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DOW Great Stuff ‘Fireblock’ – Watch Out!

bvillebound | Posted in Construction Techniques on May 19, 2014 06:53am

DOW Great Stuff ‘Fireblock’ Will Catch Fire Before Your Studs!

I was recently working on a major remodel for a home along the shore in Massachusetts, down to the studs in every room.  With all of the changes, this required bringing everything up to current code.  (A key requirement to note if you haven’t run into this before!)  Our inspector wanted new fireblocking / firestopping to meet 2013 standards, for example.  

When I checked the latest version of the IRC and DOW’s info for Great Stuff Fireblock, I ran into a bunch of contradictions and issues.  Here are the key points to remember:

(1) Dow Great Stuff ‘Fireblock’ cured foam will ignite at 240 degrees F  
Wood studs typically ignite at ~350 degrees F, so Great Stuff will catch fire first.  Does this sound like a good material to resist the spread of fire?  I was so surprised that I checked the DOW MSDS (material safety data sheet) — and found that the ignition temperature of cured foam is not mentioned in the DOW MSDS from 2009 to 2013.  I did find a warning on the DOW “consumer safety” document, so I contacted DOW for clarification.  Here is their reply:  “The max-use temperature of the product is 240 degrees F as you stated.”  Copies of DOW’s latest MSDS and ‘consumer safety’ documents are attached.  Note: the same concerns apply to foam ‘fireblock’ products from other manufacturers, e.g. DAP® Fireblock Foam Polyurethane Foam Sealant.

(2)  Check first with your state and inspector!
Fireblock products must be tested according to ASTM E814 (UL 1479). The manufacturers of most poly foam products (like DOW Great Stuff Fireblock) test with a modified version of ASTM E814.  As a result, these products may only be used as an alternate firestop material after a careful review of test reports and with the approval of the local building inspector.  Some state building reg agencies have also taken a closer look and ruled against poly foam “fireblock” products, e.g. the State of Indiana in 2010.  (A copy of the Indiana review is attached.)  So… check with your state and inspector, and make sure he/she will approve foam fireblocking.

(3) ‘Fireblock’ vs ‘Firestop’ — not the same thing
These words sound similar, but they have different meanings in the IRC and state building codes.  There are many details, and here are two good reviews.  To make sure you pass inspection and avoid costly rework, read these guides and your state building regs carefully!

>  North Carolina: www.ncdoi.com/OSFM/Engineering_and_Codes/Documents/whitepaper/Fireblocking%20vs%20Firestopping_.pdf

> Journal of Light Construction:
www.jlconline.com/codes-and-standards/fire-blocking-basics.aspx

(4) Avoid these issues with non-combustible firestop products
After days researching the questions and issues around foam fireblock products, I finally decided: why bother?  There are a number of standard non-combustible products sold by Home Depot, Lowes and most hardware / building supply stores.  For example:   3M® FB 136 Fire Block Sealant and DAP® FIRE STOP Fire-Rated Silicone Sealant.   There is a caveat, of course:  these products are applied with a caulk gun, like shower / window caulk.  This is not as easy as foam, which quickly fills a hole.  This is undoubtedly why foam ‘firestop’ products are so popular.

For me, I will never use a foam ‘firestop’ product again — no matter how easy and cheap it appears.

In case anyone is wondering, I have no connection to DOW or any of their competitors, except as a retail customers.  I simply hope that this info helps you avoid the questions I encountered.

Please see the attached documents for more info.

Mark Hays 

 

 

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Replies

  1. gfretwell | May 19, 2014 09:11pm | #1

    You point out the difference and they have different functions.

    I have even heard suggestions that "fire block" should be changed to "smoke block".

  2. calvin | May 20, 2014 08:42am | #2

    user

    You present some good information, thanks.

    With most foam products needing to be covered with a non com material (or one that doesn't promote flame spread) b/4 passing inspection, I guess that some would walk right on by, not considering that fire"block" product.

    Still, most would look at the label heading and not even skim over the directions or specs.

    On this board, foam is often recommended as an air sealant for penetrations into the attic space.  While this will cut down air infiltration and in many cases would be "covered" on the living side w/drywall or plaster-it still could fail and lead to flame spread from within a wall cavity and into the attic.

    If time for burn through is taken into account-I'd suppose (and could be wrong) that inspection might very well pass a foam fire "block" in these situations.

  3. renosteinke | May 21, 2014 06:44pm | #3

    OP Misleads

    I accuse the OP of misleading with his post.

    There is no requirement that a 'fire block' be fire resistant at all. Nor is there any reason to expect that a 'fire proof' one is better. Let me explain why ...

    "Fire blocking" is simply a method of blocking drafts within building components. There is no expectation that any part of the building be particularlt fire resistant. In this regard, nearly every product we use to stop drafts and patch gaps in insulation burn like rocket fuel.

    The OP implies, with his context and ommissions, that the use of a 'modified' E-84 test is somehow improper. This ignores both the scope and the limitations of the test.

    The test knows as "E-84" was designed to provide a means of evaluating the SURFACE flammability of a product. The way the test is conducted assumes that the material being tested will remain in position during the test. For most materials, this works fine.

    Unfortunately, some materials don't stay together for the test. Insulating fomes, and some plastics, are particularly bad in this respect. At temperatures far lower than their ignition point, these materials fall apart, out of the test area. While these fallen bits often burn with great vigor, they are no longer in contact with the sample, so they cannot continure to ignite the sample. Thus, a highly flammable material can appear to be quite fire resistant.

    To address these details, various modifications to the test have been tried - all in an attempt to  get some usable data.

    "E-84" testing has NOTHING to do with how fire resistant a wall might be. Fire resistance is determined by an entirely different test, one that tests the materials as installed, as part of a wall assembly.

    For example, 1/4" steel plate would -quite properly- test as 'almost zero flame spread' in the E-84 test, yet completely fail any test that applied a fire to one side and measured the temperatures on the "protected" side.

    Foam products are popular as sealants in that they do a fine job of getting into every tiny crevice, and are extremely easy to use. They also tend to be rot proof, do not attract vermin, do not dry out, resist water, are somewhat mold / mildew resistant, and stay in place.

    1. User avater
      bvillebound | Jun 17, 2014 10:44pm | #4

      Facts are facts -- not misleading

      Thanks for your reply.  Here are a few thoughts and comments:

      "Fire blocking" obviously does not need to be non-flammable, as anyone familiar with the Code knows.  Solid fireblocking can be built with standard 2x lumber or OSB, for example.  The concern I have is the degree of flammability and fire resistance.  DOW Great Stuff 'Fireblock' ignites at 240 degress F, a much lower temperature than the ignition point for wood.  In other words, Great Stuff would ignite first.  Does this sound like a good "fire block" material?   Evidently not as good as standard non-flammable fire sealant, which is required for commercial buildings.  We switched to non-flammable 3M and DAP fire sealants for all residential work.

       

      "Modified" E-84 testing:   My apologies; there was a typo in my post.  "E-84" should have been "E-814" as noted in the review by Scott Michael Perez, AIA, CSI, CCS, CCCA, LEED AP, NCARB, Building Compliance Officer with the State of Indiana.  This document was attached to my post; please see page 2 and 3.  Mr. Perez notes:  "What is observed in this report is that all information regarding testing for this product is reduced to only consider the information on the ASTM E 814 test, as there is no mention of the product being tested to conform to either the ASTM E 119 or ASTM E 136 tests.  It was also noted that the same report further documented the fact the ASTM E 814 testing was modified, as noted under Sections 3.1 and 6.3."  Mr. Perez also found that this "modified" test used cement board instead of standard framing lumber (!!).

      Acceptance depends on your state or inspector:  This flammable foam is not listed as an approved fireblocking material in the 2012 IRC, which most state building codes are based on.  Your state or inspector will determine whether it is acceptable as fireblocking in residential construction.  As noted above, we don't need to worry about this;  I switched to standard non-flammable fire sealants.  For me, this simply makes sense.

      I hope this is helpful.

      Mark     

    2. User avater
      bvillebound | Jan 11, 2015 03:46pm | #5

      Flammable poly foam -- IRC rules and ICC certification issues

      First, my thanks to FHB for providing this helpful forum -- a valuable source of information for people in the trade and homeowners.

      In addition to "firestop" and "fire block" labels on these flammable foam products, there are two key issues: 

      IRC rules are lax for residential single family construction:  The IRC does not permit flammable poly foam in a fire block or fire stop assembly for commercial and multi-family construction.  With single family homes, IRC rules are lax.  Basically, the decision to approve/reject poly foam is up to your local inspector.  If he doesn't know better and says 'fireblock foam'  is OK, it is "approved".

      A growing number of inspectors are becoming aware of the flammability issue, however.  As noted above, always check first.  If he fails your inspection, you will spend costly hours digging the foam out of penetrations, then refilling the holes with non-flammable caulk.  

      If you are a homeowner or responsible residential contractor / builder, this highlights the need to be better informed.  

       

      The product certification process is a key issue with flammable 'firestop' foam products.  If you review the technical documentation, you will find that all of these products were "approved" by the ICC.  If you dig further, you will find that the ICC never tested these products -- they relied on test reports provided by the manufacturers, e.g. for a "modified version of ASTM 814".  Note the key word, "modified".  (A copy of the ICC report for Great Stuff is attached for your review.) 

      Like me, you may wonder, "What does 'modified' mean?  What test did the manufacturer actually perform?" You will find that the test reports manufacturers provide to the ICC are not available.  In short, the value of ICC "certification" is minimal products like these.  

      The reason canned foam 'fire block' products are popular is ease of application.  Canned foam is easier to apply than non-flammable caulk.  Foam quickly fills holes and no backing is required.  'Quick and easy' often trumps 'effective' with some contractors.

       

      We will never use flammable poly foam for 'fire stopping' again.  Non-flammable caulk is readily available from Home Depot, Lowes and trade distributors.    

       

      I hope this is helpful.

       

      Mark 

      File format
  4. BldgSuppRetailer | Aug 04, 2016 05:50pm | #6

    BOSS 813 Expanding Firestop Foam

    This is the only PU Foam product that I've been able to find that qualifies as a 'FIRESTOP'. It passes E814 Standard test method and meets all codes nationally for commercial construction for 1 and 2 hour systems.

    NO, I do not work for BOSS. I'm a retailer and I've been dealing with this fireblock issue for years. I've had so many customers wanting to use the much cheaper fireblock when they need firestop that I stopped carrying the fireblock altogether.

  5. severaltypesofnerd | Jun 19, 2023 03:58pm | #7

    And for those tempted to use "Fireblock" foam around gaps in fire sprinklers, there's cold water to be thrown on your head from the biggest maker of CPVC sprinkler pipe:

    General-Purpose Gap Filling:
    For general-purpose filling of small gaps around FlowGuard Gold, BlazeMaster, or Corzan pipes in wall or floor penetrations (not fire-rated constructions), either RTV silicone sealant or polyurethane "foam-in-a-can" may be used. Other types of general purpose sealants may or may not be compatible. Always check with the product's manufacturer for recommendations. See also Lubrizol's list of caulks and sealants known to be incompatible.

    But the "Fireblock" foams have extra chemical additives that may or may not be CPVC compatible, and thus unsuitable for fire rated penetrations (which will be most of them).

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