Advancing the Hemp Building Industry: Q&A with the US Hemp Building Association


At the beginning of January, the American Hemp Building Association (USHBA) has taken a step towards advancing the industry by submitting hemp lime insulation (hempcrete) for certification in US building codes.

© Courtesy of USHBA


Jacob Waddell, acting executive director of the USHBA, said hempcrete insulation is a “mixture of hemp flock with a lime binder [that] essentially creates a monolithic wall system. If certification is approved, hempcrete will be allowed as a standard material for residential construction.

Here, Waddell outlines the application process, what certification would mean for the industry, the challenges it would help solve, the opportunities it would present, and more.

Andriana Ruscitto: For those who may not know, can you tell us a bit about what the USHBA does?

Jacob Waddell: The American Hemp Building Association [was] formed to help support and advance the hemp building industry. Right now, we’re doing that by trying to establish codes and standards for the industry, as well as educating people and starting a workforce development process.

AR: What are the main areas of intervention of the organization? Does the organization only focus on using hemp as a building material?

JW: Yes, it is entirely, solely focused on hemp as a building material. It can be basically any building-related product, but [currently includes] hemp wood, hemp batt insulation and hemp concrete in its various forms, or hemp lime in its various forms.

AR: Can you briefly describe the US building codes?

JW: Codes in the United States are heavily fragmented. Decisions about whether a building can be erected can vary from county to county, or even from permitting officer to permitting officer. Now, it’s because of the judgment calls. So with that kind of divided sense there’s a bunch of people [who make up] the International Code Council (ICC), which essentially defines the recommended building codes for the United States. The International Code Council [is] divided into 15 [modern building safety codes]. Two of those who [are] our main interest is the IRC, the International residential codeand the IBC, which is the international building code. we just submitted [hempcrete to] the residential code. The building code is essentially a commercial code. So we submitted it to the IRC, which is a subsection of the ICC.

AR: What will this certification bring to the hemp building industry? What challenges or issues will this help solve for construction projects looking to use hempcrete?

JW: Residential codes describe what is allowed on residential buildings. Now, buildings have been built with hemp concrete without being in the residential code because there is an allowance for a deviation; it’s an alternate hardware spread. It takes time and you [have to prove] release your material for people to accept. Even then, it is essentially up to the licensing officer to decide whether [they] let it go or not. So, by establishing ourselves in the building codes, the hope is to avoid deviations and delays in projects caused by the use of hemp concrete as a material or hemp lime as a material. This is the purpose of submission.

As an industry, really, to outgrow and grow, we have to get to a point where big developers and big companies feel comfortable doing business in our environment. Having an extra three months in your planning because you’re using this hardware won’t work for most businesses considering large scale. This can work from project to project, but if people are building large amounts of buildings, they won’t want to focus on this detail. [for] each project. So the hope is to reduce the risk of entry for people who build with this material and make it more viable. And that’s so much what we’re doing right now, we’re just trying to clean up things that can mitigate risk for companies entering our industry.

This opens up both the possibility of easy access for the smallest builder to be able to build with this material, [and] it also opens access to the tallest builder to remove an obstacle. So… it helps everyone, but for different reasons.

AR: Can you briefly walk me through the application process of what it took to submit hempcrete for certification in US building codes?

JW: Basically, we had to write an appendix for the IRC. We used two consultants: Martin Hammer and David Eisenberg, who developed the IRC appendices for straw bale, straw-clay, small housesand ear [monolithic adobe]. … We had meetings with them and [worked with] a group of what started out as three, then ended up being a six-member team. … Many of us have been in over a hundred hours of meetings over three months, going through this line by line, writing things down, rewriting them, correcting them, trying to make them accessible to the language coded, trying to ask the things we had to ask, leaving out the things we couldn’t prove with enough data. This [took] about three months from the beginning of October.

AR: Now that the certification has been filed, what happens next?

JW: So there’s the committee hearing at the end of March [or] early April, then there will be a public comment period. [After that], there will be another hearing in September. And then, in October, government officials make a final decision.

AR: So, if this certification passes, do we envisage around 2024 the use of hemp concrete as a construction material without any additional approval?

JW: Yes and no. Yes, they will be in the code. Then at that point we come back to the fact that we have a very fragmented system in the United States. So even after getting into the codes we will have to appeal to different states and maybe even counties to allow this but it will be a [much] easier argument if it’s in the building code.

I know most or some counties just accept the building code. …So the first step is to get that approved, and then … the next step will be to lobby different states to approve it outright based on the submission.

AR: What processes or tests does hempcrete need to pass to be certified to US building codes?

JW: Basically, this was put in place as an insulator; this is how the code is written. For insulating materials, you must prove your insulating power, as well as your fire propagation. Now we’ve had test results with fire spread that basically give you a score of zero. So fire spread was something you have to prove, and we were able to prove it and feel extremely comfortable with it.

Editor’s note: A “fire spread” test, also called American Society for Testing and Materials [ASTM] E84, is used to assess the fire behavior of building materials used for interior wall and ceiling finishes. The results of these tests are measured by Flame Spread Index (SFI) and Smoke Development Index (SDI), and each building material is assigned a standard class based on the results, according to Applied laboratory.

A flame spread score of 0-25, also known as Class 1 or Class A, means that the material of construction will adequately limit the spread of fire. In this case, the score of zero for hempcrete insulation is preferred, over maple wood, which scored a score of 104 (class C or 3) based on this graphic.

The insulating value, like the other point, was taken from the data we [compiled] from all over the world and [put] in a table, then [it] gives another option to run your own ASTM tests that are approved by the Federal Trade Commission.

AR: What opportunities will this certification present for the hemp industry as a whole?

JW: For the hemp industry as a whole, hopefully we will lower some barriers for usage applications so that we can continue to grow and become bigger entities in this space. In reality, if we don’t have a consumer buying the finished hemp products, there’s no reason for a farmer to grow it or a processor to process it. So we focus on finished products, making them viable, [and] develop those markets so that we can then pull demand from the bottom of the chain.

AR: Is there anything I forgot or that you think would be beneficial to add or include?

JW: This is just another step in a very long process to grow this industry in a safe and robust way.

Editor’s Note: This story has been edited for style, length, and clarity.


Comments are closed.