100% HEMP



OTRA sprl offers different construction systems from hemp:
"HEMPRO, MOBHEMP - prefabrication in the workshop, Columns-Beams, CLT…"

Lime-hemp has exceptional qualities in terms of energy efficiency, feelings and indoor environment. This material is suitable for new, for renovation or for extensions.

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OTRA sprl has acquired the experience and unique know-how on the market with its many sites, which are thousands of square meters installed to date, both in new constructions, as in renovations of heritage and exceptional buildings, as well as than in the industrial and private sector.

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Thanks to this experience, OTRA sprl has become a real player in the hemp sector.

We can intervene on the Belgian market as well as on the European market.

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In energy renovation and sanitation systems, we have different systems that optimally perpetuate the building with hemp in combinations or not with other natural techniques.

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OTRA sprl also masters other natural techniques of construction, renovation and extension.

Sometimes the exterior facades cannot be changed because the aesthetic character of the house wants to be preserved or due to lack of space. Renovating your building from the inside is therefore an effective compromise between comfort, cost and an appropriate technical solution. Hemp blocks provide an effective and efficient solution in the management of technical challenges during a renovation by guaranteeing the preservation of the existing building.
OTRA rénovation intérieur
OTRA Isolation intérieur bâtiment industriel en blocs de chanvre avec enduit à la chaux. Réalisation OTRA/AD-mix sprl - www.otra-construct.com

Isolation intérieur bâtiment industriel en blocs de chanvre avec enduit à la chaux. Réalisation OTRA/AD-mix sprl 
1300m2 de blocs de chanvre

OTRA 600m2 de blocs de de chanvre de 12cm + remplissage de la coulisse 3 à 10cm. Réalisation OTRA/AD-mix sprl www.otra-construct.com

600m2 of 12cm hemp blocks + filling of the slide 3 to 10cm . Realization OTRA / AD-mix sprl

OTRA Isolation d'une orangerie

Insulation of an orangery

Realization OTRA / AD-mix sprl

OTRA 1200 m2 d'isolation intérieur d'un château en blocs de chanvre de 12 cm avec enduit au PCS, remplissage de coulisses de 2 à 8cm.  Réalisation OTRA/AD-mix sprl www.otra-construct.com

1600 m2 of interior insulation of a castle in 12 cm hemp blocks with PCS plaster, filling of slides from 2 to 8cm. 400m2 of cork for interior insulation
Realization OTRA / AD-mix sprl

Why is a lining from the inside of the building with hemp blocks recommended

  • Cut the walls from the cold by eliminating thermal bridges and possible condensation problems (dew points)

  • Moisture management at old material / new material interfaces

  • Take advantage of a straight support for the interior plaster
    (straighten out plumb walls)

  • Fix technical ducts

  • Provide good sound insulation

  • Keep thermal mass inside

  • Apply cabinets, sink and decorative items

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Why choose hemp blocks as a counter partition?

For humidity management

During a renovation, it is recommended to use breathable materials, resistant to condensation and not rejecting any volatile organic compound. The hemp blocks perpetuate the existing building and continuously regulate the humidity of the air thanks to a breathable wall permeable to water vapor. The block is placed in lining of the interior wall and allows, among other things, to insulate old brick / stone walls or damp walls. It is one of the only products that retains its insulating characteristics even in an environment with high humidity. The wooden floors are protected from condensation.

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Efficient thermal insulation

In winter as in summer, you seek to maintain a constant and pleasant temperature within your building. The hemp block meets this need by naturally regulating the temperature of your home thanks to its ability to diffuse the heat it has accumulated. Its great inertia protects against the cold in winter and heat in summer.

For their fire resistance

Non-flammable and fire resistant, hemp blocks provide fire resistance of 1 to 3 hours depending on the thickness of the block.

Significant sound insulation

Noise pollution is greatly reduced thanks to the specific properties of the product.

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An excellent phase shift

The phase shift is the time it takes the heat to pass through a material. The 30 cm hemp blocks have a 19 hour phase shift which is excellent! This will make it cooler in summer indoors and warmer in winter.

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A building material with high diffusivity

the diffusivity of the materials increases the comfort in terms of feeling which makes it possible to heat less for the same comfort, 1 ° less = to + -7% of energy not consumed! With the hemp block you can gain up to 21% additional energy thanks to the diffusivity effect.

OTRA Finition à la chaux, réalisation OTRA sprl : www.otra-construct.com

Interior finish with lime on 600m2 of 12cm hemp blocks + filling of the slide 3 to 10cm

OTRA Système Hempro d'Isohemp, construction poteaux-poutres béton avec blocs de chanvre
OTRA Système basse-énergie et passif de construction HEMPRO d'ISOHEMP, Poteaux-poutre béton avec remplissage de blocs de chanvre. Mise en route OTRA sprl : www.otra-construct.com

Start-up of an ISOHEMP HEMPRO construction site,
Concrete post-beam with 30 cm + 20 cm hemp blocks

Low carbon concrete post-beams *: perfect for low-energy constructions

Low carbon concrete * associated with the Hempro construction system constitutes a simple, ecological, fast, economical, personalized and efficient solution.

It meets your needs for modern homes with large openings. From single-family homes to buildings, including eco-districts, you can easily build
low energy , very low energy or passive .

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Hemp blocks and wooden constructions are the perfect combination
of a light construction with an insulating block providing great thermal inertia.

The advantages of timber construction

Building a wooden house guarantees a comfortable building and high energy efficiency. Some major advantages of a wooden construction:

  • speed of construction (no more than 2-3 weeks for the shell)

  • less risk of thermal bridges (wood more insulating than traditional masonry)

  • direct economic benefits (savings on foundations thanks to the low weight of the wood)

Lightweight wooden constructions therefore seem to be ideal for your project. However, they have a weakness: precisely because of their lightness, they are subject to significant temperature variations which seriously impact the control of consumption and the comfort of the inhabitant. It is therefore essential to combine lightweight construction with products with very good thermal inertia without losing the economic advantages of this type of project.

Oak structure for post-beam construction
with hemp block filling

OTRA - poteaux-poutres bois

Hemp blocks for wood post-beam construction

Used for industrial, office or residential projects, the wood post-beam system allows you to build large with reasonable budgets. Some projects combine concrete, wood and steel to benefit from the advantages of these different materials.

Fast construction with economic benefit

Opening up of living spaces

This constructive technique finds its meaning in modern and traditional housing projects offering non-partitioned common rooms with large openings to the outside.

OTRA Plan 3D de la maison type d' OTRA sprl Structure chêne pour construction en poteaux-poutres avec remplissage en blocs de chanvre

3D plan of the typical house of OTRA sprl
Oak post-beam structure for a very low-energy construction with filling in hemp blocks.
Exterior finish in Eco-brick chips and lime plaster.
Interior finish in single-layer clay

Your advantages :

  • large volumes of living rooms

  • large glass openings (preferably to the south)

  • optimization of the use and consumption of materials

Result: contemporary and traditional buildings, economical and very comfortable!

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Why use hemp blocks in wood post-beam structures?

  • envelope and filling of the entire structure

  • efficient insulation

  • interior or partition masonry

  • lining of heavy masonry or prefabricated wall

  • fire resistance

OTRA - enduit de chaux -immo golf

Oak structure Emac in Wood by Emac invests our partner

Advantages of hemp blocks for wood post-beam constructions

Complete impact resistant walls with unmatched thermal, acoustic and fire protection performance

A unique, simple, quick to install and efficient filling product solution

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A perfect combination with wooden, concrete or steel structures

A wide range of block thicknesses to fill any type of structure and adapt to the constraints of your site

The possibility of inserting the frames into the enclosure without having to recreate an intermediate frame.

OTRA Réalisation d'un immeuble à appartements CLT et blocs de chanvre 30CM : OTRA/AD-mix sprl

Construction of a CLT apartment building
and 700m2 30CM hemp blocks with lime finish
OTRA / AD-mix sprl

OTRA ossature bois et chaux-chanvre
OTRA - chaux-chanvre

Construction of a building with CLT apartments and 30CM hemp blocks

OTRA / AD-mix sprl

This constructive system of cross-laminated timber panels, often referred to as “solid panels”, is used in all kinds of construction projects, both residential and non-residential.

Fast and solid construction

The advantages of CLT constructions

  • High rigidity of the construction

  • Simple and quickly mastered constructive knots

  • Very fast assembly of the construction: in a few weeks, it is possible to complete the closed shell of the building.

Just like the realization of a wooden frame construction, the use of hemp blocks associated with a CLT structure is possible both for interior and exterior lining.

In addition to this, you need to know more about it.

Advantages of hemp blocks
for the CLT outer casing

  • Perfect and rapid airtightness of the building

  • High thermal inertia thus avoiding any potential overheating problem

  • Excellent support for exterior finishes (cladding, plaster, etc.)

Advantages of hemp blocks
for the inner CLT casing

  • Very significant improvement in thermal inertia, which allows heating energy to be stored and the heat of the interior walls to be conserved

  • Water regulation

  • Very little resonance thanks to high acoustic absorption

  • Wide choice of plasters and glued or fixed finishes

  • No vapor barrier required

  • Lightweight interior walls

For an optimal result, an interior and exterior lining is recommended.

Hemp blocks for timber frame constructions

Hemp blocks are the best assets for light frame projects, both in the exterior and / or interior envelope and in partitions. They combine the advantages of excellent thermal inertia, high performance acoustic insulation and great finishing possibilities.

Fire resistance and reduction of exterior noise

Advantages of hemp blocks for the outer casing:

  • Failure of thermal weaknesses of the framework

  • No overheating in summer and no temperature drop at night

  • Significantly reduced exterior noise

  • Practical support for finishes

Lime plaster for apartment building in CLT with 30 cm hemp block insulation: OTRA / AD-mix sprl

OTRA cloison chanvre

Concrete post-beam constructions, many advantages

  • Homogeneity of the wall

  • Custom construction: The Hempro system meets many technical challenges and allows all types of projects to be carried out.

  • Time saving on site: a single insulating material, large and light, therefore installed quickly. Interior and exterior finishes applied directly to the masonry

  • Large volume of living rooms and large windows

  • Simplicity of construction: frames inserted into the enclosure without having to recreate an intermediate frame

  • Healthy and natural product

Results of constructions in load-bearing structure: contemporary, economical and very comfortable buildings!

OTRA cloison chaux-chanvre
OTRA cloison chaux-chanvre
OTRA cloison chaux-chanvre
OTRA cloison chaux-chanvre
OTRA cloison chaux-chanvre
OTRA cloison chaux-chanvre

Construction of 500m2 partitions in 15cm hemp blocks with PCS plaster, open steamed lime plaster: realization OTRA / AD-mix sprl