072500 and 074264 Air Barriers/MCM Panels and NFPA 285 test

Archive of Older Topics Archive - Specifications Discussions #5
1

This forum has discussed NFPA 285 requirements for plastic insulation and an article from the ICC website clearly mentions that the assembly as a whole be tested - not something similar. see this link for the previously discussion http://discus.4specs.com/discus/messages/24/5477.html

Now a new wrinkle as sprung up. It appears that air barriers are considered a portion of the assembly as is the insulation, gypsum sheathing and in my case MCM panels.

HOW oh HOW are we building buildings without a constant stream of assemblies being trotted off to testing labs for the 30K NFPA 285 test for your PARTICULAR assembly?

This question came up last week on a job. The MCM manufacturer stated that they felt our vapor impermeable membrane would contribute to a failure in the system when tested and were anxious about its choice. They stated that they knew of several Vapor Permeable products on the other hand that would be OK.

I was at a loss. The NFPA 285 requirement has been in the IBC since 2000.

Why had this never come up before?

Have project architects been receiving these test results? They have been required in all of my specs since 2008(ish) (Thank you Speclink you have included this as standard language) Masterspec does NOT reference this test only ASTM E 84 and E 119

What is the difference, in a fire, between vapor permeable and impermeable?

How are air barriers or other products tested separately from the whole assembly?

Will the contractor/manufacturer have to test (at a cost of $30,000 each time) the MCM exterior wall assembly every time a different air barrier or insulation is selected?

There are 15 to 20 different MCM systems, tens of air barriers, hundreds of insulation brand names and products, resulting in thousands of possible combinations!

I got out NFPA 285 and read thru it. The test standard states in section 5.7 that

The test specimen shall be constructed and secured using fastening and construction details representative of actual field installation as specified by the manufacturerjoints or seams representative of standard construction practicesshall be incorporated

I called NFPA and ask them what they thought. They agreed with me that testing every possible combination was never the intent of the standard but that the system does have to be tested.

The exterior assembly consists of the metal studs, the gypsum sheathing, the air barrier, any accessory tapes and sealants, the outboard insulation, the MCM framing system, the MCM panels. The sheathing, air barrier, and insulation are parts of the assembly (not joints and seals) that would logically need to be tested. The sheathing for our buildings is always Type X Gypsum sheathing has been part of these tests historically and should not be an issue.

Exterior insulation and the air barrier are two additional elements in the assembly that can affect test results.

I called my local Carlisle rep (their impermeable product is scheduled for the building at this time) He stated that he had just heard of this issue and the company had developed a new impermeable product that would be OK in the test assembly. Their new product literature states that the product complies with NFPA 285 what does that mean? He is getting the test or engineering reports for me at this time to clarify this.
I called the rep for WR Grace and he had not heard of this issue either but with a little digging found a letter that stated that Grace perm-a-barrier and XPS insulation (Extruded Polystyrene) should be fine when testing assemblies per NFPA 285. Again what assemblies were tested?

The Local reps for MCM panels were similarly in the dark and both are investigating.

Im still investigating and Im now broadening my reach.

WHAT are you folks doing?.

Here are the choices I have at the moment:

  1. Stop using MCM panels
  2. Specify only those air barriers approved by the MCM manufacturer (with test results required, of course)
  3. Specify air barriers that will not generate flame or elevate the wall temperature beyond those listed in NFPA 285. Then make assumptions about possible test results and place the burden of testing upon the MCM fabricator (and add 30,000 dollars to your project cost.)
  4. Make the Contractor submit similar tested systems to the Authority Having Jurisdiction AHJ for the hope of approval without new testing.
2

Marc, take a look at what is coming in the 2012 IBC:

1403.5 Vertical and lateral flame propagation.
Exterior walls on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain a combustible water-resistive barrier shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.

3

I remember a plan reviewer for California OSHPD way back in 1993 or so asking my firm to provide the edge of slab UL fire-safing assembly we intended to use for a high-rise hospital in LA.

Looking in the UL assembly book at that time, one found as I recall, 3 assemblies or so for things like brick veneer on a steel frame and metal deck high rise, and something with CMU and a veneer and one or two hyper specific wall assemblies where half the listed products were already out of production.

This was California, so that job, and many others, were put on hold until our various clients with their architects and clients, provided tests, or engineering judgements so the various projects could move forward.

4

Alan, interesting that it states “combustible water-resistive barrier”.

Marc, this may be why you received the comment about vapor permeable vs. vapor impermeable though I’ve heard it more as sheet vs. fluid-applied. My understanding is that foam insulation plus asphaltic sheet membranes equal too many sources for combustion. What product is Carlisle suggesting?

5

The 2012 IBC throws NFPA 285 into many other materials in chapter 14. They now include HPL to have the test. The MCM requirement has been in chapter 14 of the IBC since 2003. Prior to that they only had ACM and it did not reference NFPA 285 at all. That means that the testing requirement has been in existance for almost 10 years.

Ken, can you name me one “water-resistive barrier” that is not combustible? Will this new requirement throw all wall systems into the requirement to be a tested assembly? Will exterior wall systems need to be required to have an assembly test similar to UL tested assemblies?

6

the new carlisle costing is Barritech - NP for non-permeable vs their existing Barritech which is vapor permeable.

7

Marc, This is a big problem as you can see. It also applies to any wall assembly using foam insulation in the cavity, which could include brick veneer. The Boston chapter of the Building Enclosure Council (a committee of the Boston Society of Architects) has been looking at this for some time. We’ve done some research, such as finding out that there does not appear to be any fire loss history as a result of these constructions. The Boston BEC in conjunction with BETEC has raised significant funds to sponsor research into this issue, and ultimately to propose a change to the ICC to address this problem. Unfortunatley, under the best scenario that is 3 years away.

As far as the air barriers are concerned, the basic problem is that they could contribute fuel to a fire. Some research I had done a couple years ago suggested that this was especially true if the membrane was asphalt-based, but I don’t know if the non-asphaltic products truly contribute less fuel. Our problem was that only the asphalt products (at least at that time) were impermeable.

I think the reason no one paid any attention to this was that it kind of snuck up on us all. Massachusetts has been building walls like this for a long time now, and when we finally adopted the IBC it put a monkey wrench into everything.

My personal opinion is that this provision of the code is a solution looking for a problem when it comes to MCM and cavity wall systems.

8

This is something I have come across ocassionally. I’ve been informed that ICC is looking into the issue due to the cost of testing, the emphasis in the IECC for continuous insulation on exterior walls, and the superior performance of foam insulations over other types such as mineral wool.

I’ve had some success getting approval using foam based products that, by themselves, pass NFPA 285, and the application of materials over the insulation system, such as masonry, stone, or other noncombustible exterior wall coverings, does not alter the performance of the base insulation system. I’ve specified products like Centria’s MetalWrap and similar products. These provide both an insulated layer and a water-resistive barrier.

I think what will occur is that through ICC’s code development process the IBC will eventually incorporate prescriptive requirements that do not require the NFPA 285 test. This may take some initiative on the part of insulation manufacturers. There may also be a push to create tested UL assemblies and incorporate them into UL’s fire-resistance directory.

Until then, we’ll have to live with what the IBC provides, come up with alternative methods and materials, get the code to change, or persuade local jurisdications to create amendments that makes this requirement less restrictive.

9

ICC has a good white paper on this subject available online for all to read:

http://bsj.iccsafe.org/august/features/code_and_fire.html

The excerpts that I think most of us will be very interested in are:

“Even though a specific component of the wall system has met the requirements of NFPA 285, if additional combustible components are added to the wall assembly, then the assembly may no longer meet NFPA 285. For example, if a Metal Composite Material (MCM) by itself is successfully tested via NFPA 285, and if a CI such as foam plastic is added to the system, the new combination of materials may not meet the Code and the NFPA 285 performance requirements. The new combination wall assembly must be tested.”

“In summary, with the increased use of CI, the NFPA 285 is an important test to evaluate and control the fire performance of foam plastic used in CI exterior walls such as that shown in the above illustration. The test applies to most exterior walls that contain foam plastic insulation in Types I, II, III and IV construction. The results of the test are limited to the assembly tested and if you change wall components or add new combustible materials, additional NFPA 285 testing may be required to verify that the wall assembly meets Code.”

Not a lot of wiggle room in this language, and Marc’s question is still valid: How are all of these exterior wall systems getting by the code officials when they have clearly not all been tested as specific assemblies in accordance with NFPA 285?

10

In the diagram included in that link, the horizontal “Structural Zee Spacer” is continuous and probably constitutes a thermal bridge that would negate the continuous insulating properties of the assembly.

Alan, I don’t know of any membranes not considered as addtional fuel to the fire.

The feedback we got from one XPS manufacturer was that their product could be used over most fluid-applied products but there were issues about self-adhering sheet (aka rubberized asphalt sheets). I requested but never saw NFPA 285 testing.

I keep hearing that testing has been done on this product or that, but I’m starting to feel like I’m on a snark hunt when trying to find a tested assembly.

11

“How are all of these exterior wall systems getting by the code officials when they have clearly not all been tested as specific assemblies in accordance with NFPA 285?”

In my opinion, the answer may lie in the fact that some building departments are not reviewing these items. If they are only accepting the drawings and not any specs, then how do they know that what is in the drawings meet the code required testing? Building departments seem to be mainly looking at life safety issues like type of construction, exiting, occupant load, exit travel, accessibility (if part of the adopted code), etc. They seem to be concentrating mainly on Chapter 4 - Chapter 11.

However, another question comes to mind if we were doing a little soul searching. How did we not discover this earlier? Who is at a bigger risk? The building official is not going to be at risk. The architect is going to be at risk.

12

Given the code adoption cycle the 2018 IBC is the soonest you will get that in the code. In California this will mean that the provisions does not become mandatory before Jan of 2020.

I believe that if we enforced the code strictly we could stop at least 90% of the construction

13

I don’t think WE need to so any “soul-searching”. This is another example of code-writing bodies with the best of intentions putting something in the code that doesn’t make sense (in most cases). We know that plastic insulation burns. We know we need to protect life safety. What is the best way to protect people’s lives if there were to be a fire? The testing that is currently being done will help us understand where the weak points really are. It may also show us if we need to be concerned about certain parts of building enclosure and how to detail it properly.

A somewhat similar parallel occurs in the masonry industry. Everyone knows that brick and block don’t burn, but designers are always asking us (BIA) for UL numbers that they can refer to. The industry has not done any wideranging fire testing since the 1940s and 50s when much of the research was conducted. At that time, and since with actual performance, there wasn’t a need to test every assembly because all masonry resisted fire in much the same way. So we don’t use UL (and other) numbers for fire resistance, we use calculated fire resistance. This has been accepted by the codes and building code officials. This saves the industry from the expense of testing every permutation that designers come up with. The testing laboratories don’t like that very much since they aren’t being paid to run all of these tests. So in some cases there could be some common features of walls where we wouldn’t have to test every assembly. Making one assumption may be enough for a whole range of products or assemblies. The problem is the codes haven’t caught up or been asked to come up with a solution.

I think Mark is right, 90% of construction could be affected by this somewhat innocuous ruling. For myself, I have NEVER heard of a brick wall with rigid insulation in the cavity contributing to a fire. I await word of someone who has.

14

My local Carlisle waterproofing rep just sent me a copy of a letter sent from Hughes Associates, Inc. to the Extruded Polystyrene Foam Association. Entitled Analysis and Extension of NFPA 285 tests HAI Project No.: 1JJB00060.001 They have summarized tests from several locations and made additional small scale tests on various “weather resistive barriers” . The engineer then goes on to issue his judgment that:

Based on the results of these tests, additional small-scale tests of the weather-resistive barriers and my experience with the NFPA 285 fire test, it is my judgment that the various configurations of exterior walls described in Table II will meet the performance requirements of NFPA 285.

This is the best I can hope for at this time without having EVERY exterior assembly (in Types I II III IV buildings) containing combustible materials tested when used with an air barrier (as if I have ANY wall assembly with out an air barrier.

I have alerted the architects in our offices to be aware of this issue. My Building Insulation section (as the CI is found there) will reference the requirement for the NFPA 285 testing. My Air Barrier section will also require it. We will offer up this letter and other similar notes to code officials as we can. HOWEVER, the onus will be on the manufacturer/contractor to cough up 30K for a test or convince the AHJ that things are OK The upshot is that I will probably do two things, move to mineral fiber insulation where I can and use air barrier products that have as much proof of non-combustibility as possible.

Remember this issue came to me from the air barrier side NOT the insulation side. If I have an air barrier material that is NOT a plastic and NOT combustible then I do NOT have to test the wall because Im NOT in chapter 26!

PS

I agree with what Brian stated above. The ICC references tests right and left without (it seems) understanding of the wide ranging effects that reference can have. The test is just a test.

Additional information
http://www.centriaperformance.com/pdfs/Beitel%20Spiewak%20Fire%20Code.pdf
http://www.foamsheathing.org/images/TM_NFPA_285_Assemblies.pdf
http://www.icc-es.org/Criteria_Development/1102-pre/Memos/13_AC12_Memo.pdf

I hope that helps everyone. I dont know how to post the full letter that I received. But here is the table of air barriers.

Weather-resistive Barrier applied to Gyp Sheathing

Green GuardMax Building Wrap - Pactiv
WeatherMate or WeatherMatePlus Dow Chemical
Tyvek CommercialWrap - Dupont
Backstop NT Dryvit
Barritech VP Carlisle
AIR-SHIELD LMP (Black only) - W. R. Meadows
Perm-A-Barrier VPS - W.R. Grace

Weather-resistive Barrier applied to Foam insulation

Green GuardMax Building Wrap Pactiv
WeatherMate or WeatherMatePlus Dow Chemical
Tyvek CommercialWrap - Dupont

15

anyone that wants the letter can get it here:

http://www.icc-es.org/Criteria_Development/1102-pre/Responses2/13_AC12.pdf

16

apologies, not the letter Marc references, I hit the button prematurely, but the link I provided does offer some additional information to those interested.

17

similar but not the same letter. the one I got had a table of potential assemblies and the “tested” air barriers

18

I have been thinking about this issue and tend to agree with Brian about whether or not this is a “real” issue or a code issue that is based on a percieved issue. Most code implementations and revisions are reactionary; they are responding to failures of some sort. While model building codes probably should be a bit more proactive, this particular one seems to be somewhat speculative and even specious. I am simply not sure of the context from which these issues arise.

I do see problems with EIFS (which is where I suspect this originates, and I am not sure about using this in metal wall panel assemblies, but I simply fail to see how plastic foam insulation and air barrier products can be a problem when incorporated into exterior wall assemblies with masonry veneer, cement plaster finish, or stone/ceramic veneers adhered to substrates. This assumes that there is a layer of gypsum sheathing and interior gypsum wallboard (or similar stuff) between these products and the building interior.

Ron… Can you shed some light on this?

19

There was a resent fire in China where a rigid insulation was being installed on the exterior of the building and the building caught fire during construction and was quickly engulfed in flames. I do not know if this had any influence on the change but it was a dramatic fire.

20

nope
this has been in the code for quite a while - it’s just the addition of the Air barriers that made it pop to the foreground and THEN you start reading NFPA 285 and go nuts.