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Skellet as load bearing system

Modular steel construction system

Skellet as load bearing system


Left: detail of a Skellet joint. Right: 2 modules.

1. Round tubes are structural the most efficient, but hard to connect.
2. Square profiles with second best structural properties are better, but the downside is that the thickening of the connectors gets in the way.
3. The cross-box Skellet profile combines the strenght of the square tube with space for all kinds of connecting pieces.

3rd reassembly of a Skellet system in GTB Lab Module


The load bearing system of GTB Lab Module makes use of Skellet. The system can be dismantled down to the smallest component. Both the profiles and the connectors can then be reused in any project. The reusability also means that the profiles and connectors retain a higher residual value.


Skellet is a construction system that can be used in a variety of applications. The system consists of two steel profiles and a range of connectors. The Skellet profile is a cross-box steel profile with recessed surfaces in which holes are punched every 25 mm. These holes create a grid that ensures a stable construction. Each connector is designed with the same holes and can therefore always be connected to the grid, which makes building with Skellet very accessible to any (do-it-yourself) builder. This hole pattern ensures dimensional consistency and flexibility, a key requirement for circular design.

The Skellet construction system consists only of bolted and riveted joints. These can be loosened without damaging the profile or the connectors. These profiles can then be perfectly reused in another project.


4D Architects



Manufacturing location

Kompellaan 11, Genk, Belgium


Steel cold-rolled




Height (or depth):


4 800 mm

2 400 mm

3 6250 mm

2 mm


Cross box, perforated every 25 mm

Surface damage


Hazardous materials


Material history

2019 - produced and assembled in Ridderkerk NL
2021 - reused in GTB Lab, Heerlen NL

Circularity data

Reversible BIM: the 3D color-coded model visualizes the reuse potential per element.
RP Product legend.png

Reversible BIM: the 3D color-coded model visualizes the reuse potential per element.

Reuse Potential:

Recovery option


Direct reuse

Embodied mass:

Embodied carbon:

5,29 ton

8,20 ton CO2

No. of elements:

No. of relations:

No. of disassembly steps:

No. of standardized relations:




Avoided waste:

Avoided carbon:

3,47 ton

5,38 ton CO2

Skellet as load bearing system


Remaining Technical Life Cycle:

96 year

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