‘There is a modern path for renewable, plant-based materials like hempcrete to follow’

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INTERVIEW: Cameron McIntosh is co-founder of Americhanvre Cast Hemp, a Pennsylvania hemp building company that is the exclusive U.S. licensee of the Baumer Ereasy Spray Applied Hempcrete system of France. McIntosh, who has a background in operations management, was a co-author of the recently approved International Residential Code Council’s appendix on hempcrete. He is a former member of the board of directors and corporate sponsor of the US Hemp Building Association, and a current member of the board of directors of the Pennsylvania Hemp Industry Council.

HempToday: What’s really needed to get hempcrete construction more firmly into the green building movement and into the broader construction industry?

Cameron McIntosh: Testing, documentation and education are the easy answers, but there is a modern path for renewable, annual agricultural, plant-based materials like hempcrete to follow.  Environmental product declarations, or EPD’s, are a mechanism for formally establishing the actual carbon sequestration value of a given construction material in a language that allows for those carbon benefits to be formally recognized by design professionals who specify construction materials.

In order to have robust EPD’s, we must first have Product Category Rules (PCR’s) that define the parameters for creating an EPD for an individual product.  In the northeast, a movement has sprouted, led by MASS design group and New Frameworks, to rally multidisciplinary stakeholders around the effort to establish annual renewable plant-based materials like straw and hemp in the American construction vernacular.

This effort is underpinned by another led by the California Strawbale Association, or CASBA, on the West Coast, who have undertaken the effort to rally those same stakeholders around the creation of PCR’s for these types of materials. These efforts are aimed at growing awareness/education and definition around sustainable building materials via collaboration across the various input material types with the common threads of sustainability, renewability and carbon sequestration. This type of collaboration is new in the green building space and is just exactly what we need to ensure that this renaissance of renewable and carbon-sequestering materials continues to build momentum, to the benefit of humanity and our planet.

HT: How far are we away from getting hempcrete into commercial code applications? How much time? How many years?

CM: We really are on the precipice of completing the work to be recognized by international commercial code with one of the largest (and most expensive) dominos falling here with our ASTM E-119 fire under load testing. This grant will allow us to create the first U.S. data points on the performance of a hempcrete wall assembly in a full-scale test for E-119.  

Although the method and material will be specific to the Ereasy system, for all intents and purposes it will be the first full-scale demonstration of hempcrete via this testing.  It is difficult to put an exact timeline on hempcrete being recognized in the IBC, however, USHBA has continued to work with the same group of consultants engaged for the original IRC submission – Martin Hammer, David Eisenberg and Anthony Dente – to formulate our approach to translating that work into the IBC.  According to this group of consultants, the ASTM E-119 testing is the most critical next step in this line of work.

HT: Who are your clients and how did they come to you? Are there common characteristics or attitudes among those who have come to understand and appreciate hemp as a building solution?

CM: Many of Americhanvre’s clients can be categorized as motivated, capable homeowner builders who have taken it upon themselves to manage the construction of their new home.  As such, they are able to save a good deal of money in being their own general contractor, however, this often costs them in terms of the time it takes to complete the home. 

Although they are their own general contractors, our clients do subcontract for aspects of the build that are outside of their capabilities, such as installation of the hempcrete via the Ereasy system. Most all of our clients are drawn to the performance and cost of ownership benefits with material health as their second largest motivation.  

Surprisingly, they do not often fit the mold of being categorized as “cannabis enthusiasts” – they have diverse professional, and even religious, backgrounds and are drawn to the tangible benefits of the material, not just the sex appeal of hemp!

HT: What percentage of your projects are retrofits, and what percentage are new builds? What do you consider your marquee projects in each category? Briefly describe those, please.

CM:  I would say that the majority, maybe 80%, of our installations are for custom, one-of-a-kind, new build residential homes and that 20% are for retrofits of varying scope and size. Our Ereasy system owner-operators, Hall & Moskow, in Newburyport, MA who have utilized the system in conjunction with a full-section, tilt-up panel construction method of their own design for a twelve-unit apartment complex would have to be the marquee new build project for Americhanvre. This is a first for the U.S. hempcrete building scene as essentially the first commercial residential hempcrete project – which further adds proof of concept and viability for the material in commercial construction with modern, high-performance, off-site construction techniques. 

Conversely, our most notable retrofit project would have to be the Project PA Hemp Home installation for the DON group of companies in New Castle, PA. This project was funded in part by the PA Department of Agriculture as an examination into the viability of hemp as a new commodity for PA farmers and also as an examination of the performance of the material for low-income, state-subsidized, affordable housing and whether or not it has the ability to create homes that are, in fact, more affordable to own and operate. 

Project PA Hemp Home was the first residential home that we insulated with the Ereasy system and was studied by the Pennsylvania Housing Research Center (PHRC) at Penn State University – we will be working with PHRC and Dr. Memari to re-create that performance evaluation study on six more completed Ereasy insulated projects around the country with the funding provided by this U.S. Army award. 

Dr. Memari and his team documented a 30-70% reduction in heating and cooling costs as well as stable interior humidity levels of 55-60% on Project PA Hemp Home. We need more data to support these findings and expect these reports to also be cited in our effort to obtain commercial code compliance for the category.

HT: Talk about the Ereasy system from beginning to end. What are the key aspects of the technology and the building process that make it all work?

CM:  The most critical aspect of the Ereasy system in comparison to other spray-applied hempcrete systems on the market in Europe is that the materials are pre-mixed and introduced to the system wet, as opposed to combining at the end of the lance. This offers a few key advantages over the other existing systems, mostly related to the consistency of the mix ratio and the placement density.  It also allows for the rebound (any material that blows around and doesn’t stick) and excess material scraped off the wall in the leveling process to be re-incorporated directly into the mix.  

The pre-mixed hempcrete mixture is drawn through the system to the lance, pneumatically, via a 375cfm air compressor, making it the fastest, most consistent and least complex system for spray application of hempcrete. This is evidenced in our finished work upon visual inspection of the completed structure where it is impossible to identify starting/stopping points and variations in the mixture ratio.  

Although the binder for the Ereasy system is proprietary, it is the most lite-weight binder to hurd ratio on the market and ultimately the most cost-efficient – other spray systems can work with multiple binders, yet they consume dramatically more binder and are overall less efficient. Ereasy spray applied hempcrete also tends to cure more quickly, further condensing project sequencing times. 

When I first began to investigate spray application systems in 2019, my initial reaction was that they seemed to be messy and inconsistent, however the Ereasy system seemed to have been designed to address those issues and to provide a suitable solution for spray application of hempcrete.

HT: You’ve said you run a lean operation. When it comes time to jump into a project, where do you source the labor and how do you manage that work?

CM: Many of our projects have been completed with labor provided to me by the homeowner, general contractor or by colleagues of mine in the space. The way we have adapted the Ereasy system to be used in the U.S. makes it so that I have been very successful at quickly training a team of three workers to support me in running the equipment for a successful install. 

With the exception of the lance operation (typically my job), all three of the other jobs required to run the machine require little to no operator experience.  So, because we are using factory-weighed bags of hurd and lime in a one bag-to-bag ratio, a large capacity hydraulic mortar mixer with a water distribution bar and metering system, and because the other two jobs beyond mixing and spraying are as simple as raking and shoveling – we have trained well over 100 individuals on various projects to support me in running the equipment. 

It took time and input from all of the people who have helped to run the machines – many of whom are seasoned professional laborers – to optimize the worksite and equipment package, but we really have made it as simple as possible to run this equipment with a crew of just four people. Also, we have worked closely with colleagues in the space to join together and execute projects – perhaps none more than our colleagues from Massachusetts, Hempstone – and have been able to build a network of reliable subcontractors and colleagues who are capable of supporting us on projects. 

All businesses in the industrial hemp industry need to be athletic to survive, and by keeping our own overhead costs related to labor low, we have been able to pass those savings on to our clients who are already facing increased upfront costs when specifying the material.

HT: Is spraying hempcrete the most efficient way to apply the material? Can you talk about the economics of Ereasy, say, compared to form infill method? Preformed blocks, bricks or wall units?

CM: We have examined our own data from spray application installations versus cast-in-place projects and have found that, despite what seems to be higher material costs up-front (they are not, in reality), the Ereasy system represents a 20-30% reduction in overall costs versus traditional hand casting on site. This is primarily due to the speed of the installation and the overall reduction of person-hours on site.  For example, a 2,700sq ft timber framed home with a forty-foot gable was able to be sprayed by a team of four persons in about eight days, whereas this same installation would have taken anywhere from 4-6 weeks with a crew of five or more to complete by hand. 

Comparing the spray application system to pre-cast elements is a bit more difficult, but you have to remember that even a block or panel still requires labor to create and, more importantly, time in storage to cure before installation. We have explored the Ereasy system in combination with both pre-cast block and panelized systems and have found that the methods are complementary.  Whether the system is used to spray apply pre-framed panels in a controlled environment, or on-site in combination with hempcrete blocks, it really does help to condense project sequence times and reduce overall labor and costs. 

Now, where I believe the spray application has excelled in the U.S. construction market is in its adaptability to various wall construction details and its compatibility with American construction techniques. Spray application of hempcrete on-site really does interface more effectively with our current construction techniques and methodologies, and we have pursued opportunities to demonstrate and expand upon that flexibility with multiple combinations of techniques and on a variety of wall details for both new construction and retrofit.

HT: What is your advice to somebody who wants to get into the hemp construction business?

CM: First and foremost – pocket your reverence for the plant (I know, hemp can save the world…) when discussing the material with professionals in the construction industry. One of the most painful aspects of marketing hempcrete has been finding ways to overcome the “cannabis stigma” associated with fiber industrial hemp.  

Developers, architects, engineers and code enforcement officials will write you and everything you say off entirely as soon as they sense blind reverence for the material just because it is hemp.  

Focus your business and your entire mindset around the performance characteristics of the material and make it clear that, although it happens to be made of hemp, this material has dynamic thermal, fire resistance and material health properties that make it incredibly attractive from a performance aspect.  

Also, focus on solutions that fit the local construction vernacular in a given area.  The Ereasy spray-applied hempcrete system can be installed on a variety of framing and wall construction details that are common, codified techniques in the United States where the majority of new home constructions are site-built.  That said, keep an eye on cutting-edge construction techniques in development such as modular and panelized off-site construction systems.  Focusing on integrating your work with what is currently happening in construction will be an easier path to commercialization and revenue (think Hempwool Batts from Hempitecture and how easy it is to hand those to a contractor) while also keeping an eye on emerging techniques that will allow your products to evolve along with the construction industry in the near future.  

Support, join and participate in industry-specific organizations like the International Hemp Building Association (IHBA), the US Hemp Building Association in the U.S., or the Construire en Chanvre in France. We can go much further together than alone at this point in the industry, and in that same spirit, join forces with colleagues in the industry to exchange information, ideas and resources.  

If we are successful in raising awareness of, and interest in, hemp building materials, then there will be years of sustainable growth in the industry ahead of us.  If we are clandestine about what we are doing, over-protective of opportunities and unwilling to collaborate, then I fear we will struggle as a community to establish hemp-based building materials like hempcrete in the larger construction industry with legitimacy.  

Finally, what are you waiting for?!

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