The First Permitted Hempcrete Structure in Denver

Left Hand Hemp knows there is a better way to build. Through hempcrete building workshops, we teach how to work with the hemp as a construction material. For this project. community members, students, hemp industry professionals and interested construction groups came together to help build an architecturally rendered, CO2 sequestering and fire-resistant building from “Hempcrete”.

Hempcrete consists of hemp hurd, lime and water.

Here is a quick peak at the timeline:

First, Architect Bob Escher, with Escher Designs in Vermont, and Homeowner Eric McKee came up with the design for the 16 x 20 workshop building.

Next, McKee talked to the city building code office about the properties and benefits of hempcrete and got an approval to build a 16 x 20 workshop space! A concrete pad was laid and in three weeks, we would were ready to begin putting up the structure!

The General Contractor, Timberwight, and Builder, Mark Cover from Forbes Road Sawmill put together the post and beam structure with wood from McKee’s family land in Pennsylvania. Beautiful 8 inch thick hemlock beams were milled and shipped to Denver. With the help of Mark’s right hand man, Onefree Foster, and a crew of ruffians, the post and beam structure was up in just 2 and a half days!

Hempcrete has to be formed into the walls in a similar way that concrete is poured into forms. The main difference is the texture, where concrete is wet, hempcrete has the consistency of moist granola. Forming is always the slowest part of the process with hempcrete. We had an amazing group who were able to more than handle the task of moving, cutting, and attaching the forms as the hempcrete crew was always close behind. Ideally, a homeowner would want to construct a monolithic structure (hempcrete for the walls, the floors, and the ceilings of the building) as to eliminate thermal bridging to the outside.

The simple ratio of hemp hurd, lime and water is used in creating the hempcrete insulation material. In a mortar mixer (not concrete mixer) we mixed together Saint Astier’s Batichanvre, (Hydraulic Lime), from Transmineral, hemp hurd from Ole Dominion Hemp, and water.

We had teams mixing and packing in the forms. The mixing team tested each batch to ensure we reached our desired consistency. Once the batch was ready (about 10 minutes in mixer) it was transported to the building where the ready team of hempsters was anxiously waiting to put it into the forms. When installing the hempcrete, it is best to “hand tamp” with enough pressure to compact it, but not too much as you could diminish the pore space between the hurd pieces. Overtamping with tools and too much force can lessen the R value by reducing the amount of air that is able to be trapped in the material.

Hempcrete replaces fiberglass, drywall, and latex paint.

A natural earthen plaster is the best exterior and interior treatments for hempcrete.

Hempcrete packed in wall form.
The crew packing the hempcrete mix into the first wall!
This brand new mortar mixer worked perfectly with the light hempcrete blend.

2 thoughts on “The First Permitted Hempcrete Structure in Denver

  1. I am curious as to the what cost of the hemp material per cubic yard would be. If you can inform me of this cost I would appreciate it. I really like the idea of green building. It also looks like a fairly woody product yet you state the chemistry bonds with portland (lime).

    Thank you,

    1. An estimate is $6 pr cubic ft for hemp construction. Yes, the hemp hurd is a woody-type of material because the stalk is hardy and dense. Lime and water coat the hurd to protect it and help bind. Our first workshop is now available for registration, come construct a home with us and learn all about it! Thank you.

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