NFPA 13, Standard for the Installation of Sprinkler Systems (2019 edition), consolidated and updated its guidance regarding the need for automatic sprinklers in concealed spaces.
Section 9.2.1 Concealed Spaces Not Requiring Sprinkler Protection details several situations and conditions where automatic sprinklers can be omitted per the Standard.
The previous 2016 edition of NFPA had this guidance mostly in Chapter 8 (Section 8.15 Special Situations) with additional information in a few other chapters/sections of the standard.
In most cases, the construction materials of the concealed space must be noncombustible or of limited combustible content AND combustible loading in the space must be limited at worst.
The definitions of "limited-combustible construction" and "minimal combustible loading" are not fully explained in the standard and often require engineering judgment or interpretation. Each situation should be evaluated on a case-by-case basis during the construction phase rather than afterwards when it will be much more expensive to retrofit sprinklers into an existing building/space.
Section 9.2.2 Spaces Under Ground Floors, Exterior Docks, and Platforms covers concealed spaces below grade, exterior dock and platform areas. In this case, the type of construction (combustible vs. noncombustible) does not come into play. Four required conditions must be met in order to avoid the need for sprinklers in these concealed spaces; (1) the space must not be accessible for storage purposes and is protected against wind-blown debris; (2) the space does not contain any equipment such as conveyors or fuel-fire heating units; (3) the floor over the space is of tight construction so that combustible items can't fall and accumulate below and; (4) no combustible or flammable liquids or materials are processed, handled or stored on the floor above the space.
Section 9.2.3 Exterior Projections provides guidance when automatic sprinklers can be omitted below exterior projects such as canopies, balconies, porte-cocheres, decks and other similar projections. Combustibility of construction materials and the width of the projections are critical factors in these spaces.
The remainder of Section 9.2 deals with other concealed spaces as well as limited area enclosures (closets, pantries, etc.) that may not require sprinkler protection under certain circumstances.
Risk Logic can help you determine if automatic sprinkler protection is required in the concealed spaces at your facility and if so, we can help provide the required design specifications. Please contact us for additional information.
- NFPA Standard 13 (2016 and 2019 editions), Standard for the Installation of Sprinkler Systems