K-Factor and Temp. to Protect Steel Columns?

8/28/2025

For the protection of steel columns using sidewall sprinklers, what is the k-factor and temperature rating needed?

The existing upright sprinklers for the high-piled storage are 286°F. I couldn't find information for this in NFPA 13 2022. Any help or advice would be greatly appreciated. Thanks in advance!

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7 Comments

Jon N

8/28/2025 08:38:47 am

This arrangement is likely an alternate method of protection to get out of fire-resistive-rated coatings on the steel structural members. As such, it is outside of the scope of NFPA 13.

You might find some guidance in other NFPA standards - like for exposure protection or protecting steel items (such as tanks).

Dan Wilder

8/28/2025 08:57:40 am

In the past, we have provided either the same temp or one temp level below, but not below 200°F. K-Factor is based on the discharge requirements being met (typically the surface areas being covered x Density) and I have used 5.6K & 8.0K sprinklers in the past.

The general section of the Storage chapters (13-19' Ed falls under 20.15)

Rich G

8/28/2025 09:56:39 am

Typically Column and Structural protection falls under NFPA 15, Orifice size can vary down to very small as your just protecting surface area of the column, but be wary any K-factor below 1/4" would require a strainer at your water supply. Temp if not an open head system would depend on your hazard and ambient temperatures.

Glenn Berger

8/28/2025 12:03:49 pm

My experience has been exactly what Dan stated above . Just add two sprinklers per column spraying into the web space.

Franck

8/28/2025 01:34:12 pm

You can also find some info in FM Global data sheet, such as maybe the one for turbines (for pedestal of lube oil tanks) in 7-101

Todd E Wyatt

8/29/2025 01:49:54 pm

The fire-resistance rating (FRR) of building elements (e.g. Columns & Beams) shall be determined by (1) of (3) methods as required by the scoping Code (e.g. IBC-2024):
1. TESTED ASSEMBLIES
2. ANALYTICAL METHODS
3. APPROVED ALTERNATE METHOD

I am unaware of TESTED ASSEMBLIES or ANALYTICAL METHODS that would be accepted by an AHJ to substitute the passive FRR of building elements with the active automatic sprinkler system (ASPS) so that leaves APPROVED ALTERNATE METHOD (AAM). The AAM requires approval by the AHJ.

REFERENCES
Section 703 Fire-Resistance Ratings and Fire Tests
703.1 Scope
703.2 Fire Resistance
The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with Section 703.2.1 or 703.2.2 WITHOUT THE USE OF AUTOMATIC SPRINKLERS OR ANY OTHER FIRE SUPPRESSION SYSTEM BEING INCORPORATED, or in accordance with Section 703.2.3.

703.2.1 TESTED ASSEMBLIES
A fire-resistance rating of building elements, components or assemblies shall be determined by the test procedures set forth in ASTM E119 or UL 263. The fire-resistance rating of penetrations and fire-resistant joint systems shall be determined in accordance with Sections 714 and 715, respectively.
703.2.2 ANALYTICAL METHODS
The fire resistance of building elements, components or assemblies established by an analytical method shall be by any of the methods listed in this section, based on the fire exposure and acceptance criteria specified in ASTM E119 or UL 263.
1. Fire-resistance designs documented in approved sources.
2. Prescriptive designs of fire-resistance-rated building elements, components or assemblies as prescribed in Section 721.
3. Calculations in accordance with Section 722.
4. Engineering analysis based on a comparison of building element, component or assemblies designs having fire-resistance ratings as determined by the test procedures set forth in ASTM E119 or UL 263.
5. Fire-resistance designs certified by an approved agency.
703.2.3 APPROVED ALTERNATE METHOD
The fire resistance of building elements, components or assemblies not complying with Section 703.2.1 or 703.2.2 shall be permitted to be established by an alternative protection method in accordance with SECTION 104.2.3.

Section 104 Duties and Powers of Building Official
104.2.3 Alternative Materials, Design and Methods of Construction and Equipment
The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative is not specifically prohibited by this code and has been approved.
Exception: Performance-based alternative materials, designs or methods of construction and equipment complying with the International Code Council Performance Code. This exception shall not apply to alternative structural materials or to alternative structural designs.
104.2.3.1 Approval Authority
104.2.3.2 Application and Disposition
104.2.3.3 Compliance With Code Intent
104.2.3.4 Equivalency Criteria

See article : Assessing the reliance of sprinklers for active protection of structures

Jack G

9/21/2025 11:15:51 am

I am assuming you are only talking about the columns that fall in the racks and not every column.
Falls into NFPA 13, and my experience is that it’s 200 degree range / intermediate if roof at 286.

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K-Factor and Temp. to Protect Steel Columns?

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