessibility, energy efficiency, low embodied carbon construction, and low maintenance. Affordability is achieved through extreme efficiency and smart construction practices rather than compromise on quality or livability.
The defining feature of the Core ADU is its central "core" — a module containing the most construction-intensive elements: the kitchen, bathroom, and laundry, along with storage components. This core can be built off-site as a complete module or prefabricated as flat-packed components, delivered and installed on-site. This approach significantly limits construction time and minimizes disruption to the surrounding neighborhood.
Smart Space Planning and Flexible Configurations
The standard Core ADU plan is a 750 gross square foot, one-bedroom dwelling with an optional partition to create a second bedroom. The core separates public and private space without wasting square footage on single-use corridors — every space serves a meaningful purpose for small dwelling living.
In the standard rectangular configuration, an open living and dining room occupies one side of the core, with a single bedroom on the other. A generous galley kitchen allows passage around the core on one narrow side, while an entry with bench or desk provides access on the opposite side.
Alternate configurations such as the square plan and engaged core can be as compact as 460 gross square feet, or potentially smaller. The prototype is also easily adaptable to larger sizes should zoning limits change. As a flexible granny flat builder solution, Core ADU is designed as a detached dwelling but can be adapted as an attached second unit with an indoor connection to the primary dwelling.
Key spatial features include:
- A generous living and dining room with high ceilings opening to a covered patio
- An age-friendly, accessible kitchen
- A long, adaptable storage wall and optional closet/bench
- Private covered outdoor patio with garden access
- Primary entrance approach from the street
Building Performance, Materials, and Zoning Compliance
Core ADU is constructed using advanced wood framing techniques, which increase energy efficiency, reduce material use, and minimize construction waste. The building is sealed to a tightness of 400 CFM50 plus 100 CFM50 per 1,000 square feet of floor area, as measured by a certified HERS rater, and includes an ERV system with high-velocity HVAC. All appliances are Energy Star rated, and with certain upgrades, the Core ADU can achieve net-zero energy use and be built to Passivhaus standards.
The standard plan features a concrete slab-on-grade floor, with an optional hydronic in-floor heating system available for improved comfort and indoor air quality. The shed roof is designed to accept a solar PV array, though other roof forms are possible to reduce height or conform to neighborhood design standards.
Interior finishes are selected for sustainability and modern appeal. The core is clad in clear-sealed plywood or wood veneer paneling, while the storage wall and closet are finished with durable, colored lacquer. All materials and finishes are zero-VOC rated. Siding is painted fiber cement, though other materials are possible.
As an ADU contractor solution serving the Omaha, Nebraska market, Core ADU complies with all applicable Omaha Zoning Ordinances and building codes. The design has been tested across approximately 256 unique lot types identified in Omaha, including single and double-width lots, corner lots, and properties with street or alley access — making it one of the most adaptable backyard cottage builder solutions available in the region.