What is an accessory dwelling unit?

An accessory dwelling unit is a secondary housing unit located on a residential lot. ADUs can be attached or detached from a primary residence. They can provide an additional source of income for homeowners, accommodate multigenerational housing and help increase the supply of affordable housing. A junior accessory dwelling unit is an ADU created within the walls of a proposed or existing single-family home and may be no larger than 500 square feet.

What are the required development standards (setbacks, height, square footage, etc.)?

All current development standards and processing requirements are summarized in the ADU Information Bulletin.

How much does it cost to permit and build an ADU in Carlsbad?

Permitting fees to construct most accessory dwelling units cost approximately $2,000 to $4,000 and depend on the square footage of the unit. Fee costs are outlined in the Master Fee Schedule FY 2024-25. Construction costs for an ADU can be anywhere from $10,000 for a simple bedroom conversion to $300,000 for a higher‐end companion unit.

Many ADUs are exempt from impact fees due to not meeting the square footage threshold requirement.

Accessory Dwelling Unit Permit Ready Program (preapproved ADU building plans)

In accordance with the city’s Housing Element Program 1.2, the city is offering free pre-approved ADU building plans that provide a variety of options in terms of size, type and style. These preapproved plans are intended to encourage the development of accessory dwelling units by saving homeowners three to six months of planning and design time and the approximately $8,000-$16,000 in private architectural design fees associated with preparing ADU building plans. For more information, please visit the ADU Permit Ready Program webpage.