The Advantages and Types of ADUs

November 17, 2025

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Building an accessory dwelling unit (ADU) is a practical way to expand living space without the expense or disruption of a conventional room addition. Many property owners create these small, independent dwellings for rental income or to host family members comfortably on the same property.

Interest in ADUs continues to grow across Colorado as communities look for flexible, efficient housing options. Knowing the main ADU types and their advantages helps you decide which design best fits your goals and property.

What Is an ADU?

An accessory dwelling unit, often called a secondary or backyard home, is an independent living space built on the same property as the main structure. It includes the essential elements of a small residence, such as a kitchen, bathroom, and sleeping area.

ADUs meet building codes for permanent housing and provide a comfortable, private living environment for long-term occupants.

These spaces can serve many functions. Homeowners may build them to house family members, rent them for supplemental income, or convert underused areas into self-contained apartments. 

Common ADU Types

The design and layout of an ADU can vary depending on lot size and zoning conditions, as well as the structure of the main home. Each option offers benefits that meet different property needs. 

Detached ADU

A detached ADU stands apart from the primary home. It is often designed as a small cottage or standalone structure that includes all the features of an independent residence. 

The main advantage of this type is privacy for both the occupants of the main home and the ADU. A detached design allows for complete separation from the main living space while maintaining visual harmony through coordinated architecture and landscaping. It also provides the most flexibility for future use, whether as long-term housing or a rental property.

Attached ADU

An attached ADU shares one or more walls with the main home but has its own entry, kitchen, and bathroom. Because it connects to the existing structure, it uses shared utilities and framing, which reduces construction costs. This type works well for family members who prefer to live nearby but keep their privacy.

Garage Conversion ADU

Many property owners choose to convert an existing garage into a functional living unit. This option uses the existing foundation and structure, which reduces material costs and construction time. 

A garage conversion works exceptionally well for smaller lots or urban neighborhoods where adding a new building might not be feasible. With careful design, these conversions can have efficient layouts and modern amenities that rival larger dwellings.

Basement or Interior Conversion ADU

A basement or interior conversion turns unused space into a comfortable, independent apartment. These projects usually include new insulation and updated utility lines to meet current codes, but do not require exterior construction. Many homeowners choose this type of ADU to accommodate family or create a home office.

Above-Garage ADU

Building a new living space above an existing or new garage makes excellent use of vertical space. This type of ADU preserves yard areas for recreation or landscaping while adding livable square footage. It often provides better views and stronger natural light than ground-level options. Above-garage ADUs work well for homes with narrow lots where open ground space is limited. 

Commercial or Mixed-Use Adaptations

In commercial or mixed-use settings, the same principles apply. Property owners can add living units above or behind retail or office spaces. These designs create on-site accommodations for caretakers or short-term tenants while improving property value. 

Sun Mountain Design Group’s commercial experience allows our team to apply ADU strategies to small business properties where flexible use and efficiency are essential.

Advantages of Building an ADU

Beyond creating more livable space, building an ADU offers both functional and financial benefits.

  • Property Value: A well-designed ADU can increase a property’s market appeal. Buyers appreciate the potential for rental income or multi-generational living, which can raise resale value.
  • Flexibility: An ADU supports many uses over time. For instance, a unit that was originally meant to serve as a guest suite can later become a rental or private studio.
  • Efficient Land Use: By building on existing lots, ADUs make better use of developed areas. They allow homeowners to grow within their current neighborhoods rather than relocating.
  • Sustainability: ADUs encourage smaller living spaces with lower energy demands. Shared infrastructure, such as driveways, landscaping, and utilities, also reduces material use. 
  • Design Potential: With careful planning, an ADU can complement the architecture of the main structure and blend naturally with the site. Our team designs each project to balance aesthetics and functionality while complying with local regulations.

Explore the Potential of ADUs With Sun Mountain Design Group

Whether your project is a detached cottage, a garage conversion, or an interior remodel, you can trust Sun Mountain Design Group to deliver the results you envision. 

We are a trusted design-build firm based in Colorado Springs, with over 50 years of experience in residential, commercial, and civil projects. From early concepts to construction coordination, our team supports every phase of the process. Contact us today to start planning an ADU that adds value to your property.

 

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