Hempcrete scores a perfect ‘O’ under ASTM fire testing in USA

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Hempcrete’s perfect performance in recent fire resistance tests in the USA can help move the material one step closer to acceptance after samples put together by U.S. hemp builder Hempitecture scored perfectly in analysis carried out by ASTM, the international standards organization. 

Hempitecture announced the development in a post last week, urging other hemp builders to use the results in their efforts to convince permitting officials and regulators to look more favorably on hempcrete.

The holdup

Lack of testing “has been holding us back from truly being able to call hempcrete the fireproof material that it actually is, here in the U.S.,” Hempitecture said in the post. Results from the specific test, ASTM E 84-19B, are recognized by building code officials and regulators in their safety analyses of a range of building materials. 

“We have faced the disadvantage of little to no U.S. based testing on the mechanical and performance properties of the material,” Hempitecture noted, adding that documentation from other countries has not proven sufficient in the U.S. building environment.

Laws of physics

“Much resistance has been put up by local building inspectors and permitting agencies. As though the laws of physics are different in the countries that hempcrete has been previously tested in. These documents do not suffice for arguing hempcrete’s flame resistance here in the U.S,” Hempitecture said.

The company also posted a facsimile of ASTM’s test results, dated Feb. 15, 2020, which showed hempcrete’s performance reaching a perfect score on the tests. Under “Flamespread” and “Smoke Developed” indices, hempcrete scored “0,” the highest possible rating on a scale of 0 to 450.

Performance could vary

While Hempitecture prepared the hempcrete specimens for the recent tests from its own materials, the company noted that variables such as hurd type and binder could affect the performance of other hempcrete mixtures under ASTM E 84-19B testing.

ASTM is one of the largest voluntary standards developing bodies in the world, and provides a forum for the development of consensus standards for materials, products, systems and services. Members represent producers, consumers, government, and academia from more than 140 countries.

“The results were not surprising for us, but they were for the testing agency,” Hempitecture said. “They reported back that the only material they have seen perform this well in the past is mineral wool.”

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