Combustible Space Now w/ Polyurethane Foam?

4/27/2020

There is a commercial structure that has been sprayed with an application of polyurethane foam insulation above drop ceilings within a Type II-B constructed building.

Cut sheets for material with liquid-applied intumescent coating would indicate it may comply with the definition of limited combustible material by NFPA 13.

Based on cut sheets for applications the reference is to a Type V construction and the project that it is being utilized in is a Type II-B construction therefore we have required fire sprinkler protection above ceilings.

My question is: would the application of this polyurethane foam insulation constitute a combustible concealed space, required to follow NFPA 13, Section 8.15.1.1?

Section 2603 of the IBC address installation of foam.

3.3.16* Limited-Combustible (Material). Refers to a building construction material not complying with the definition of noncombustible material that, in the form in which it is used, has a potential heat value not exceeding 3500 Btu/lb (8100 kJ/kg), where tested in accordance with NFPA 259, and includes either of the following: (1) materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of 1⁄8 in. (3.2 mm) that has a flame spread index not greater than 50; or (2) materials, in the form and thickness used, having neither a flame spread index greater than 25 nor evidence of continued progressive combustion, and of such composition that surfaces that would be exposed by cutting through the material on any plane would have neither a flame spread index greater than
25 nor evidence of continued progressive combustion, when tested in accordance with ASTM E84, Standard Test Method of Surface Burning Characteristics of Building Materials, or ANSI/UL 723, Standard Test Method of Surface Burning Characteristics of Building Materials

8.15.1.1 Concealed Spaces Requiring Sprinkler Protection. Concealed spaces of exposed combustible construction shall be protected by sprinklers except in concealed spaces where sprinklers are not required to be installed by 8.15.1.2.1 through 8.15.1.2.18 and 8.15.6.

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7 Comments

Jesse

4/27/2020 10:20:42 am

I believe this may create a combustible concealed space requiring protection. The concern is that you indicated the cut sheet stated it "may" meet the definition of limited combustibility. I think the AHJ and most definitely the underwriter would want stronger affirmation. The concern is that as the polyurethane begins to pyrolysize, it not only off-gases combustible gases as a result of the pyrolysis, but also creates a running fuel fire and the resultant vaporization and the secondary ignition from the now flammable / combustible liquid. Without protection is mitigate this, the positive heat feedback allows severe promulgation of the fire.

Just my humble opinion though

James

4/27/2020 10:23:39 am

Is this something that could be field applied and tested in the parking lot with the fire department?

I'd be curious how it reacts and burns compared to actual limited-combustible materials (and also am looking for excuses to get out of the house and see some controlled pyrolysis in person...).

4/27/2020 10:38:37 am

Not unless the FD has a secret UL testing lab in a trailer I'm afraid. Depending on the AHJ, I've known some that would accept that years ago. Undoubtedly, the insurer would not unless it has a UL or FM seal on it.

Today, I can't see any AHJ that doesn't want to be wrapped up in years of litigation accepting it.

4/27/2020 10:58:06 am

Fair enough... I agree... : )

Franck

4/27/2020 10:54:43 am

I can confirm Jesse comment regarding Insurance Companies. They would probably not accept the situation as non combustible. Real testing of a sample in a parking lot is not an accepted method for approval. To be honnest, even an approved testing method is sometimes not sufficient as you test the materials but not the situation where it is installed (vertical panels do not burn the sale way as horizontal panels, for example)

In addition, polyurethane type materials emit toxic gases that could affect manual firefighting operations.

4/27/2020 10:58:10 am

As a former insurance engineer for a very large property carrier, we'd write this as a 100% probable maximum loss scenario unless that area is protected, or unless there's UL / FM data supporting the lack of combustibility.

Brian Gerdwagen FPE

4/30/2020 04:00:18 pm

I think you have a larger problem than sprinklers. Foam needs to be checked in the applicable building code. Usually there is a requirement for a thermal barrier, or at least an ignition barrier between it and the space above.

There is also the question of return air plenums. If the foam is greater than 25 FS and 50 SD, you can not use the product in a return air plenum.

Combustible Space Now w/ Polyurethane Foam?

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