Shell
sub-base

Composition

Whole residual shells from North Sea and Zeeland fishing (the Netherlands + Belgium) · recovered marine waste. No additives, no chemical treatment.

Made in

Belgium

Ecoschelp shells in the chute of the blowing machine, with the whole shells clearly visible

Whole shells, 15-35mm · a draining, insulating sub-base that breaks capillary rise, for crawl spaces, under screeds or perimeter drainage. 100% biobased, additive-free, reusable.

The material

What is a shell sub-base?

The draining shell sub-base is a loose fill made of whole marine shells, recovered from fishing waste in the North Sea and Zeeland. The shells act both as a drainage layer, thanks to their non-compacting shape, and as a capillary break, thanks to their inert, non-hygroscopic nature.

The air trapped between the shells adds thermal insulation value. The material holds up over time without degrading in contact with water, which keeps the fill durable even at the bottom of an excavation exposed to wetting and drying cycles.

It is intended for the base of crawl spaces, under screeds, for perimeter drainage around the building and for the base of a garden soakaway.

Ecoverbo, in Antwerp, collects the shells in Belgium and the Netherlands and delivers the material loose. At end of life, the fill can be removed and redeployed, or return to a natural marine cycle.

Installation

Installation & uses

The shells are tipped directly into the excavation, by hand on small areas or by mechanical blowing on larger sites. The layer settles naturally under its own weight, with no tamping or binder.

A geotextile layer can be laid at the interface with the natural ground to keep the fill clean over time. No anchoring or fixing is otherwise required.

The thickness determines the performance achieved: thinner for a capillary break alone, thicker to add insulation value.

At end of life, the shells can be recovered and redeployed on another site, or composted with mineral waste.

Perimeter drainage, shells in place at the foot of a brick wall showing their true texture, grading and colour — Perimeter drainage.

Shells blown by hose into a crawl space, masked operator at work — Shells blown by hose into a crawl space.

Levelling the shell sub-base with a straightedge in a basement.

About the producer

Ecoverbo is a Belgian producer of shell-based materials, based in Antwerp, specialising in recovering shells from North Sea and Zeeland fishing. The company offers two complementary ranges: Isoschelp, whole shells for draining sub-bases and insulation, and Ecoschelp, crushed shells for other uses.

The producer works with local fishing supply chains and delivers in Belgium and the Netherlands, on a short-supply-chain basis.

See the technical data

Layer of shells spread and levelled over the whole floor of a basement.

Technical performance

Conductivity λ

0.106W/m·K

Density

600-650 kg/m³

Strength

N > 20,000 kPa · failure value 61-88

Dimensions

Grading 15-35mm (whole shells)

FAQ

Is the shell sub-base loadbearing?

No. The fill is non-structural: it is tipped into the bottom of the excavation and settles under its own weight. Its crushing resistance exceeds 20,000 kPa, with a failure value of 61 to 88 measured at TU Delft.

Which thickness should I choose?

The thickness determines the performance achieved: thinner for a capillary break alone, thicker to add insulation value. The conductivity measured at TU Delft is 0.106 W/m·K.

Is a geotextile needed under the sub-base?

It is not compulsory, but a geotextile layer can be laid at the interface with the natural ground to keep the fill clean over time. The material itself does not degrade in contact with water, even at the bottom of an excavation subject to wetting and drying cycles.