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ADU Design Ideas for Greater Housing Choice

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House Review

ADU Design Ideas for Greater Housing Choice

Accessory dwelling units are making a comeback and diversifying affordable housing options. These house plans offer imaginative, purposeful ADU designs

By Larry W. Garnett, FAIBD, House Review Lead Designer June 2, 2022
Smart ADU design
Kevin L. Crook Architect's Smart ADU design. Scroll down to find out more about the design. | Rendering: courtesy Kevin L. Crook Architect
This article first appeared in the May/June 2022 issue of Pro Builder.

An accessory dwelling unit (ADU) is a relatively new term for a very old idea. Essentially an additional living unit that is legally part of the same property as the main house, these structures range from detached small cottages to living quarters above a garage.

Garage apartments, or carriage houses, as they were often called, can be found in many neighborhoods developed as far back as the early 20th century, before losing popularity and being prohibited in many areas in the current century.

Ironically, the reason they were prohibited is actually the motivation for today’s ADU revival: rental housing and income. While rental properties of any kind may still cause a NIMBY stir, the lifestyle and financial value ADUs can provide is undeniable; having a parent, older child, friend, or caregiver within such close proximity can be life-changing.

From a community and neighborhood perspective, rental ADUs offer a housing choice for people who would rather live in a quaint cottage or secluded quarters above a garage, a theme displayed in the diverse, imaginative, and purposeful ADUs offered here by the House Review design team.


Peace River Estate Homes

ARCHITECT: Donald F. Evans, AIA, The Evans Group, dmichele@theevansgroup.com, 407.650.8770


Plan A: Width: 39 feet / Depth: 28 feet, 4 inches / Living area: 1,071 sf

Plan B: Width: 32 feet / Depth: 19 feet / Living area: 608 sf

Some lots warrant a detached garage but local zoning doesn’t allow more than one structure in addition to the main house. And sometimes there isn’t enough room on the lot for another structure. Oftentimes, an ADU over the garage makes the most sense.

For Plan A, the intent was a complete guest house for the owner’s aging father; as such, it includes an elevator. The location of the home affords 180-degree water views and enjoys river breezes, capitalized on by the large outdoor veranda and barbecue area. In addition, the rooms are far nicer and more spacious than most apartments in the area.

Plan B was designed as a guest room for an occasional visiting family member as well as a separate home office for the owners and/or a place for their college-aged sons to hang out with friends. It also provides a seasonal storage area and features a wet bar/kitchenette and open floor plan.

ADU design Peace River Estate, Plan A


ADU design Peace River Estate, Plan A, floor plan

Plan A

A. Elevator for accessibility/aging in place

B. Multipurpose veranda optimizes views

C. Generous, well-appointed rooms

D. Ample storage


ADU design Peace River Estate, Plan B


ADU design Peace River Estate, Plan B, floor plan

Plan B

E. Open plan for multiple uses

F. Wet bar/kitchenette

G. Seasonal/extra storage

Smart ADUs

ARCHITECT: Jeff Addison, Kevin L. Crook Architect, jaddison@klcarch.com, 949.660.1587

DIMENSIONS: Width: 25 feet, 6 inches / Depth: 20 feet, 6 inches / Living area: 496 sf


Located in a suburban setting on conventional front-loaded lots, these ADUs are designed and located for privacy and efficiency.

Each 80-by-90-foot lot accommodates two primary homes, each with an ADU in back. The primary homes are mirrored floor plans, with a common driveway between them to access the ADUs at the rear of the lot, which have their own dedicated parking spaces.

Each primary home enjoys a private yard defined by a blank wall of the ADU unit, while the ADUs also have an outdoor area off their living rooms for entertaining and pets.

The efficient 496-square-foot ADUs feature a front porch, open floor plan, full bedroom, a common bathroom, and a laundry closet.

ADU design, Smart ADU exterior



B. ADU outdoor area

C. ADU dedicated parking

D. Primary home

E. Primary home outdoor area

F. Common driveway

Smart ADU floor plan


Smart ADU and primary house floor plan



DESIGNER: Larry W. Garnett, FAIBD, larrygarnett@larrygarnettdesigns.com, 254.205.2597

DIMENSIONS: Width: 16 feet / Depth: 42 feet / Living area: 595 sf


This one-bedroom ADU design offers plenty of natural light and privacy in 595 square feet. While it’s ideal for an aging parent, it could also be a short-term space for an older child.

Depending on local ordinances, it may be a lucrative rental property, appealing to single tenants or those seeking short-term stays in close proximity to a tourist attraction.

CT-3 design for ADU, floor plan


A. Clerestory windows along the side provide natural light and privacy

B. Compact kitchen

C. Generous bedroom

D. Built-in window seat with storage cabinets and open shelves

E. Bath with stackable laundry unit and zero-threshold shower

F. Spacious entry porch has room for seating

G. Small side yard leads to main house


CT-3 design for ADU, exterior rendering


CT-3 design for ADU, exterior

Ridgegate Plan 2

DESIGNER: Seth Hart, DTJ Design, shart@dtjdesign.com, 303.443.7533

DIMENSIONS: Width: 13 feet, 9 inches / Depth: 17 feet, 5 inches / Living area: 625 sf


One of two new plans in an alley-loaded series of homes that offer optional ADUs in a new Colorado development, this floor plan provides great flexibility as an upgrade to the base floor plan as either a rental income generator or a private guest suite.

The base plan has an oversized two-car garage. If the owners add an ADU, a walled-off third car bay is provided for dedicated parking for the accessory unit.

Access to the ADU is off the alley, which maintains privacy from the primary residence.

The second-floor unit provides one bedroom, a stacked washer/dryer, a compact kitchen, and a small balcony.

Ridgegate Plan 2 ADU design, exterior


A. Private third-car garage provides dedicated parking with direct access to ADU

B. Entrance off alley maintains privacy from primary residence

C. High windows at courtyard admit natural light to stair and living area while maintaining privacy

D. Small balcony provides outdoor living, with options to expand for end lots


Ridgegate Plan 2 ADU design, first-floor plan


Ridgegate Plan 2 ADU design, second-floor plan


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