White paper By Dion Markgraaff and the USHBA Education Committee

Q: If hemp is so great for construction, why is it not in every building already?

A: Certification issues

Shortly after the US Hemp Building Association was started in July 2019, the need for certification of the building materials was one of the first issues this group knew they needed to address for the benefit of all the members. The first steps started by The USHBA Education Committee was organizing, meeting, and planning the course of action needed to achieve the critical goal of internationally recognized certification of hemp/lime building, more popularly known as “hempcrete”. Chaired by Sergi Kovalenko of the internationally renowned building company Hempire, the committee plans to publish the issues and document the process needed to obtain hempcrete certification as soon as possible.

The second fortunate step was to network and attract into the committee, a top expert on this subject, USHBA member, Tai Olson, of the U.S. Heritage Group, a leader in hempcrete construction for many years who has supported over half of the hempcrete builds in the United States. His knowledge and experience in this area makes him the logical person to lead the technical part of this industry game changing project.

A summary of the issues by Olson;

Hempcrete has an issue with permitting in the US due to one of the basic core functions of a Hempcrete structure. Hempcrete is meant to be a vapor-permeable wall system that will allow the passive transmission of moisture vapor through the wall to improve the thermal performance of the structure and create a better indoor air environment. However, US buildings are designed with a different standpoint on permeability and the building standards differ from the European building standards where the hempcrete system was developed.

There are two groups that need to be engaged to certify Hempcrete as a building material in the US: The International Code Council (ICC) and American Society for Testing and Materials (ASTM). The ICC provides standards for building systems, while ASTM provides standards for individual products. This means that the ICC will determine how Hempcrete can be used in a building while ASTM will determine what hempcrete is and how to measure its performance.
Current ICC codes typically require the use of vapor barriers in the building envelope and impermeable sheathing as structural bracing. Both elements impede the performance of hempcrete and should be avoided for best results. Fortunately, the ICC includes code appendixes that account for systems with high permeability requirements. “Straw Bale” and “Light Straw-Clay” Construction both have special building code standards added to the ICC and have similar permeability requirements as Hempcrete. This provides a roadmap for the certification of Hempcrete under ICC requirements. There currently exist ASTM standards for the testing of thermal, fire and permeability characteristics of building materials which can be applied to hempcrete. However, ASTM specifications need to be developed to define what is considered hempcrete for construction purposes. This will require standards to be developed defining the physical characteristics of the hurd and the binder, as well as performance standards that do not fit into the existing ASTM testing standards.

The USHBA needs to engage the ICC and ASTM to establish the building standards for Hempcrete in order to solve the permitting and performance issues that have prevented Hempcrete from gaining a larger presence in the US. While the exact cost of this process is yet to be determined, initial estimates are $20,000-50,000 for ASTM certification and $300,000-500,000 for ICC accreditation. With effective fundraising and grants from local and state organizations, Hempcrete can undergo accreditation and be ready for widespread use within the year.


An excellent summary about these issues is on The Hemp Entrepreneur Podcast by USHBA member Cameron McIntosh of Americhanvre, interviewing Mr. Olson

The 2020 Path(s) – ASTM and ICC are 2 streets to go down at the same time

The USHBA education committee is focused on achieving this critical industry goal of hempcrete certifications. Therefore, we have created a separate dedicated committee within the USHBA to work only on the various aspects, and publishing ways stakeholders and USHBA members can help. Money, time/work, and technical skills are needed to be incorporated into the process. This Certification Committee will be divided into two working groups to collaborate with both ASTM and ICC at the same time. The USHBA will post regular updates through our social media and members can join monthly calls on the work being done.

The USHBA Education committee invited ASTM into our meetings. Charles P. Rutherford, II, of CPR Squared, Inc., is an ASTM strategy and standards development consultant to support standards development and related activities for the organization’s cannabis committee (D37) and  Darwin Millard, a botanical extraction specialist at Millard Masonek Solutions, LLC, who is the Hemp Liaison to ASTM Committee D37, Vice-Chair of ASTM Subcommittee D37.04 on Processing and Handling, and Co-Chair of ASTM Subcommittee D37.07 on Hemp, joined and advised the group. After a couple conference calls, a huge historic step occurred through these efforts. ASTM, with assistance from the USHBA, has started an official section in ASTM for “hempcrete”. Together, the collective recommendation was to appoint Tai Olson to be the Technical Contact of two ASTM hempcrete working groups under the cannabis committee (D37).

ASTM Press Release

Cannabis Committee Seeks Help Developing Hempcrete Standards
W. CONSHOHOCKEN, Pa., Dec., 2019 – ASTM International’s cannabis committee (D37) is inviting interested parties to help develop two proposed standards for using hempcrete in construction. Hempcrete is a bio-composite material mixture of hemp hurds and lime that is used as a material for construction and insulation. Specifically, the proposed standards (WK70549 and WK70550) focus on testing procedures for measuring fire resistance and R-value (the capacity of an insulating material to resist heat flow) for hempcrete construction materials.
According to Tai Olson, one of the proposed standards aims to review existing ASTM International test methods for R-value and fire resistance to evaluate their appropriateness for hempcrete, while the other proposed standard will be used for establishing unbiased R-value and fire resistance properties for hempcrete insulation materials. Manufacturers, laboratories, architects, contractors, and regulatory bodies, especially permitting offices, could be the primary users of the proposed standards, Olson notes.
For more information on ASTM International’s cannabis committee, please watch this video ( https://www.youtube.com/watch?v=Pdo5WWoLBiE&amp=&feature=emb_logo). ASTM welcomes participation in the development of its standards. Become a member at www.astm.org/JOIN. The next meeting of the cannabis committee is February 2-4 in Atlanta, Georgia, USA. There will be an hour and a half for the USHBA to meet with the D37.07 membership and work through any areas of the project that make sense given the audience during our upcoming committee week in Atlanta, GA (Feb. 2nd through the 4th). The meeting time is from 8 AM to 9:30 AM ET, February 4th.

About ASTM International
Committed to serving global societal needs, ASTM International positively impacts public health and safety, consumer confidence, and overall quality of life. We integrate consensus standards – developed with our international membership of volunteer technical experts – and innovative services to improve lives… Helping our world work better.

The two different ASTM work items are organized underneath the D37.07 and will focus on different aspects of the issue – one on analysis of current test methods and one on the chosen methods to measure the insulation value and the fire resistance of hempcrete.

WK70549 – Test Methods For Evaluating the Appropriateness/Applicability of Current R-value and Fire Resistance Test Methods to Testing the Insulative Properties of Hempcrete Insulation Samples

Proposed Scope: Conduct a review of the existing ASTM test methods for R-value and Fire Resistance and evaluate them for their appropriateness/applicability to testing hempcrete insulation and identify recommended changes to the test methods to make them more appropriate/applicable to testing hempcrete insulation.

Rationale: An evaluation of the existing test methods for R-value and Fire Resistance must be done to determine if the existing test methods are appropriate/applicable to testing hempcrete insulation materials. After a review of the current test methods, it be determined if new test methods must be developed to more accurately quantify the insulative properties of hempcrete insulation materials. Only after the appropriate/applicable testing methods have been identified, or the required modifications to them, can these test methods be used to establish unbiased R-value and Fire Resistance data that can be used to create performance specifications for hempcrete insulation. This working group will perform this review and make recommended changes to test methods as necessary.

Existing Standards: Potentially none. A thorough evaluation of the existing test methods must be performed in order to begin the development of a performance specification for hempcrete insulation. Without the test methods there are no means to accurately determine the R-value and Fire Resistance of hempcrete insulation materials.

WK70550 – Test Method For Establishing Unbiased R-value and Fire Resistance Properties of Hempcrete Insulation Materials

Proposed Scope: Create an R&D protocol designed with the end goal of establishing unbiased R-value and Fire Resistance data that can be used to create a performance specification for hempcrete insulation. This working group shall work with the R-value and Fire Resistance Test Method Evaluation Working Group (WK70549) to define the test methods that shall be used in the R&D protocol. This working group shall work with ASTMs Inter Laboratory Studies (ILS) program to coordinate the testing effort and perform the data analysis. This group shall also work with other ASTM technical committees and organizations having a vested interest.

Rationale: Hempcrete is an eco-friendly construction material that can be made into an insulation material. The process for manufacturing hempcrete varies from region to region making it difficult, if not impossible, to create a specification for the composition of this material. Therefore, a performance specification is necessary to qualify the insulative properties of a hempcrete insulation material. Performance specifications will allow for hempcrete manufacturers to produce hempcrete in any way they see fit using any number of aggregates or binders, and make it easier for hemp-building projects to get permitted and pass inspection, so long as the hempcrete meets the insulation performance specification. This working group will generate the unbiased data necessary to establish the average R-value and Fire Resistance of hempcrete insulation that shall be used as the foundation for a hempcrete insulation performance specification.

Existing Standards: R-value and Fire Resistance vary based on the composition of the hempcrete insulation material. Due to this variance, there are no established values for the insulative properties of hempcrete insulation. This working group will rectify this situation by developing an open and consensus drive approach to the establishment of internationally recognized average R-value and Fire Resistance performance specifications for hempcrete insulation.


Mr. Millard says, “Technically the second work item (WK70550), will define a protocol that will be used to solicit hempcrete insulation material samples from various different hempcrete insulation material manufacturers to be tested against the methods identified by the first work item (WK70549), and then analyze the data that is generated from the tests. The second work item will not define the performance specifications directly, but it will generate unbiased data that can be used to establish the performance specifications.”

This process will need companies from around the world to participate and contribute with data, samples, and money. Millard states, “There will be no fee attributed to an ‘ASTM’ certification because ASTM does not certify anyone or anything; a third-party normally does that, in this case, the ICC-ES. What might cost money is the testing that will be required and then the data analysis once the testing is complete.”

Update on these exciting developments and other information will be published constantly by ASTM committee and by the USHBA so everyone will be able to follow the progress and promote the completion of the goals. Plus, anyone can join the ASTM and get a vote on the final outcome.

The USHBA’s role in this partnership is to bring attention, funding, and to solicit technical collaboration of samples from companies around the world who are using this composite material (hemp, water, lime, and/or other minerals) with the technology (the ratios and formulations). This will provide the raw data needed to test and document their performance for establishment of certification of hempcrete. Mr. Millard says, “ASTM doesn’t officially certify a material. The role of ASTM is to provide the tools for its membership to develop consensus standards and a certification organization will test against it.”

At the same time as ASTM process is going on, the USHBA has been reaching out and strategizing about the International Code Council (ICC) iccsafe.org certification. According to their website, “The International Code Council is a nonprofit association that provides a wide range of building safety solutions including product evaluation, accreditation, certification, codification and training. It develops model codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.”

Due to the cost of the ICC’s process, this certification goal has a major funding issue at its core. Confidence in the properties of hemp and lime technology are great, being proven in Europe and around the world, but the $300,000 – $500,000 estimated cost of ICC accreditation and certification is, at the moment, way beyond the means of small-scale businesses in the industry.

Working with the USHBA and collectively with companies in the industry, the hope is to reduce these estimated costs. According to other projections, “The ICC-ES process will actually only cost $25,000 to $50,000 to complete for each new building material seeking certification. Depending on the number of different types of hempcrete insulation being evaluated, your estimate of $300k to $500k may or may not be accurate.”

Government and institutional funds are a more realistic option for whatever the large price is going to be. The aim of the USHBA certification committee’s upcoming informational campaign is to increase the awareness and raise funding towards paying this bill. The USHBA is setting a separate non-profit C3 fund dedicated to raising these funds. Getting over this industry hurdle will open code compliance and widespread use of “hempcrete”. The construction industry is $1.3 Trillion in the USA per year, so there is an abundance of energy to tap into.

Strawbale building has shown the way, and recently replicated by the cob building industry, which have been added into the ICC codes of certification. An excellent article how it happened is here; (https://www.strawbuilding.org/Resources/Documents/Strawbale_Construction_Building_Codes.pdf) There are “Strawbale construction—a wall system using baled straw as large, stackable blocks—was invented in the United States more than 130 years ago. Though its original heyday was in the early 20th century, a vigorous revival began in the late 1980s and continues today. The result is thousands of strawbale buildings spread across 49 states—more than 500 in California alone—and many thousands more in over 45 countries around the world.”

In addition to the superior performance hempcrete construction brings in many respects (ie. fire, bug, mold, and earthquake resistance; humidity regulation; thermal energy saving performance), this carbon sequestering, recyclable/compostable material can solve 2 of the construction industry’s biggest problems – CO2 emissions and waste – overnight; creating a huge opportunity for sustainable economic growth in the construction industry going forward.

Hemp is our best hope. The USHBA members are excited about the opportunities this developing industry brings, and impatient for the next steps to bring better construction products to markets. The goal is hempcrete certification in 2020 – lets get it done!