Does Combustible Insulation Trigger Sprinklers?

8/24/2022

I'm dealing with a commercial occupancy being a combination of large and smaller shops where automatic sprinklers will be provided.

How do we deal with combustible and limited-combustible thermal insulation to ceilings or soffits?

If the structure is non-combustible, does combustible insulation trigger a need for sprinklers above the ceilings?

I can not put my finger on specifics in NFPA 13 where guidance on thermal insulation is provided. Thanks in advance.

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9 Comments

Peter Howard

8/24/2022 07:05:58 am

I'd say it depends the amount of combustible insulation.

Does it now exceed NFPA 8.15.1.2.1 (2016 edition) requirement of "minimal combustible loading" to omit sprinklers? If so, yes, you have to protect the area.

However the Annex A.8.15.1.2.1 does try to give a bit more leeway, but honestly, if this is fully combustible insulation that's filling the area that is beyond the typical cabling above an office, yeah, you have to protect this combustible loading above the ceiling.

That said, not actually seeing how much insulation is there or the structural design above the ceiling, I can't be that certain of it.

schulman

8/24/2022 08:05:02 am

why are they using combustible insulation !?

Jesse

8/24/2022 08:05:14 am

I agree with Peter. The combustibility of the insulation is the driver. If it exceeds the limits of minimally combustible then yes, it needs to be protected.

That being said, if indeed it surpasses the threshold of limited combustibility, it may be worthwhile to explore other insulating options.

Glenn Berger

8/24/2022 08:06:29 am

Encase the combustible insulation inside non-combustible envelope-type assembly.

Dan Wilder

8/24/2022 08:09:37 am

In 13-19' Edition:

9.2-Allowable Sprinkler Omission Locations
9.2.1.13-Noncombustible concealed spaces having exposed combustible insulation where the heat content of the facing and substrate of the insulation material does not exceed 1000 Btu/ft³ shall not require sprinkler protection.

If the insulation is considered combustible (doesn't meet the above criteria), sprinklers will be required.

Todd E Wyatt

8/24/2022 08:15:07 am

The scoping Code, where an automatic sprinkler system (ASPS) is required, is per the adopted Fire Code (e.g. 2021 IBC/IFC). The referenced standards (NFPA 13) by the scoping Code outlines how the ASPS is to be designed, installed, tested, and maintained.

I recommend reviewing 903.3.1.2.3 Attics per 2021 IBC :

Section 903 Automatic Sprinkler Systems
903.3 Installation Requirements
903.3.1.2.3 Attics

1. Attic protection shall be provided as follows:

2. Attics that are used or intended for living purposes or storage shall be protected by an automatic sprinkler system.

3. Where fuel-fired equipment is installed in an unsprinklered attic, not fewer than one quick-response intermediate temperature sprinkler shall be installed above the equipment.
Where located in a building of Type III, Type IV or Type V construction designed in accordance with Section 510.2 or 510.4, attics not required by Item 1 to have sprinklers shall comply with one of the following if the roof assembly is located more than 55 feet (16 764 mm) above the lowest level of fire department vehicle access needed to meet the provisions in Section 503.
3.1 Provide automatic sprinkler system protection.
3.2 Construct the attic using noncombustible materials.
3.3 Construct the attic using fire-retardant-treated wood complying with Section 2303.2.
3.4 Fill the attic with noncombustible insulation.
The height of the roof assembly shall be determined by measuring the distance from the lowest required fire vehicle access road surface adjacent to the building to the eave of the highest pitched roof, the intersection of the highest roof to the exterior wall, or the top of the highest parapet, whichever yields the greatest distance. For the purpose of this measurement, required fire vehicle access roads shall include only those roads that are necessary for compliance with Section 503 of the International Fire Code:

4. Group R-4, Condition 2 occupancy attics not required by Item 1 to have sprinklers shall comply with one of the following:
4.1 Provide automatic sprinkler system protection.
4.2 Provide a heat detection system throughout the attic that is arranged to activate the building fire alarm system.
4.3 Construct the attic using noncombustible materials.
4.4 Construct the attic using fire-retardant-treated wood complying with Section 2303.2.
4.5 Fill the attic with noncombustible insulation.

"Noncombustible insulation" is addressed in 3.4 & 4.5.

Alex

8/24/2022 09:52:16 am

Hi,

Is there a desire to go with combustible insulation or can you go with non-combustible? Cost?

NFPA 13 (2019) 9.2.1.13 states spaces having exposed combustible insulation where the heat content of the facing and substrate of the insulation material does not exceed 1000 Btu/ft³, sprinkler protection is not required. To be safe, you should provide protection when using combustible insulation.

Alex

Franck

8/24/2022 11:09:16 am

If it is combustible insulation, you need sprinkler protection.
Or possibly, you can cover it with an non-combustible layer.

All exposed insulation should be removed or covered with a suitable thermal barrier. The following are acceptable:
a. A 1/2" thick coating of Portland cement plaster on metal lath secured to the building structure;
b. A 1/2" gypsum wallboard secured through the insulation to the building structure;
c. An approved proprietary thermal barrier that has a minimum 15 minute fire resistance rating when installed over the specific foam insulation provided.

You can find some guidance with FM Global data sheet 1.57 - Plastic in construction.

Note that the minimum design density, for exposed combustible insulation, should be a minimum of 0.2 gpm/sq ft over 2000 sq ft with 286°F rated K5.6 spray sprinkler heads (for occupancies requiring a lesser water demand or not normally requiring a sprinkler protection), below the combustible insulation.
For a protection above, it depends on the feasibility. If the combustible insulation is attached to the roof, there is no way to protect above it.

Note that if the material is Expanded Polystyrene (EPS), the density can be 0.38 to 0.45 gpm/sq ft depending on its density.

Much better to provide noncombustible insulation!

Michele Rivarola link

8/25/2022 02:05:32 am

The problem with combustible insulation is that it can sag before sprinklers activate and affect the water spray pattern, in extreme cases it can even wrap around the sprinkler. As everyone has recommended replace with a certified incombustible product

Does Combustible Insulation Trigger Sprinklers?

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