how to make hemp concrete

How to make small scale hempcrete? Answered

It is supposed to be just made of lime, shredded hemp stalk (which you can replace with straw if not available) and water. There is also briefly mentioned a lime heating process, but nothing more detailed than that.

I’m not into making a house with this, but I would be interested in making things like plant pots, small tables and stools, and various artwork with it.

I need more info though. Like.
Is there a specific kind, or prepared lime I need to use?
What is this heating process you need to do to it?
What parts lime to hemp/straw is recommended?
How long is the curing process?

It seems like you could make some neat things out of this, but I haven’t found anyone doing so. Are there any experts that could offer advice about this kind of thing?


There are several variations of this mix possible, as Kiteman pointed out using ready to go concrete is the easiest way.

But in other areas of the worls just water is used, when it freezes the added fibres even make the stuff shatter and bullet proof.

A friend of my in Europe had experimented with alterative building materials for many years, so I will try to list what I still remember from his work:
You can use all sorts of “filling material” from dried grass, over long straw to tyres and polysterene foam bubbles.

Polystyrene makes a very light weight concrete with uperior insulation properties.

Compared to a normal block of concrete you can save up to 40% weight.

Instead of concrete old mixtures based on hydrated lime, clay or even mud can be used, he experimented at one stage even with resin from pine trees as a binding material.

The key to success is preperation, the ingredients must be dry (no moist plant material) and fibres should not be longer than 15cm unless you are using moulds where you can compress the concrete properly before it sets.

If the fibres are too long you will have the problem that they lump together causing a mix concrete with a massive ball of (censored) floating in it.

Modern technology is really good and a concrete mixer would be the obvious choice for the mixing job, but my friend actually prefers a big tarp on the ground plus a concrete mixer.

Concrete and sand (or clay, mud) are prepared in the mixer, the filling material is spread over the tarp.

Add the ready concrete ( a bit wetter than what you would normally use for making concrete jobs) and spread it over the filling material.

Now you work the mix with 2 or more people by lifting the tarp on the sides and edges, literally rolling the mix from one place to the other.

The mix is ready when it is evenly mixed and the concrete gets back to a normal consistency – at this stage the plant material has partially absorbed the water from the concrete causing a really good bond after curing.

You can check the quality of the mix by breaking it with a hammer, it should not seperate around the fibres but with them.

Key for outdoor use is to make it waterproof, so the foundations should be normal standard concrete and the outside surfaces should be painted or covered with some rendering material.

If the natural look should be kept get waterproofing additives to mix directly into the concrete and seal the outside with lisnseed oil or similar – be aware that natural coatings need to be re-applied every few years or when there is the need for it, like on the weather side of a wall.

I was watching this video about hempcrete. It is supposed to be just made of lime, shredded hemp stalk (which you can replace with straw if not available) and water. There is also briefly mentioned a …

Learn how to make your own hempcrete

Hemp is a great natural material that is incredibly versatile and that has numerous uses, including construction.

It’s becoming so popular that composites like hempcrete are taking precedence over concrete.

But first let us explain a few things…

What is hempcrete?

Hempcrete is a biocomposite material that is becoming more and more popular for use in construction. It also goes by many other names such as Canobiote and Canosmose.

While it might seem like a recent development, hempcrete insulation has been used since the 1990’s in France. In our current ecological situation moves towards sustainable alternatives like hempcrete are increasingly welcome.

What are the benefits of hempcrete?

Hempcrete products, like hemp blocks, may provide assistance to areas that are traditionally technically challenging.

Hempcrete itself provides many advantages including:

  • Thermal regulations
  • Humidity regulations
  • Fire resistance
  • Acoustic insulation
  • 100% natural

Thermal Regulation

Hemp blocks or hempcrete bricks are natural temperature regulators due to their ability to diffuse accumulated heat efficiently. This in turn allows the blocks to contain heat in winter and naturally distribute the heat in summer to avoid overheating.

Humidity Regulation

Hemp is incredibly effective at maintaining a healthy indoor climate. In homes built with hempcrete you can guarantee a constantly healthy climate for occupants. This can be especially effective in areas where humidity is usually high.

It can also be effective for renovation of old buildings suffering from dampness and can prevent any future condensation issues. A surefire way to conserve the state of the building.

Fire resistance

This is largely dependent on the finish and thickness of the hempcrete used. But hempcrete and hemp blocks can offer up to two hours of fire resistance.

Acoustic insulation

Hemp works as a fantastic insulator of sound. It can trap and dampen sound waves, protecting you from noise pollution far easier. Blast your music as loud as you like, too!

UK Hempcrete

Alex Sparrow, director of UK Hempcrete discussed with The Extract how to make hempcrete and its many benefits for the environment. It’s easier than you think to craft bricks out of hemp. Indeed, ‘hempcrete’ is becoming a big thing in the world of DIY.

How to make a hempcrete wall

Constructing a hempcrete wall is actually a lot simpler than might be thought.

The three ingredients are hemp hurd, lime, and water.

Use four parts hemp hurd with one part lime binder and then one part water. Added all together they form an incredibly durable material.

It’s also easy to make and can be made in almost any shape. The end result is something that is similar to a pressboard, and far stronger than it feels.

Hemp hurds are easy to come by and make up the bulk of the recipe. Just mix the hempcrete into the form, tamp it down, and let it set into a solid block.

Why use hempcrete?

Hempcrete is resistant to cracking and acts as a good moisture regulator and an insulator. It is ideal for use in earthquake-prone areas. It lacks the compressive strength of the kind of concrete that is used in residential construction, but it is strong enough for small buildings, and very durable. It’s ideal for fences, walls, small homes, sheds, etc.

Even better, hempcrete can be broken down once the building reaches the end of its useful life, so if you’re expanding/changing or renovating you can break the hempcrete down and recycle it or use it as a soil amendment. Harvest more hemp, make more bricks, and the cycle continues.

A versatile and eco-friendly construction material

Hempcrete puts the power back in the community’s hands. It is easy to grow, affordable and environmentally friendly. It’s rare you will find something so powerful and versatile that is so easy to make. A community can build a home in a short space of time using sustainable materials such as locally grown wood and hand-cast hempcrete bricks. The slowest part is waiting for them to set.

It’s becoming so popular that composites like hempcrete are taking precedence over concrete.