WHITE PAPERUSGStructuralSolutionsUSG STRUCTURAL PANELSEVALUATION OFNONCOMBUSTIBILITY FORCERTAIN STRUCTURALMAGNESIUM OXIDE PANELSINTRODUCTIONIn recent years Magnesium Oxide (MgO) structural panels manufactured outside of the United Stateshave become available for sale as structural subfloor and structural roof deck panels in the United States.Manufacturers of these products may claim that these panels are noncombustible. They are not.For the past 120 years, USG has developed products that meet or exceed standard requirements and takespride in being a leader in the building materials industry. The safety and wellbeing of USG’s customers isimportant, and the public should be aware of the facts behind “noncombustibility” claims being made by thecompanies that manufacture and sell the following MgO structural panels: NOCOM Dragonboard extremegreen (currently known as EXACOR ) MEGABOARD USG has procured these panels in the marketplace and provided them to an independent, thirdparty laboratory. Industry-standard testing conclusively shows that they do not conform to thenoncombustibility requirements of ASTM E136, Standard Test Method for Assessing Combustibility ofMaterials Using a Vertical Tube Furnace at 750 C, as defined in the 2012, 2015 and 2018 IBC model codes.NONCOMBUSTIBILITY IN THE IBC(2012,2015 AND 2018) MODEL CODESThis white paper will clarify where noncombustible construction is required per the InternationalBuilding Code (IBC), how to evaluate for noncombustibility, and the differences betweennoncombustibility, flame spread and fire-resistance.From the International Code Council website:“The International Code Council was established in 1994 with the goal of developing a single set ofnational model construction codes that came to be known as the International Codes, or I-Codes. TheI-Codes are a family of 15 coordinated, modern building safety codes that help ensure the engineeringof safe, sustainable, affordable, and resilient structures (ed: The IBC is an I-Code).The I-Codes are the most widely accepted, comprehensive set of model codes used in the UnitedStates. All 50 states, the District of Columbia, and many other countries have adopted the I-Codes atthe state or jurisdictional level."Section 602.2 of the IBC defines Types I and II construction as follows:Section 602.2 Types I and II. Types I and II construction are those types of construction in whichthe building elements listed in Table 601 are of noncombustible materials, except as permitted inSection 603 and elsewhere in this code.Table 601 includes “floor construction and associated secondary elements,” as well as “roofconstruction and associated secondary members” under the heading “Building Element.”Table 601 - Fire-Resistance Rating Requirements for Building Elements (Hours)Building ElementType IType IIType IIIType IVABABABHTType VABPrimary structural frame (see Section 202)321010HT10Bearing walls: Exterior321022210Interior3210101/HT10Nonbearing walls and partitions: ExteriorSee Table 602Nonbearing walls and partitions: Interior000000SeeSection2304.11.200Floor construction and associated secondary members(see Section 202)221010HT10Roof construction and associated secondary members(see Section 202)1-1/2 11010HT10

NONCOMBUSTIBILITY IN THE IBC(2012,2015 AND 2018) MODEL CODES, CONT.As defined in Chapter 2 of the IBC, “secondary members” are those structural members of thefloor construction and roof construction not having direct connection to the columns. Therefore,structural subfloor and roof deck sheathing are considered “secondary members” which must benoncombustible in Types I and ll construction.The 2012, 2015 and 2018 IBC model codes define noncombustibility in Section 703.5.Section 703.5.1 Elementary Materials. Materials required to be noncombustible shall be tested inaccordance with ASTM E136.Section 703.5 further notes that the term “noncombustibility” does not apply to the flame spreadcharacteristics of interior finish or trim materials. Other fire performance-related tests like the test forflame spread (ASTM E84) and the standard for performing fire tests on building construction systems(ASTM E119) should not be confused with the test standard for noncombustibility (ASTM E136).ASTM E84, also known as the Steiner Tunnel Test, evaluates the surface burning of combustiblematerials and provides a Flame Spread Index (FSI) and Smoke Developed Index (SDI) for an individualmaterial or composite of materials. The scope of the ASTM E84 test standard is limited to providingthe characteristics of the material’s surface flammability on a 24-ft long sample installed in the testapparatus tunnel.ASTM E119 is the fire resistance test of an assembly that may be constructed with eithernoncombustible or combustible materials, depending on the materials allowed for that type ofconstruction. The test specimens are most typically walls, floors and structural steel. The testevaluates the ability of a construction element to prevent passage of fire from the fire side ofthe assembly to the non-fire side, and to prevent excessive thermal transmission through theelements. The result of an ASTM E119 test is expressed in terms of a period, such as 1-hour, 2-hour,etc., for which the test assembly meets the performance criteria of the test. The results of an ASTME119 test have no relation to the combustibility of the individual components of the test assembly.HOW TO PROPERLY TESTACCORDING TO ASTM E136The test standard for noncombustibility is titled: ASTM E136 Standard Test Method for AssessingCombustibility of Materials Using a Vertical Tube Furnace at 750 C, published by ASTM International.The furnace consists of a ceramic core and an electric heating coil and the current is set to establishan internal temperature of 750 C (1382 F). The prepared sample is placed inside the furnace and thetemperatures are continuously measured at the surface and in the center of the specimen using twoindependent thermocouples.Once the sample temperature reaches 750 C(1382 F), any temperature rise above the setfurnace temperature is attributed to the burningof material from the sample itself. The sampleprovides the fuel for the temperature rise. SeeFigure 1 for the location of the thermocoupleplacement.Section 8.7.2 notes that the test is continued untilthe temperatures at thermocouples T3 and T4have reached maxima, or until it is evident that thespecimen does not pass this test (as defined below).As per the standard, the test duration is not fixed at30 minutes, the test must be run for a minimum of30 minutes.Section 4.1 This test method uses a furnace toexpose building materials to a temperature of750 C (1382 F) until failure occurs or for at least30 minutes.In fact, the test shall continue beyond 30 minutes untilsuch time as 10 minutes elapse since the last time thetemperature measured at the center thermocouple T3rose by at least 1 C in any one minute.Figure 1 - Vertical Tube Furnace LocatingT3 & T4 SensorsSection 8.7.3 After 30 minutes of testing have elapsed, or at any time subsequent to that, testing shallbe discontinued if, over the previous 10 minutes, the temperature measured at the center thermocoupleT3 has risen by no more than 1 C in any one minute. The final temperature reading shall be recorded asthe maximum temperature.2

HOW TO PROPERLY TESTACCORDING TO ASTM E136, CONT.The procedure is repeated with four identical test specimens, and the material passes the test if atleast three of the four test specimens tested meet both of the two individual test specimen criteria.The weight of the specimen is measured before and after the test, to determine the weight lossduring the test. There are different pass criteria if more or less than 50% of the sample material islost.All samples tested lost less than 50% of their weight, therefore the test criteria for passing thestandard per Section 15 is as follows:Section 15.2.1 The recorded temperature of the surface and interior thermocouples do not, atany time during the test, rise more than 30 C (54 F) above the stabilized furnace temperature.Section 15.2.2 There is no flaming from the specimen after 30 seconds.Per Section X1.5.1.1 Commentary of ASTM E136, any building material exceeding 3% combustibleportion in a noncombustible material is very likely to fail the noncombustibility test.Based on a series of tests on a wide variety of materials, a 30-second flame duration and a 30 C(54 F) rise were proposed as two criteria that could help to distinguish between clearly combustibleand clearly noncombustible materials. The results of these tests indicated that the proposed levelswould limit the combustible portion of noncombustible materials to a maximum of 3%.Based on this composition criteria, before they were even tested, it is very likely that none of theMgO structural panels tested and analyzed in this white paper would pass the ASTM E136 test fornoncombustibility.The following graph (Figure 2) reflects the constituent analysis of the Total Organic Carbon (TOC)content of the four (4) MgO structural panels tested.Total Organic Carbon (TOC) Content for Four MgO structural panelsand USG Structural PanelAverage Total Organic Carbon, Wt %RESULTS OF TESTING108643%20USG RD0.833.615.437.295.09Figure 2 - Total Organic Carbon Content of All Panels Tested3

USG obtained results of third-party testing of the four (4) MgO structural panels. The four (4)products were submitted and labeled A,B,C, and D. The laboratory did not know the brand orproduct names of the four (4) MgO structural panels submitted. The four (4) MgO structural panelswere tested between May 4th and May 8th, 2020 and the final report with the test results waspresented to USG on the 15th of the same month.All four (4) samples for each of the MgO structural panels failed ASTM E136, in that every sampletested attained a maxima at a level substantially higher than the 780 C (1436 F) failure thresholdof the standard. The results of the four (4) samples for each of the T3 & T4 sensors, for the four (4)panels tested are shown below in the individual product graphs.ASTM E136 NOCOM Test Samples120011001000900Temperature in degrees CASTM E136 TESTING800Maximum Allowed 780 C700600T3 #1500T3 #2T3 #3400T3 #4T4 #1300T4 #2T4 #3T4 #4200Failure1000Time(minutes) 0102030405060Figure 3 - NOCOM Time/Temperature Curves4

ASTM E136 TESTING, CONT.ASTM E136 Dragonboard Test Samples120011001000Temperature in degrees C900800Maximum Allowed 780 C700600T3 #1500T3 #2T3 #3400T3 #4T4 #1300T4 #2T4 #3T4 #4200Failure1000Time(minutes) 01020304050605060Figure 4 - Dragonboard Time/Temperature CurvesASTM E136 extremegreen Test Samples120011001000Temperature in degrees C900800Maximum Allowed 780 C700600T3 #1500T3 #2T3 #3400T3 #4T4 #1300T4 #2T4 #3T4 #4200Failure1000Time(minutes) 01020Figure 5 - extremegreen Time/Temperature Curves30405

ASTM E136 TESTING, CONT.ASTM E136 MEGABOARD Test Samples120011001000Temperature in degrees C900800Maximum Allowed 780 C700600T3 #1500T3 #2T3 #3400T3 #4T4 #1300T4 #2T4 #3T4 #4200Failure1000Time(minutes) 0102030405060Figure 6 - MEGABOARD Time/Temperature CurvesPlease note that the tests were performed for the minimum 30 minutes and continued untilthe interior thermocouples attained a maxima. The maxima for each MgO structural panel aresummarized in Figure 7. Again, any temperature maximum over 780 C (1436 F) is a failure.AverageMaximum 0 C (1544 F)1002 C (1836 F)1042 C (1908 F)971 C (1780 F)Figure 7 – Average Maximum Temperatures Attained for Four (4) Samples of Each TestedAfter testing, each sample was weighed, and the percentage of material lost is summarized in Figure 8.Weight LossNOCOMDragonboardextremegreenMEGABOARDSample 131%42%41%43%Sample 231%42%42%43%Sample 333%42%42%43%Sample 432%43%42%42%Figure 8 – Percentage of Material Lost for Four (4) Samples of Each Tested6

THE “SUPPORT” OFFERED FOR CLAIMSOF NONCOMBUSTIBILITYThose associated with the manufacture and sale of NOCOM, Dragonboard, extremegreen andMEGABOARD may point to code reports and outdated test reports that they suggest support theirclaims of noncombustibility. However, those reports either relate to panels of different thicknessesor failed to provide adequate detail supporting their conclusions.NOCOMProduct Code Report ICC ESR-4268 categorizes the NOCOM panel as falling under Section 09 2815 of the MasterSpec Format titled “Fibered Gypsum Backing Boards,” as opposed to Section 06 1213 titled “Cementitious Structural Sheathing,” which would apply to structural panels.Under the heading “USES,” this report explains that “NOCOM is used on interior surfaces as definedin the IBC Section 2502, as substrate sheets suitable for decoration with paint, wallpaper, ceramictile, natural stone or dimension stone on walls in interior dry areas and on walls and ceilings aspermitted in IBC Section 2509.2.” Chapter 25 of the IBC is entitled: “Gypsum Board, GypsumPanel Products and Plaster.” Thus, the report makes clear that NOCOM’s intended “use” is not as astructural subfloor or roof deck panel.The report notes under the “DESCRIPTION” heading that its conclusions are only intended to cover1/2", 3/8" and 5/8" thick panels, not 3/4" or larger structural panels. Ameriform, the sales agent forNOCOM, notes on its website that: “Scope of this report does not include 3/4" thickness or floorapplications at this time,” although a link to the report is located on Ameriform’s Tech Docs pagefor subfloor structural panels.Lastly, ICC ESR-4268 notes in Sections 5.5 and 5.8 that the “use of NOCOM as floor sheathingor floor underlayment or in horizontal diaphragms is outside of the scope of this report.” Analysisof the floor diaphragm capacities would be a requirement relevant to the use of the panel as asubfloor.Because the ESR-4268 report does not assess the noncombustibility of 3/4" structural panels, itdoes not support the conclusion that NOCOM 3/4" structural panels are noncombustible. As shownin Figure 3 of this white paper, testing of commercially available NOCOM 3/4" structural panels,conducted by an independent laboratory in 2020, indicates that they are not noncombustible.DragonboardDragonboard is a magnesium oxide panel manufactured in China. Unverified specimens ofDragonboard were tested 13 years ago in December of 2007 at Southwest Research (reportnumber: 01.13544.01.313) in accordance with ASTM E136-04. The test report Southwest generated(“the report”) specifically notes that “(t)he results presented in this report apply specifically tothe specimens tested, in the manner tested, and not to the entire production of these or similarmaterials, ” The report further explains that “Dragonboard provided four pieces of the material,identified as Dragonboard Sheathing.”The report identifies no quality control or follow-up service procedure allowing for verificationthat the specimens tested were, in fact, commercially available Dragonboard. The testing facilitydoes not refer to any witnessed production of the samples or any chain of custody from themanufacturing facility in China to the testing laboratory in the United States. The report simplyindicates that “Dragonboard” presented some samples of a product. As shown in Figure 4 of thiswhite paper, testing of commercially available 3/4" structural Dragonboard panels, conducted byan independent laboratory in 2020, indicates that they are not noncombustible.Of related interest is the fact that, according to the report, one of the four tested samples ignitedat 25:30 (after 25 minutes and 30 seconds exposure to the test furnace) and continued to burnuntil the end of the test. While the report indicates that the other three specimens purported to beDragonboard passed the test, the outlier specimen’s maximum temperature reached 958 C, wellover the ASTM E136 780 C failure criteria.extremegreenICC NTA Evaluation Report NER-1031 (“the report”) evaluates the extremegreen magnesium oxidepanel, which is produced in Nantong, China. Again, the report evaluates only 1/2" panels. In fact,Section 7.1.1 of the report specifically notes that “(t)his report applies only to the board thicknessspecifically listed herein.”Although the report deems the 1/2" extremegreen panel to be a noncombustible building element,Section 8 (“EVIDENCE SUBMITTED”) does not identify ASTM E136 as one of the standards againstwhich the panel was tested. Without testing to the ASTM E136 standard, it is unclear how adetermination of noncombustibility could have been reached (even with respect to a 1/2" panel).7

THE “SUPPORT” OFFERED FOR CLAIMSOF NONCOMBUSTIBILITY, CONT.Structural designers will note that Section 5.2 of the report (titled “Permanent Loads”) reduces thepanel capacities listed in Table 1 to 50% of their listed values when loads of long duration such aspermanent loads are applied. No other panel has this restriction.The report provides no information with respect to the noncombustibility of the 3/4" or thickerextremegreen structural panels, such as would be used as structural panels in Types I andII construction. Because the NER-1031 report does not assess the noncombustibility of 3/4"structural panels, it does not support the conclusion that extremegreen 3/4" structural panelsare noncombustible. As shown in Figure 5 of this white paper, testing of commercially availableextremegreen 3/4" structural panels, conducted by an independent laboratory in 2020, indicatesthat they are not noncombustible.MEGABOARDReport ESL-1151 (“the report”) covers MEGABOARD which is manufactured in Jianzhou, Qingdao,Shangdong, China. MEGABOARD is categorized in the report under MasterFormat Section 09 0000 FINISHES; specifically, 09 28 15 titled “Fibered Gypsum Backing Boards,” as opposed to Section06 12 13 titled “Cementitious Structural Sheathing” which would apply to structural panels.The report specifically notes in the “Condition of Listing” (note #3) that “the listing report appliesonly to the materials tested and as submitted for review by ICC-ES.” As was the case with the othertest reports referenced above, the ESL-1151 report contains no reference to chain of custody withrespect to the specimens submitted for review.As shown in Figure 6 of this white paper, testing by an independent laboratory in 2020 indicatesthat MEGABOARD panels purchased in the marketplace were clearly not combustible per ASTME136.USG procured NOCOM, Dragonboard, extremegreen and MEGABOARD panels in the openmarketplace and subjected them to ASTM E136 noncombustibility testing by an independent,third-party laboratory. See results summarized in Figure 9.E136 Average of T3 Samples120011001000900Temperature in degrees CCONCLUSION800Maximum Allowed 780 300Failure2001000Time(minutes) 0102030405060Figure 9 - ASTM E136 T3 Sensors Average Time/Temperature Curve8

CONCLUSION, CONT.The 2012, 2015 and 2018 IBC model codes indicate that MgO subfloor and roof deck “buildingelements” in Types I and II construction must be noncombustible in accordance with ASTM E136.USG’s 3/4" Structural Panels consistently pass the ASTM E136 test.The results of the testing conducted in 2020 by an independent, third-party laboratory have shownthat NOCOM, Dragonboard, extremegreen and MEGABOARD 3/4" structural panels do not meet therequirements of ASTM E136 to qualify as noncombustible structural building elements. Designers,contractors, distributors and owners should be aware that any claims of noncombustibility made bymanufacturers of these four (4) 3/4" MgO structural panels, as sold in the market today, (i.e., claimsthat these panels are capable of passing an unmodified ASTM E136 test) are simply not accurate.REFERENCES1. Per 2012, 2015 and 2018 International Building Code 2. Per Jensen Hughes Letter dated November 16, 2018 commissioned by USG3. Per ASTM E136 – 19 Standard Test Method for Assessing Combustibility o