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City and County of San Francisco
Department of Building Inspection
London N. Breed, Mayor
Patrick O’Riordan, C.B.O., Director
INFORMATION SHEET
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NO. FS-03
DATE:
CATEGORY:
SUBJECT:
December 6, 2023
Fire Safety
Automatic Sprinkler System Requirements for Additions and Alterations in
Existing Non-Sprinklered R-3 Occupancies with 4-Stories or Resulting in 4-
Stories
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PURPOSE:
REFERENCE:
DISCUSSION:
This information sheet is clarifies the automatic sprinkler system requirements
triggered by additions and alterations in existing three- and four-story R-3
occupancies of Type-V construction.
San Francisco Building Code (SFBC), Current Edition
San Francisco Existing Building Code (SFEBC), Current Edition
California Building Code (CBC), Current Edition
SFBC Section 903.2.8 Automatic Sprinkler Systems, Where Required, Group R
CBC Section 202 Definitions
SFEBC Section 502 Additions
SFEBC Section 503 Alterations
CBC Section 503.1.4 Occupied Roofs
CBC Section 504 Building Height and Number of Stories
CBC Section 903.2.8 Automatic Sprinkler Systems, Where Required, Group R
CBC Section 903.3 Automatic Sprinkler Systems, Installation Requirements
CBC Section 1004.7 Occupant Load, Outdoor Areas
Projects are differentiated between additions, where installation of automatic
sprinkler systems throughout the building may be required, and alterations, where
the automatic sprinkler systems are limited to the area of alteration and may not be
required throughout the building.
Additions: Additions, as defined by CBC 202, is “an extension or increase in floor
area, number of stories or height of a building or structure.” Where additions are
proposed, the entire building shall comply with CBC 504. Reference examples 1
through 4 for additions to R-3 occupancy buildings of Type-V construction where
automatic sprinkler systems are required throughout to satisfy the requirements of
CBC 504:
1. Vertical additions to existing 3-story, non-sprinklered buildings, resulting in
more than three stories.
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Department of Building Inspection — Technical Services Division
49 South Van Ness Avenue, Suite 500 — San Francisco CA 94103
(628) 652-3720 | sfdbi.org
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INFORMATION SHEET IS FS-03
2. Conversion of unoccupied attics to occupiable space in existing 3-story, non-
sprinklered buildings, resulting in more than three stories (converted attics are
considered added stories).
3. Horizontal additions to existing 4-story, non-sprinklered buildings.
4. Excavation of basements to create occupiable space in existing 4-story, non-
sprinklered, buildings.
Alterations: Alterations, as defined by CBC 202, is “any construction or renovation
to an existing structure other than repair or addition.” The areas of alteration shall
comply with current code requirements for new construction, including installation
of automatic fire sprinklers. However, unaltered portions of the existing building
are not required to be upgraded to current code provisions for new construction.
The two examples below illustrate alterations in existing 4-story, R3 occupancies of
Type-V construction, where installation of automatic sprinklers throughout the
entire building is not triggered. Instead, compliance with the current codes for new
construction is limited to the area of alteration.
1. Conversion of existing 1st floor unoccupiable space to occupiable space.
2. Conversion of basements to habitable or occupiable space without excavation.
Other Conditions:
1. For understanding of various conditions, including those not listed in this
information sheet, see the above referenced building code sections.
2. For existing R-3 occupancies with 3 stories or less, see also DBI Information
Sheet EG-03.
3. For new residential decks, including occupiable roofs, see also DBI Information
Sheet EG-01.
trick O’Riordan, C.B.O., Director Date
Department of Building Inspection
This Information Sheet is subject to modification at any time. For the most current version, visit our
website at sfdbi.org.
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Department of Building Inspection — Technical Services Division
49 South Van Ness Avenue, Suite 500 — San Francisco CA 94103
628-652-3720 | sfdbi.org
