Hempcrete Workshops & Resources

Resources for Hemp Builders

US Hemp Building Association

The US Hemp Building Association is the first professional organization for hempcrete builders. It is aimed at achieving full certification of hemp based building materials, including the hemp lime, or hempcrete, building system. Many of our key distribution partners - including the well respected Cameron McIntosh of Americhanvre Cast Hemp- are founding members and are featured as USHBA board members.

Building With Hemp & Clay

Some of the most ancient building techniques utilized just hemp fiber stalks and clay. Today, builders have the historically unique ability to make a modern hempcrete recipe utilizing just raw hemp hurds and hydrated clay. We live in an exciting time, with an unprecedented access to high volumes of pure hemp hurds, and the technology required to produce them (proper mechanical decortication which cleanly separates bast fibers from hemp hurd / core; the greatest technological breakthrough of the past three hundred years). The implication of this high performance material has only just barely begun to be understood. No field has been more dramatically and immediately impacted as the construction industry. While Hemp Lime has been the preferred building material- due to its relative ease of drying- high quality hemp hurds allow an easier means to use cheap clays to build high performance structures.

Building with Hemp & Clay Challenges & Solutions

While cheaper and more natural than the Hemp Lime method, the Hemp Clay method is more difficult to dry properly after casting. While we always advocate using a high quality hemp hurd when building with hemp- regardless of your binder choice- it is especially important to select your hurd carefully when building with hydrated clay binder, as there is a greater risk of rot and mold. Use Chanvra Core or another CenC certified hemp hurd to ensure your hemp has optimal moisture content and low colony forming units, and be sure to monitor the wall carefully.

Learn more about our Chanvra Core hemp hurds and our high standard of Quality by clicking here.

How to Build With Hemp & Clay

Start by locating soil with a high clay content that can be ethically harvested. Avoid harvesting from virgin ecosystems in a way that causes damage- try to provide an ecological service with your clay harvest. Maybe there is a construction site nearby that needs to dispose of some clay fill. Better yet, try digging a pond for a permaculture project!

There are many videos and articles available on the internet about how to use a simple jar test to estimate clay levels in soils. Once you've located a good clay source, soak it overnight in barrels. Then, mix it up with a painters bit to produce a light, hydratec clay slip. Make sure the clay is not too heavy; you want a nice, light consistency like melted chocolate.

Mix the hydrated clay with high quality hemp hurds, using the same method you would use to mix hemp and hydrated lime. We recommend a vertical pan mixer. Or better yet, have your friends over and have a hemp mixing party! Unlike lime, clay is great for your skin, and mixing with your feet and hands is a rewarding experience!

Pack the Hemp Clay mix into your form system. Use the same best practices for formwork that you would use for Hemp Lime construction. Avoid over tamping. Hemp Clay requires even less tamping than Hemp Lime. Just a light tamp along the formwork will do. Leave the material in the middle of the form completely untamped.