2603.5 Exterior walls of buildings of any height.

[Fritz]

The building is a multi-story Type I-A, fully sprinklered construction.

The exterior wall does not require any fire resistance rating, more than 30’ open yard.

The makeup of the exterior was is exterior brick veneer, 12” block, sprayed on foam insulation, metal stud with an interior sheetrock finish.

I have been going in circles trying to decide if the foam insulation is part of the so called non-combustible wall, or something else. The foam meets the testing requirements of chapter 26, and has the thermal barrier; however my comfort level is just not there. It just seems if a designer wants to make something better, improve insulation, and it meets the flame spread and all that good stuff it should be ok. On the other hand, if you look at 602.3, for Type III construction, just for S&G and thinking equivalencies, exterior walls are also Non-combustible and specifically only allows FR lumber in the wall assembly. It does not benefit from 603. My thinking is that if the foam was an integral part of the assembly, say it was sandwiched in the non-comb assembly, now we have a different issue, but added on to the assembly leave me with some questions. So what am I missing.

 

[texasbo]

I agree with you. Just as if you had wood finish on the sheetrock, there is no violation of the noncombustible requirement for the exterior wall. As long as flame spread, interior finish requirements, and/or foam plastic insulation requirements are met, it is not an issue.

As to your reference to the Type III requirements, what we're talking about here isn't "in" the wall assembly. That same Type III example could certainly have application of non-FR wood finishes.

 

[SBerg]

You need to check the ES-report and verify it has been tested for Type 1 construction.

In most cases the use of sprayfoam is limited to Type V structures.

Alternately the designer can provide a tested fire-rated assembly using the foam.

Where in the code does it allow for a reduction of exterior wall rating in type 1, other than the 1 hour sprinkler allowance?

 

[texasbo]

Where in the code does it allow for a reduction of exterior wall rating in type 1, other than the 1 hour sprinkler allowance?

Although it sounds like they have a 1 hour wall, and not the OP question, table 602, 2006 IBC does not require rating if FSD greater than or equal to 30'.

 

[texasbo]

You need to check the ES-report and verify it has been tested for Type 1 construction.In most cases the use of sprayfoam is limited to Type V structures.

Please note that 2603.5 does not limit it to Type V buildings. Minimum flame spread and smoke developed rating requirements must be met as I've already posted, and a vapor barrier is required. Since this is not a rated wall, compliance with ASTM E-119 not required.

 

[Fritz]

Thanks guys, it is good to hear differing opinions or agreeing opinions based on our combined experiences. The sun is out and it is warm and my VTX needs to be ridden this afternoon.

 

[peach]

I think you're looking in the wrong place. Table 602 with FSD > 30 feet requires 0 fire resistance rating; with Type 1A, it's the structural frame that's important.. not the wall. Section 603 addresses combustible material IN the building; the exterior wall is not in the building. A great question for ICC interpretation though.

We see rigid foam insulation on the exterior building cladding all the time.

 

[Fritz]

The building in question has a structural frame that is protected. So the block wall is kind of a self supporting curtin wall.

I just remember in a project, 15 or 20 years ago, or older. NO smart remarks needed here, yes I had to walk to school, uphill both ways! Where in a 2 or 3 hour bearing wall, type I-A constuction we had a sandwich wall with a rmax insulation sandwiched between the two layers of non-comb, brick and block. The testing in that day only allowed for the rmax and or thermax in the assembly. I do not know if rmax is even available anymore.

 

[Paul Sweet]

You also need to look at IBC 719.

 

[peach]

well, the drywall is the thermal barrier. Not exposed.. not cellulose loose fill. 719 keeps kicking back to 2603, which appears to reference fire rated wall (0) and thermal barrier (interior finish). Having scanned 2603 both code and commentary, it appears to be an irrelevant issue. Even 2603.5.7 addresses fire exposure from the outside.

 

[Francis Vineyard]

The makeup of the exterior was is exterior brick veneer, 12” block, sprayed on foam insulation, metal stud with an interior sheetrock finish.

Peach is correct all you need is the ½ gypsum separating it from the interior; 2306.4. And the block wall separates it from exterior as well; 2306.4.1.1

From this link it appears it met NFPA 285 for all exterior walls; note the application of spray foam within the stud wall.

2603.5.5 the manufacturer of foam plastic insulation can answer technical questions related to specific as assemblies or veneer types not shown here; http://www.rci-online.org/interface/2010-01-hansbro.pdf (forum member?)