Spray Foam in Exterior Fire-Rated Wall Assemblies

[ACDC]

Project is new construction R-2, 3-unit building, Type VB, sprinklered, reviewed under IBC 2018

2 of the project's exterior walls are between 5-10' fire separation distance and required to have 1-hr rating per Table 601. We want to use spray foam insulation in our wall cavity, but I am not finding any UL tested, rated exterior wall assemblies with spray foam insulation. Our jurisdiction is always asking for UL design numbers on our assemblies. In the past we have used UL-V311 assembly for the 1-hr rating from both sides, but this assembly only calls out batts or blankets for the insulation component.

Has anybody else found a method for specifying a 1-hr rated exterior wall with spray foam?

I'm looking at section 2603.5 for use of foam plastics in exterior walls. This seems to say that buildings of type VA or VB are exempt from section 2603.5.1 that requires "data based on tests conducted in accordance with ASTM E119 or UL 263" for rated wall assemblies in any other construction type. If this is the case, should I be using section 721 for prescriptive fire resistance to determine the exterior wall rating? And then would we only be subject to the requirement that the foam is covered by a thermal barrier per 2603.4?

 

[RLGA]

I just checked UL Product iQ, and it does have fire-rated assemblies with "Foamed Plastic, Insulation" (look under "Additional Filter), which includes sprayed polyurethane foam (SPF) insulation. I have noticed manufacturers listed in the assemblies that include NCFI Polyurethanes, Carlisle Spray Foam Insulation, and BASF Corp.

Both UL and the Gypsum Association (GA) mention that mineral fiber (glass or wool) insulation can be added to any assembly. GA-600 also includes cellulose fiber insulation in the list of permitted insulations. Neither mentions SPF.

Type V buildings must still have fire-rated exterior walls per Tables 601 and 602 that are tested per ASTM E119 or UL 263. Section 2603.5 only restates this so that the general-versus-specific provision of Section 102.1 does not change the intent for fire rating of exterior walls. Without restating the fire rating provision, Section 2603.5 could be considered a more specific fire performance requirement than the more general exterior wall fire rating requirements of Chapters 6 and 7.

The prescriptive assemblies within the tables of Section 721 will mention insulation if insulation is permitted. The calculated method of Section 722 does not mention SPF insulation in Table 722.6.2(5). However, that does not necessarily mean you cannot use SPF insulation in fire-rated walls determined by the calculated method. My suggestion is to use the calculated method per Section 722 without adding time for the insulation and provide a thermal barrier as required by Section 2603.4.

 

[ACDC]

Wow, thank you Ron!

I think you're exactly right here. I wasn't able to find a perfect match for our walls in UL Product IQ (But that was very helpful). However, I should be able to get there by using Section 722.

 

[KHL]

I realize it's been a few months...but I am currently looking into this same question - a rated assembly for exterior walls with spray foam insulation.
I did find UL #W307 - which fits my situation - with type VB.
The only downside is that we were planning on osb sheathing, vs gypsum sheathing. But it does include a variety of exterior siding options, from brick to vinyl.

 

[RLGA]

Is the fire exposure from the interior side only (i.e., fire separation distance is greater than 10 feet) or from both sides (i.e., fire separation distance is 10 feet or less)?

If the former, then look at Design No. U391. There is no concern about the type of exterior wall covering material used on the exterior side since exterior exposure is not considered. Exterior wall coverings need only comply with Chapter 14 in this situation.

 

[KHL]

Is the fire exposure from the interior side only (i.e., fire separation distance is greater than 10 feet) or from both sides (i.e., fire separation distance is 10 feet or less)?

If the former, then look at Design No. U391. There is no concern about the type of exterior wall covering material used on the exterior side since exterior exposure is not considered. Exterior wall coverings need only comply with Chapter 14 in this situation.

Good question - specifically the enclosed exit access stairs, which require the exterior rated walls, and expanding 10ft horizontally on adjacent walls at less than 180 deg from stair wall. The remainder of our exterior walls are not required to be rated as we are 60+ feet from any other structure in all directions.
So I believe the intent would be fire exposure from the interior, is that right? Sorry, I need to learn more about interior vs exterior exposures.

 

[RLGA]

Good question - specifically the enclosed exit access stairs, which require the exterior rated walls, and expanding 10ft horizontally on adjacent walls at less than 180 deg from stair wall. The remainder of our exterior walls are not required to be rated as we are 60+ feet from any other structure in all directions.
So I believe the intent would be fire exposure from the interior, is that right? Sorry, I need to learn more about interior vs exterior exposures.

Are you sure you are referring to exit access stairs and not exit stairs?

Exterior walls of exit and exit access stairs do not need to be rated unless the fire separation distance requires it per IBC Table 602. For exit stairs, if the exterior wall is rated as required for the interior walls, then the adjacent exterior walls less than 180 degrees from the stairs are not required to be rated for the 10-foot distance.

Exit access stairs are only required to comply with the requirements for shafts and not the requirements for exit stairs, including the exit stair requirements for adjacent exterior walls less than 180 degrees from the exit stair when the exterior wall is not rated.

 

[KHL]

Are you sure you are referring to exit access stairs and not exit stairs?

Exterior walls of exit and exit access stairs do not need to be rated unless the fire separation distance requires it per IBC Table 602. For exit stairs, if the exterior wall is rated as required for the interior walls, then the adjacent exterior walls less than 180 degrees from the stairs are not required to be rated for the 10-foot distance.

Exit access stairs are only required to comply with the requirements for shafts and not the requirements for exit stairs, including the exit stair requirements for adjacent exterior walls less than 180 degrees from the exit stair when the exterior wall is not rated.

You just hit on something that I can't believe (or maybe I can) I've muddied up. They are exit access stairs - basically an extension of the corridor to the exit on the first level - allowable based on not exceeding the exit access travel distance. So therefore not required to be a shaft enclosure, so no exterior wall rating req'd.
THANK YOU!

 

[Paul Sweet]

Don't forget to look at IBC 2603 Foam Plastic Insulation. 2603.5.5 requires NFPA 285 compliance if you don't meet the exceptions.

 

[RLGA]

You just hit on something that I can't believe (or maybe I can) I've muddied up. They are exit access stairs - basically an extension of the corridor to the exit on the first level - allowable based on not exceeding the exit access travel distance. So therefore not required to be a shaft enclosure, so no exterior wall rating req'd.
THANK YOU!

"Extension of the corridor" -- Do you mean this is an exit passageway that has some steps along the route because of a grade change?

Don't forget to look at IBC 2603 Foam Plastic Insulation. 2603.5.5 requires NFPA 285 compliance if you don't meet the exceptions.

Not for Type V construction per Section 2603.5.

 

[KHL]

"Extension of the corridor" -- Do you mean this is an exit passageway that has some steps along the route because of a grade change?


Not for Type V construction per Section 2603.5.

 

[KHL]

"Extension of the corridor" -- Do you mean this is an exit passageway that has some steps along the route because of a grade change?


Not for Type V construction per Section 2603.5.

The stairs would be interior exit access stairs. I believe, that because it if fully sprinkled (1019.3, ex 4), and because it is only two stories (1019.3 ex 1) the exit access stair is not required to be enclosed with a shaft enclosure. Although they are enclosed, not actually open to each story.
2 story R2, VB, fully sprinkled.
2nd level - One central corridor with interior stairs at each end of the corridor - stairs exit to the exterior one level one.
First level - One central corridor to exits directly to the exterior.

When I read 1023.7, I interchanged exit stair for exit access stair, which sent me looking for exterior wall assemblies

 

[RLGA]

The stairs would be interior exit access stairs. I believe, that because it if fully sprinkled (1019.3, ex 4), and because it is only two stories (1019.3 ex 1) the exit access stair is not required to be enclosed with a shaft enclosure. Although they are enclosed, not actually open to each story.
2 story R2, VB, fully sprinkled.
2nd level - One central corridor with interior stairs at each end of the corridor - stairs exit to the exterior one level one.
First level - One central corridor to exits directly to the exterior.

When I read 1023.7, I interchanged exit stair for exit access stair, which sent me looking for exterior wall assemblies

Okay, now I understand. If the travel distance can include the distance down the stairs without exceeding the maximum distance, then the stairs can be exit access stairs.