IsoHemp hemp blocks
At Lehm-Laden you will find everything that makes building with natural building materials easier and more attractive – including the hempcrete blocks from IsoHemp!
These innovative blocks made from hemp and lime offer a solution for insulation, a balanced indoor climate and building with materials made from hemp and lime.
What is IsoHemp hemp block?
IsoHemp manufactures hemp and lime products for the construction and renovation sector. The company offers its customers solutions for the efficient insulation of building envelopes for all new-build and renovation projects, whether residential, commercial or industrial buildings. The plant in Belgium, in the province of Namur, produces more than two million hemp blocks every year and constantly keeps 4,000 pallets in stock.
The aim is to provide maximum comfort and wellbeing in your home while helping to reduce energy costs. Their hemp blocks consist solely of hemp shiv (the woody part of the hemp plant) and lime. Together, these materials produce a lightweight, vapour-permeable block with excellent insulating properties.
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The advantages at a glanceThe advantages at a glance
Excellent thermal insulation
With a thermal conductivity of 0.071 W/mK, the blocks provide excellent thermal regulation.
Moisture
regulation
The hemp blocks can absorb moisture and release it again, thus contributing to a balanced indoor climate.
Sound insulation
With a sound reduction index of up to 44 dB, the blocks provide effective sound insulation.
Fire protection
The hemp blocks achieve the reaction-to-fire classification B-s1,d0 in accordance with EN 13501-1 and a fire resistance of up to EI 240 (at 36 cm with plaster).
Raw materials
The blocks are made from hemp and lime.
Interior insulation: why the insulation value alone is not enough
With interior insulation, people usually only look at the λ-value. For a pleasant indoor climate in summer, however, it also matters how much mass on the room side can absorb heat.
An old solid wall buffers heat well as long as it is connected to the room. If a lightweight insulation board is glued on the inside, the heavy wall is decoupled from the room – the room heats up faster. A lining wall of hemp-lime blocks insulates and at the same time brings the mass to the room side.
| At the same insulation value (R ≈ 1.7 m²K/W) | Hemp-lime block + HL-Mix | Lightweight mineral insulation board (mineral foam, approx. 90 kg/m³, glued) |
|---|---|---|
| Mass on the room side | approx. 38 kg/m² (12 cm) | approx. 7 kg/m² (7–8 cm) |
| Phase shift (ISO 13786) | 7.9 h at 12 cm, 13.1 h at 20 cm | – |
| Uneven existing wall | levelled out in the HL-Mix backfill | levelling plaster needed, then drying time |
| Surface | solid plaster base | reinforcement layer with mesh needed |
| Shelves, kitchen, TV | fixing in the block wall (HempFix, loads as per test report) | special plugs for light loads, heavy loads through the board into the wall |
| Thermal conductivity λ | 0.071 W/(m·K) | approx. 0.042–0.045 W/(m·K) |
If you only look at the λ-value, the board allows a thinner build-up. If you want rooms to heat up more slowly in summer, you need mass on the room side – and at the same insulation value, the hemp-lime block brings more than five times as much.
Hemp-lime block data: IsoHemp catalogue 2026 (density approx. 320 kg/m³, R 1.69 m²K/W at 12 cm). Insulation board: typical manufacturer data for mineral interior insulation boards.
Hemp and lime – a combination that makes sense
The symbiosis of humanity's oldest cultivated plant, hemp, with one of the oldest and most proven building materials, lime, results in the building material of the future: hemp-lime block.
The hemp plant grows around 50 times faster than wood. On one hectare of hemp field, the biomass for a small detached house grows in just 5 months.
Combining loose hemp shiv with lime and minerals makes the material rock-hard and resistant to external influences, allowing the building to last for many generations. This reduces maintenance effort and saves costs.
The 36 cm hemp block achieves a thermal resistance of R = 5.07 m²K/W (λ = 0.071 W/mK, FDES). Hemp-lime can buffer fluctuations in indoor humidity.
CO₂ storage: around 62 kg per m² of wall (FDES)
Characteristic value according to EN 15804+A2: around 62 kg CO₂ per m² of wall stored in the hemp (biogenic carbon, according to FDES INIES No. 20251046948 for the 36 cm hemp block PAL36EX).
Over the entire life cycle (A–C), the FDES reports +58.9 kg CO₂e per m² of wall – the chart shows the individual stages.
IsoHemp takes back hemp block offcuts from the building site through its RecyHemp programme (collection points in Fernelmont and Ghent, Belgium) and processes them into new materials.
Incidentally, hemp shiv, which makes up most of the block, is a by-product of hemp fibre production.