Today’s post is from The House Made of Hemp article at Ecogizmo. You can read the full article for free on their site. I’m posting this because I see no reason why hempcrete couldn’t be used in earthbags. This would eliminate the form work and require less tamping than building with soil-filled bags. This would require more material, however, and an inexpensive source of fill material. One possible solution is vetiver grass. You could replace hemp with vetiver, and under certain conditions replace lime with clay soil. Considering the amazing benefits, some of which are listed below, I hope some fellow earthbaggers test this out and report their findings.
“America’s first house made primarily of hemp has been built. Using a product known as Hemcrete – a mix of industrial hemp, lime and water – a team of 40 volunteers, sub-contractors and designers have recently completed construction of a hemp house located in Ashville, North Carolina. [Note: Hemcrete is one brand of hempcrete.] Eco-friendly design and construction company Push Design has gained the support of community members and local officials alike and now plans to build more.”
“We recognized almost immediately that hemp was, in every way but in cost, seemingly the most effective and sustainable material available worldwide. The qualities it offers are beyond anything we get from typical materials, combining energy efficiency found in mass-based construction with the carbon sequestration, rapid renewability, strength, several hundred year wall lifespan, and the breathability and indoor air quality that is unsurpassed. It is an incredible combination, and a list of positive attributes we have never seen in any other material.”
“Hempcrete has some interesting qualities one of which is its ability to pull carbon from the atmosphere both while being grown and while in-situ producing a double edged sword for fighting climate change. Firstly at the cropping stage the hemp plants naturally use carbon dioxide for growth at about 22 tonnes per hectare, however the interesting factor is that the building itself continues to sequestrates carbon as lime in the hempcrete calcifies over time.”
“The fact that the lime content is constantly calcifying, turning to stone essentially, over the wall’s life span, means the wall is actually getting harder and stronger as time goes on,” Mosrie said. “The durability is unlike anything we have seen, with the exception of stone, as perhaps even beyond that as there is no mortar joint failure possible. Studies in Europe have estimated about a 600-800 year life span for the wall system.”
Note: A new book on hempcrete just came out – Building with Hemp, by Steve Allin. It’s available direct from his website.
Want to learn more? Here’s a good hempcrete video that claims it is stronger than concrete. YouTube also has a number of other good videos on the subject.
7 thoughts on “Hempcrete as Earthbag Fill”
We would love to do an earthbag home and the materials you suggest sound possible.
What stops us from doing an earthbag house is the plastic bags. They are not natural. Also, you’re surrounding yourself with plastic, which from an ancient Vedic construction perspective is not the best way to live. Plastic interferes with the aura and the energy of the human body, even if it is ‘sealed.’
Why are people not building earthbag homes with hemp bags or bamboo bags? Will these bags fail? Is there an alternative to the plastic non-environmentally friendly bags?
Yes, I agree that more natural bag material would be better in many regards; unfortunately the alternatives are not as strong and do not stand up to repeated moisture exposure as woven polypropylene do. In some cases it is possible to use burlap or even cotton bags where the fill is inherently stable and the bag strength is not so important. Of course, it is also possible to create earthen walls without bags at all, as with cob, adobe or rammed earth.
Could you add hemp Hurd to the soil to get the insulation properties without making Hempcrete
Adding insulation materials to thermal mass materials rarely yields a fill material with superior qualities; it usually degrades both in terms of inherent thermal properties.
I see a reason not to – HempCrete cannot support its own weight! Better off using sand-silt-clay-straw in the bags and plasting hempcrete on the inside and out, and maybe in narrow non-structural channels from the inside to the outside to allow the thing to breath like a hempcrete structure should.
Yes, but realize people are building lots of different types of earthbag buildings in lots of different climates for different purposes. This includes post and beam supported earthbags. It’s good to have options even though it may not be optimal for typical earthbag. In general, it seems like extra work and would not be practical for most projects.