FM Global Requirements for Skylights?

3/17/2023

Does FM Global design criteria weigh in on whether skylights require protection?

Do they simply adopt the same provisions in NFPA 13 in this regard? Or is there some devation?

I can't see any allowance for omission of sprinkler protection for skylights in Data Sheet 2-0.

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6 Comments

Pete H

3/17/2023 07:44:26 am

FM Global does not have a provision for an omission like NFPA 13 for skylights.

They have guidance on how to handle skylights around Figures 2.5.1.3.4(a) and 2.5.1.3.4(b) [Based on 2021 edition of FM 2-0] for plastic skylight protection.

3/17/2023 08:21:39 am

FM Global never defers to NFPA. If it is not in their standard then they don't allow it. Another good example of this is the Small Room Rule.

Jesse

3/17/2023 09:49:03 am

FM is a standalone standard and never defers to NFPA. Short of Affiliated FM / FM Global, most insurers like most AHJs use NFPA and then use FM where NFPA is silent - like Rolled Carpet in 2016 NFPA 13.

In your case, FM does not allow for omission under a skylight like NFPA 13 does. So, you still see a lot of Storage and Manufacturing facilities that were protected under FM that have these.

Todd E Wyatt

3/17/2023 10:29:53 am

As others have stated, the adopted, scoping Code(s) (e.g. 2021 IBC, NFPA 101) determine WHERE automatic sprinkler systems (ASPS) are required and their referenced standards (e.g. NFPA 13) explain HOW the required ASPS is to be designed, installed, inspected, and maintained.

The scoping Code (2021 IBC) does NOT reference “SKYLIGHT” in “Chapter 9 Fire Protection and Life Safety Systems, Section 903 Automatic Sprinkler Systems, 903.2 Where Required.”
“AUTOMATIC SPRINKLER SYSTEM” is NOT referenced in “Chapter 24 Glass and Glazing” which references “SKYLIGHT” (31) times in this 2021 IBC chapter. See “Section 2405 Sloped Glazing and Skylights”

2019 NFPA 13 is the “referenced standard” for ASPS per the 2021 IBC.
2019 NFPA 13 references “SKYLIGHT(S)” (12) times (see REFERENCES).
Paragraph 9.3.16.1 permits the omission of sprinklers from skylights that do not exceed 32 ft2 in area and are separated from any adjacent unprotected ceiling pocket or skylight.

REFERENCES
2019 NFPA 13

Chapter 9 Sprinkler Location Requirements
Chapter 9 covers the general requirements for the location of sprinklers applicable to all the various types, with consideration for the impact of building construction features and equipment on satisfactory sprinkler system performance. Also covered in this chapter are allowances for the omission of sprinklers and protection for special situations, the use of sprinklers and the allowable areas per sprinkler, and spacing limitations.
REORGANIZATION NOTE
The new Chapter 9, which comprises certain sections from Chapter 8 of the 2016 edition, contains the general requirements and allowances for all sprinklers related to the specific locations in which sprinklers are required to be installed. The sections involved in the reorganization of this chapter include the following:
A consolidated list of specific locations where sprinklers can be omitted has been developed into Section 9.2 to compile all the specific allowances that were previously scattered throughout Chapter 8 in the 2016 edition.
The requirements for special situations have been consolidated into Section 9.3 to combine provisions previously spread throughout Chapter 8 of the 2016 edition into one location.
The general requirements for the usage of sprinklers from Section 8.3 in the 2016 edition have been incorporated into the new Section 9.4.
The general requirements for the position, location, and spacing for sprinklers in Section 8.3 of the 2016 edition have been incorporated into the new Section 9.5.

9.2 Allowable Sprinkler Omission Locations.
ENHANCED CONTENT
Section 9.2 contains a consolidated list of specific locations where sprinklers can be omitted. It was developed to consolidate all the specific allowances that were scattered throughout Chapter 8 of the 2016 edition.
Section 9.2 can be expected to be a very active part of NFPA 13 during future revision cycles. It is the one section where the basic principle of NFPA 13 — that sprinklers must be installed throughout the premises — is allowed to be altered. During each code development cycle, the Technical Committee on Sprinkler System Installation acts on inputs and comments seeking to “excuse” a specific portion of a building from the requirements of sprinkler protection due to a special situation. The case is typically made that, under certain conditions, the presence of sprinklers does not provide any greater protection, and the omission of sprinklers in these specific areas and spaces within a building should be permitted. (Section 9.3 identifies those spaces and conditions.)
It is important to note the following two points regarding Section 9.2:
1. It is imperative that when the elimination of sprinklers from a space based on this section is being considered, the space must comply exactly with the description and requirements found within the applicable paragraph(s). In other words, any deviation from the description in the applicable paragraph negates its application, and, as a result, the space must be sprinklered.
2. If a space is not specifically detailed in this section, it is intended to be protected by sprinklers under 9.1.1(1).

9.2.17 SKYLIGHT.
Sprinklers shall not be required in SKYLIGHTS complying with 9.3.16.
9.2.17.1
SKYLIGHTS that allow venting, other than smoke and heat venting per 20.6.5, shall be provided with sprinkler protection installed in the SKYLIGHT.

9.3 Special Situations.
ENHANCED CONTENT
The requirements for special situations have been consolidated into Section 9.3 to consolidate the provisions that were previously spread throughout Chapter 8 of the 2016 edition. The situations addressed in this section do not fit the more usual building configurations such as “rooms” or “compartments.” Instead they are often referred to as “spaces,” and provisions are provided to clarify where the required

Todd E Wyatt

3/17/2023 10:31:04 am

REFERENCES continued ...

9.3.16 SKYLIGHTS.
9.3.16.1
Sprinklers shall be permitted to be omitted from SKYLIGHTS not exceeding 32 ft2 (3.0 m2) in area, regardless of hazard classification, that are separated by at least 10 ft (3.0 m) horizontally from any other unprotected SKYLIGHTS or unprotected ceiling pocket.
9.3.16.1.1
When a sprinkler is installed directly beneath a SKYLIGHT not exceeding 32 ft2 (3.0 m2), the distance to the ceiling shall be measured to the plane of the ceiling as if the SKYLIGHTS was not present.
9.3.16.2
SKYLIGHTS not exceeding 32 ft2 (3.0 m2) shall be permitted to have a plastic cover.
ENHANCED CONTENT
Paragraph 9.3.16.1 permits the omission of sprinklers from skylights that do not exceed 32 ft2 (3.0 m2) in area and are separated from any adjacent unprotected ceiling pocket or skylight. A single small skylight should not have a significant impact on performance, and the requirement for a 10 ft (3.0 m) separation between unprotected ceiling pockets and skylights ensures that there will be a sprinkler between skylights. That sprinkler prevents heat from collecting in multiple adjacent skylights or pockets where sprinkler activation could be delayed (see the exhibit below). The elimination of the sprinkler from under skylights includes skylights that have a plastic cover, since the amount of plastic within small skylights does not add significantly to the fuel load.

9.4.2.5*
The following practices shall be observed to provide sprinklers of other than ordinary-temperature classification unless other temperatures are determined or unless high-temperature sprinklers are used throughout, and temperature selection shall be in accordance with Table 9.4.2.5(a), Table 9.4.2.5(b), Table 9.4.2.5(c), and Figure 9.4.2.5:
(4) Sprinklers under glass or plastic SKYLIGHTS exposed to the direct rays of the sun shall be of the intermediate-temperature classification.

Table 9.4.2.5(b) Temperature Ratings of Sprinklers in Specified Locations
Location SKYLIGHTS
Ordinary-Temperature Rating : Glass or plastic
Intermediate-Temperature Rating : Glass or plastic
High-Temperature Rating : Glass or plastic

Franck Orset

3/17/2023 11:21:03 am

The only time when FM refer to NFPA (they sometimes do), is when their data sheet is with an N (for NFPA).
In that case, they apply NFPA standard with specific deviations outlined in the document.

There are several such FM data sheet.

Examples:
4-1N - FIXED WATER SPRAY SYSTEMS FOR FIRE PROTECTION
1.0 SCOPE
FM Global has accepted and adopted NFPA Standard 15, Standard for Water Spray Fixed Systems for Fire
Protection, 2001 Edition.

4-11N CARBON DIOXIDE EXTINGUISHING SYSTEMS
1.0 SCOPE
FM Global has accepted and adopted NFPA 12, Standard for Carbon Dioxide Extinguishing Systems, 2000
Edition. FM Global comments including any differences between the NFPA and FM Global are provided in
the FM Global Interpretation Section.

In the past, there used to be a 2-8N that was based on NFPA 13, but is no longer available and replaced with 2-0 (that is also includes the old 2-2 for ESFR and other documents no longer available).
Note that 2-8 is for sprinklers in earthquake zones and is specific to FM (no reference to NFPA 13 corresponding chapter).

FM Global Requirements for Skylights?

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