This Technical Bulletin provides guidance on the requirements for sprinkler protection for accessory dwelling units when the primary residence is not sprinkler-protected.  For additional information regarding Accessory Dwelling Units (ADUs), see Information Bulletin 400.

General

All new residential units require sprinkler protection per the current California Building Standard Codes. However, 2016 California Senate Bill 1069 exempts ADUs compliant with this Senate Bill from sprinkler protection when the primary dwelling unit is not sprinkler protected.  Senate Bill 1069 does require the design to meet all health and safety requirements of the building standards. 

Detached ADUs

Detached ADUs are only exempt from sprinkler protection when the primary dwelling unit is not sprinkler protected, and the detached ADU(s) is considered a Group R-3 occupancy. See Information Bulletin 125 for how to classify a building as a Group R-3 occupancy.  For duplexes and multiple dwelling unit (MDU) buildings adding an ADU, the primary dwelling unit is considered the entire duplex or the MDU building.

Attached ADUs

Attached ADUs always require sprinkler protection when the primary dwelling unit is sprinkler-protected. The following attached ADU designs do not require sprinkler protection when the primary dwelling unit is not sprinkler protected:

1. One ADU attached to a single-family home.
2. One ADU attached to a duplex (two-family dwelling) created by converting existing, permitted space.  Although this project is a change of occupancy from a Group R-3 to a Group R-2, California Existing Building Code (CEBC), Section 506.1 allows for a change of occupancy without compliance with all of the requirements of the code for the new occupancy when the new use is less hazardous.
3. Up to two ADUs attached to an MDU created by converting the existing permitted space.  As there is no occupancy change and no fire area increase, sprinklers are not required.
4. When three or more ADUs attached to an MDU are created by converting the existing permitted space, the designer must determine what edition the existing building was constructed based upon. DSD will review the existing building code to determine if sprinklers are required based upon the existing building code’s requirements for sprinkler protection and the number of residential units in the structure.

Documents Referenced in this Technical Bulletin

• California Existing Building Code - (CEBC)
• California Fire Code- (CFC)
• Information Bulletin 125- (Residential Building Permits: Group R-2 vs. Group R-3)
• Information Bulletin 400- (Accessory Dwelling Units and Junior Accessory Dwelling Units)