Insulated self-build block: what is the Gablok insulation?

What type of insulation is used in our self-build blocks? What is their insulating value?


Among all the insulators available, Gablok has made the choice of expanded polystyrene with graphite additive (EPS) for its building system.


Polystyrene and sustainable development

EPS is about 98 % air. The remaining 2 % is material derived from oil refining. EPS gives a second life to this material that could not have been used as a fuel.

The basic product has the form of styrene beads. The beads increase their volume by 40 times their size into contact with water vapour without solvents or other adhesives.

Contrary to what you may think, styrene monomer is a component that is naturally found in plants. It is not bad for health, it remains stable over time, it has no negative impact on the environment and it is neither toxic nor polluting.

In everyday life, we find EPS in some food packaging because it does not cause any allergies or illnesses.


Carbon impact and ecological footprint of the insulated formwork blocks

EPS is environmentally friendly. It also has the great advantage of being a high-performance insulation system.

The carbon footprint of a traditional house or timber frame insulated with EPS will be superior to that of a masonry construction.

EPS requires less transport given its small size and takes up less space.

Because of its expanding capacity, it does not use considerable amounts of water and energy to increase its shape. The company X-PACK conducts the expansion work in Verviers, than moulds the EPS into the insulating blocks we use.

EPS is a recycled and recyclable product.


An alloy of wood and EPS is manufactured for impressive performance.

The EPS insulation designed for Gablok insulated wooden blocks is combined with OSB formwork.

The blending of wood and EPS allows Gablok constructions to benefit from a very interesting insulating value and energy performance.

The thermal conductivity (“U” value) of a wall built in Gablok is 0.15 w/m²k. Our insulated wooden blocks will be able to meet the 2021 EPB requirements.

The thermal conductivity value (“λ” value) of the EPS is R=0.035w/mK.

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