Concerned about indoor air quality, Neil Decker and Stella Michaels wanted their home to be chemical-free, so they decided to build it out of hempcrete (hemp, lime, and sand).

The couple didn’t think they could afford to live in California but found a rundown property in Gold Rush old country on the Western Slope of Sierra Nevada just outside Nevada City (above 2500 feet, with cold winters), where they moved into a fifth wheel trailer while constructing their home.

They had experience building with earth-bags (flexible formed rammed earth) but felt it was too hard on the body. They knew hempcrete was lightweight and was easy to work with. They were able to raise half the house in 5 days.

They then trained and hired local students to help finish the exterior build just before the winter rains. They then let the house get wet and dry during the winter, which helps to harden the lime before adding a lime plaster to the exterior. The couple added clay plasters to the walls for the interior and laid an earthen cob floor.

The couple was told by locals that we wouldn’t be able to get hempcrete approved, but the local building department told them as long as they met the codes for insulation value and raking strength, there should be no problems. And in 2016, they were the first hempcrete home approved in California. Decker explains that not only is hempcrete extremely durable, but it’s also fire and earthquake-resistant and can help with indoor air quality since it’s very breathable and mold-reducing.

Decker had spent a lot of time in yurts as a ski guide, and he liked how it felt to live in a circular structure, so they decided to design a perfectly round home. They spent 2 years observing how energy flowed through our property to choose a building site.

Inspired by Earthship design, the home is passive solar with nearly all glass on the south, passive cooling with a 6-foot openable skylight controlled by a thermostat that allows heat to escape when indoor temperatures rise above 75 degrees.

Cooling tubes are buried 5ft underground and run 50 ft in front of the home to cool ambient air outside the house's interior. Cool air is passively pulled into the tubes as hot air escapes out of the skylight in the summer.

Neil & Stella's home is among California's first permitted hemp homes.

TIMELINE:

0:18 Moved to a more affordable area outside Nevada City (Sierra Nevada foothills) and built a 40-foot Hemp Roundhouse (1st hemp roundhouse in the US, among the first permitted hempcrete homes in CA).
4:27 Living on the property while building.
8:50 Using clay plaster and hemcrete in building a sustainable home.
13:40 Hempcrete specs as building material (a breathable wall system made of hemp, lime, and water used to restore traditional buildings and is now being used to build houses).
18:15 Earthen floor that provides grounding and natural healing.
22:01 They wanted a small, simple bedroom with soft lighting, and the whole place tries to inspire calm and natural beauty.
26:19 Neil Decker's background living in a roundhouse and the benefits of its design.
30:32 Home uses passive cooling systems to reduce utility bills.
34:50 They wanted a healthy home that would last multiple generations and were excited about their house's unique and special features.

Some people are suggesting in the comments that Nils affirmation about "grounding" of the human body with the Earth is some invention. The reality is more complex, and several scientific studies explore "Earthing" (or reconnection with our environment) by, for example, frequently going barefoot. Here's one article published in 2012 (from the National Library of Medicine): "Earthing: Health Implications of Reconnecting the Human Body to the Earth's Surface Electrons": https://www.ncbi.nlm.nih.gov/pmc/arti...

Abstract of the paper: "Environmental medicine generally addresses environmental factors with a negative impact on human health. However, emerging scientific research has revealed a surprisingly positive and overlooked environmental factor on health: direct physical contact with the vast supply of electrons on the surface of the Earth. Modern lifestyle separates humans from such contact. The research suggests that this disconnect may be a major contributor to physiological dysfunction and unwellness. Reconnection with the Earth's electrons has been found to promote intriguing physiological changes and subjective reports of well-being."

—Hempcrete Roundhome owners' personal website, Starseed Creative: https://www.starseedcreative.com/
—Check Neil Decker's video on the house project, "1st Hempcrete Round House in the USA"    • 1st Hempcrete Round House in the USA  
—Neil Decker's channel:    / @neildecker1  

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