Accessory Home 101

How to get started

Considering building an accessory home on your property? Placer County is here to assist you with the process. There are geneimage of constructionrally four steps to building an accessory home:

  • Kickoff - Determine if your property is a good candidate for an accessory home, check your well and septic capacity, and set your budget or secure financing options. Continue to read through this page to learn more.
  • Design - Once you secure an architect/contractor you will start to design your accessory home. You can also select from free plans provided by Placer County. Learn more
  • Permits - You will be issued permits to start construction. The number and types of permits needed for an accessory home may vary. Public utility permits/use fees are waived for qualified accessory homes. Learn more
  • Construction - When you have your building permits, you can start the construction of your accessory home. The builder you hire will lead this step.  Learn more

What you need to know

  1. Size
  2. Parking
  3. Building Permits
  4. Utility Connections
  • An accessory home is intended to be secondary in size to the primary home. 
  • An accessory home that is attached to a primary dwelling may be up to 50% of the existing unit. 
  • An accessory home that is detached from the primary home may be up to 1,200 square feet, regardless of the size of the primary structure.      
  • There is no minimum lot size for an accessory home, but adequate water and sewer or septic must be demonstrated.

Securing financing

It is also important to consider how you will pay for the permitting and construction of your accessory home. There are a handful of financing options including:AH Financing

  • Cash savings/other liquid assets 
  • Cash-out refinance 
  • Loans from friends/family 
  • Home equity loan or home equity line of credit 
  • Renovation loans 

The cost of building an Accessory Home varies. To get a sense of how much your home might cost, take a look at the County’s Accessory Home Calculator.

NEW fee reductions for accessory homes

No impact fees will be assessed for units less than 750 square feet. For a unit that is 750 square feet or more, the impact fees are proportional to the primary unit. On average, you can save $20,000 in government fees when you build an ADU (plus $6,000-$10,000 if you choose from our free plans).

Accessory Home SizePrimary Dwelling SizeImpact Fees  

499 square feet or less

No impact fees

500 to 749 square feet

No impact fees*

750 square feet

1,500 square feet

(750/1500)*100% = 50% impact fees

800 square feet

2,400 square feet

(800/2400)*100% = 33.33% impact fees

1,200 square feet

2,400 square feet

(1200/2400)*100% = 50% impact fees

1,200 square feet
4,800 square feet

(1200/4800)*100% = 25% impact fees

Impact fees are applied to accessory homes 750 square feet and greater up to 1,200 square feet. The square footage of the accessory home is compared to the square footage of the primary dwelling. To determine your impact fees take the square footage of your accessory home and divide that by the square footage of your primary dwelling then multiply by 100% and that will give you your percentage of impact fees. 

*School fees still apply to accessory homes that are between 500 and 749 square feet. School fees vary in each school district and are administered based on the square footage of the intended residential building. 

Building accessory homes in Tahoe

ADUs are allowed on parcels zoned for residential use in the Placer County portion of the Tahoe Basin and are subject to additional regulations per Tahoe Regional Planning Agency (TRPA). Learn more here.