Everything You Need to Know

About Building an ADU

ADCON have compiled answers to some of the most frequently asked questions about our construction and remodeling services.

What Is an ADU?

An ADU is a secondary residential unit built on the same lot as an existing home. It includes its own kitchen, bathroom, living area, and sleeping space.

Common uses include:

  • Rental income

  • Housing for aging parents

  • Guest accommodations

  • Home office

  • Housing for adult children

  • Caregiver quarters

Types of ADUs

Detached ADU

A completely separate structure built in the backyard.

Advantages

  • Maximum privacy

  • Excellent rental potential

  • Flexible design

Attached ADU

Built as an addition connected to the existing home.

Advantages

  • Lower utility connection costs

  • Easier access

  • Efficient use of available space

Garage Conversion

Transforms an existing garage into a livable space.

Advantages

  • Often lower construction costs

  • Faster construction

  • Uses the existing building footprint

Basement Conversion

Converts unused basement space into an independent living unit.

Benefits of Building an ADU

Generate Rental Income

Many homeowners use ADUs to create long-term rental income that helps offset mortgage payments.

Increase Property Value

A professionally designed ADU can significantly increase a home's market value and appeal.

Flexible Living Space

ADUs can adapt to changing family needs, providing space for relatives, guests, or a home office.

Aging in Place

Many families build ADUs so parents or grandparents can live nearby while maintaining independence

Step 1: Initial Consultation

Discuss your goals, budget, and property conditions.

Step 2: Site Evaluation

A contractor evaluates:

  • Existing structures

  • Property access

  • Utilities

  • Topography

  • Zoning considerations

Step 3: Design

The design phase includes:

  • Floor plans

  • Exterior elevations

  • Material selections

  • Structural planning

  • Energy efficiency considerations

Step 4: Permit Approval

Permit requirements vary depending on the project and local regulations. Your contractor prepares and submits the necessary documents and coordinates with the appropriate agencies.

Step 5: Construction

Construction typically includes:

  • Site preparation

  • Foundation

  • Framing

  • Roofing

  • Plumbing

  • Electrical

  • HVAC

  • Insulation

  • Drywall

  • Cabinets

  • Flooring

  • Painting

  • Final inspections

Typical ADU Construction Process

How Long Does an ADU Take?

Several factors influence the overall cost:

  • Size

  • Type of ADU

  • Site conditions

  • Foundation requirements

  • Utility connections

  • Interior finishes

  • Structural work

  • Custom features

Because every property is different, obtaining a personalized estimate is the best way to understand your project's investment.

What Affects ADU Costs?

While every project is unique, the timeline depends on:

  • Design complexity

  • Permit approvals

  • Site conditions

  • Material availability

  • Construction scope

Working with an experienced contractor can help keep the project organized and minimize delays.

Many homeowners prioritize:

  • Open floor plans

  • Large windows for natural light

  • High ceilings where feasible

  • Energy-efficient windows and insulation

  • Durable, low-maintenance materials

  • Smart storage solutions

  • Outdoor living space

Good design helps maximize comfort, functionality, and long-term value.

Design Tips

Common Mistakes to Avoid

  • Choosing a contractor based only on the lowest price

  • Beginning work before permits are secured

  • Underestimating site preparation needs

  • Selecting finishes without considering durability

  • Making major design changes during construction

  • Failing to plan for utility connections

Planning carefully from the beginning can reduce costly changes later.

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