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Understanding Accessory Dwelling Units (ADUs)

Everything you need to know about ADUs in California and Placer County—and how we can help you build one.

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What is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. Also known as a granny flat, in-law unit, backyard cottage, or casita, an ADU is a complete, independent living space with its own kitchen, bathroom, and sleeping area.

ADUs can be attached to the main house, detached as a separate structure, or even converted from existing spaces like garages or basements. They provide flexible living solutions while maximizing the use of your property.

Types of ADUs

Detached ADU

A separate structure in your backyard with complete privacy and independence.

Attached ADU

Connected to your main home, often as an addition or wing with a separate entrance.

Conversion ADU

Converting existing spaces like garages, basements, or attics into living units.

Common Uses for ADUs

Multi-Generational Living

House aging parents or adult children while maintaining privacy and independence for everyone.

Rental Income

Generate passive income through long-term or short-term rentals to offset mortgage costs.

Home Office or Studio

Create a dedicated workspace separate from your home for better work-life balance.

Guest House

Provide comfortable accommodations for visiting family and friends with their own space.

Caregiver Housing

House a live-in caregiver or medical professional close to those who need assistance.

Increase Property Value

Add significant value to your property with additional livable square footage.

California ADU Laws & Benefits

California has some of the most progressive ADU laws in the nation, making it easier than ever to add an accessory dwelling unit to your property. The state has streamlined regulations to encourage ADU development and address the housing shortage.

Key California ADU Benefits

Ministerial Approval

Most ADUs are approved ministerially (no discretionary review), speeding up the permitting process significantly.

No Additional Parking Required

In many cases, ADUs don't require additional parking spaces, especially if near public transit or in historic districts.

Reduced Impact Fees

ADUs under 750 sq ft are exempt from impact fees, and larger ADUs receive proportional reductions.

Owner-Occupancy Flexibility

As of 2025, owner-occupancy requirements have been lifted in many jurisdictions, allowing more flexibility.

Size Allowances

California allows ADUs up to 1,200 sq ft (depending on lot size and local regulations), plus JADUs (Junior ADUs) up to 500 sq ft.

Important: While California law provides a framework, local jurisdictions can have additional requirements. Always check with local planning departments—we can help navigate these requirements for you.

Placer County ADU Regulations

Placer County follows California state ADU laws while implementing specific local guidelines. Here's what you need to know about building an ADU in Placer County:

Placer County Requirements

Size Requirements

  • Detached ADUs: Up to 1,200 sq ft for properties with an existing home
  • Attached ADUs: Can be up to 50% of the existing primary dwelling or 1,200 sq ft, whichever is less
  • Height Limits: Generally 16 feet for detached ADUs (may vary by zone)

Setback Requirements

  • Minimum 4-foot side and rear setbacks for new construction
  • Existing structures being converted may maintain current setbacks
  • Fire safety clearances may require additional setbacks in certain areas

Lot Coverage & Location

  • ADUs must be located on properties with existing or proposed single-family homes
  • Total lot coverage limits still apply (varies by zoning district)
  • Must maintain adequate fire access and emergency vehicle clearance

Utilities & Services

  • Must connect to existing or proposed utilities (water, sewer, electric)
  • Separate utility meters may be required for rental ADUs
  • Fire sprinklers required in some areas (particularly in wildfire zones)

Special Considerations for Truckee & Lake Tahoe Area

The Truckee and Lake Tahoe areas may have additional requirements due to environmental protections (TRPA regulations), wildfire safety zones, and alpine building codes. Snow load requirements, wildfire defensible space, and Tahoe Regional Planning Agency (TRPA) coverage limits may apply. We have extensive experience navigating these unique requirements.

Disclaimer: This information is a general overview and subject to change. Specific requirements vary by location, zoning, and project details. We recommend scheduling a consultation where we'll conduct a thorough site evaluation and review current regulations specific to your property.

ADU bedroom with quality finishes and modern design

Why Choose NestMade for Your ADU?

Understanding ADU regulations is just the beginning. Building a quality ADU requires expertise, attention to detail, and a proven process—exactly what we bring from 20 years of luxury construction.

Expert Permit Navigation

We handle all permitting, zoning approvals, and regulatory compliance so you don't have to worry about the details.

Local Expertise

12 years building in Truckee means we understand Placer County requirements and Tahoe-specific regulations.

Luxury Home Quality

The same craftsmanship and attention to detail from our 30+ custom homes applied to your ADU.

Transparent Process

Clear communication on pricing, timeline, and progress throughout your entire project.

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