Hempcrete Certification

The US Hemp Building Association Embarks on the Path Towards “Hempcrete” Certification for Large Scale Use

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.

Certification Challenges

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.

Who Approves Certification?

The International Code Council 

The ICC will determine how Hempcrete can be used in a building. 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. 

The American Society for Testing & Materials

ASTM will determine what hempcrete is and how to measure its performance. 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.

How to Take Action

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.

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Major steps taken

Committee Formed & Contacts Made

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).

The Hemp Entrepreneur Podcast Interview of Tai Olson


USHBA member, Cameron McIntosh of Americhanvre, interviewed Tai Olson and Dion Markgraaff to discuss the steps that are being made to get hemp-lime construction standards written under ASTM guidelines and approved by the International Code Council to make it easier for hemp-lime to be permitted anywhere in the U.S.

Listen to Podcast

USHBA Featured in ASTM Certification Article

“Ask someone to name a product containing hemp and most likely, he or she will mention consumables or clothing. Yet for centuries, humankind has used the Cannabis sativa plant’s woody stem in construction projects, breaking it into pieces and mixing it with lime and water to create an insulative, non-load-bearing material. Over the years, this nontoxic substance has been called hemp-lime or hemp concrete. Today it’s called hempcrete. “

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