Hemp Blocks


The hemp block is a natural insulation and building material produced in Belgium. The blocks are composed of hemp shives and a mixture of air lime and hydraulic lime. After pressing, the blocks are dried exclusively by outside air, in other words, no additional energy is required for this. Moreover, producing one hectare of hemp saves four tonnes of CO2 annually! The blocks are very versatile as wall insulation for both new buildings and renovations.
The hemp blocks can also be easily recycled by grinding them and pressing them into new blocks or using them as filling.

Raw Materials

The blocks are composed of hemp shives (at least 80% by volume) and a mixture of air lime and hydraulic lime. Both hemp and lime are imported from northern France, always within a maximum 250 km radius of the Fernelmont production facility.

The production process

  • Hemp straw is separated into fibers and shives during a processing process. For the hemp blocks, we only need the hemp shives, which we import from northern France.
  • When these arrive at our production facility in Fernelmont, near Namur, they are mixed with a mix of hydraulic and air lime and water following a precise recipe.
  • This mixture is then compressed in special moulds into hemp blocks of different thicknesses (7 to 36 cm) and different shapes (including blocks for our construction system)
  • The compressed blocks are then placed via an automated process in a ventilated room for 8 to 12 hours where they are left to harden.
  • Once hardened, they are placed on pallets by a robotic arm, which takes the hemp blocks outside where they have to dry for another 12 weeks. During this period, the lime carbonation process takes place where the lime starts to harden into limestone by absorbing CO2 from the atmosphere.
  • Cuttings or unused blocks blocks can be ground up and simply added back to the production process at step 3.

Thanks to hemp blocks, you can save up to 70% on your energy bill.


Hemp blocks are extremely versatile in all kinds of new construction and renovation projects. For example, they can be used for building houses thanks to the Hempro system, for interior and exterior renovations, interior walls and partitions, floor and roof insulation, extensions, and so on. You can find an overview of our projects here: https://www.isohemp.com/en/our-referencesThe facing brick was custom made for DING, the new wing of Design Museum Gent, to be built in 2023-2025.

Environmental impact

  • Short description (max 100 words) of the impact of this product and production process on the environment. Such as CO2 emissions, but also storage, degree of compostability, use of toxic substances etcetera. 
  • Hemp blocks are a 100% natural product (no use of toxic substances) that has a negative carbon footprint. Hemp blocks store up to 75 kg of CO2 per m3! This is mainly thanks to the hemp plants, which absorb 4 times more CO2 than trees. But also the very energy-efficient production process, where the blocks never have to be heated, ensures that the hemp blocks have a positive impact on the environment.
  • The hemp blocks can easily be recycled by grinding them and using them as hemp granulate to fill walls or simply by re-using the mixture in the production process.

Also nice!

  • They regulate temperature thanks to their ability to disperse accumulated heat. They form a real thermal buffer: the indoor temperature is kept constant and the impact of temperature variations between day and night is significantly reduced.
  • They regulate humidity thanks to their high permeability to water vapour. They play the role of humidity buffer, thus providing a constant and healthy climate for the building’s occupants.
  • They dampen and absorb sound. These “sound traps” dampen or absorb most of the sound waves and thus protect you from acoustic pollution.
  • They are non-flammable and do not emit toxic smoke. With their excellent fire resistance, they resist fire for up to more than 2 hours, depending on the finish and thickness.
  • This 100% natural solution also has a positive carbon balance; one m3 of hemp blocks stores 75 kg of CO2 (biogenic carbon).

Growth Opportunities

Where are the growth opportunities for this product? What is the need to be able to scale up? Where are the pain points at the moment? 

Hemp blocks have largely been saved from the extreme price increases faced by other building materials. This has made them a lot more affordable and in many cases even cheaper than ‘conventional’ building materials.

So it is mainly a matter of changing the awareness of the general public and the rigid, very traditional construction industry. Especially the latter is a big challenge, as architects and contractors who have been working with the same, often polluting, materials all their careers tend to cling to their old habits frenetically.

The benefits of hemp blocks on home comfort are well known, they are widely available, they are affordable and they have a positive impact on the environment. Once this message becomes known, the rest will follow.

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