How strong is natural stone composite? The test values explained

Stronger than structural steel — tensile strength 535 MPa, demonstrated by test report. That is the fixed wording Omnistair uses to describe the strength of the overlay tread profile. But what does such a figure actually mean? And why do we always mention a standard and a source, while many suppliers settle for "rock solid"? In this article we explain the test values — understandable for anyone renovating a staircase at home, and complete enough for anyone preparing a project file.

Three values, three types of load

A stair tread endures three types of forces, and each has its own test value. The tensile strength of 535 MPa describes how much pulling force the material can withstand before failing. The compressive strength of 752 MPa concerns the force that really matters on a staircase every day: the weight of footsteps, moving boxes and furniture carried upstairs. The flexural strength of 680 MPa indicates how much the profile can take before bending or breaking — relevant because an overlay tread rests on an existing tread and is self-supporting at the stair nosing. This combination of properties allows a profile of only 4.3 mm to be applied as a sturdy, dimensionally stable overlay tread.

Why thin and strong go together

Natural stone composite is a compound mineral material with recycled natural stone components, in which continuous fibres distribute forces across the entire profile. Strength is therefore not the property of a thick layer, but of the construction itself. The result is a profile that is stronger than structural steel — tensile strength 535 MPa, demonstrated by test report — and at the same time four times lighter than steel. And that makes a practical difference: the existing staircase barely has to carry any additional weight, and the build-up height remains so limited that stair nosings do not need to be shortened.

What you notice at home

For a home, these material properties translate into everyday certainty. A dimensionally stable profile gives a stable walking feel, and a hard mineral surface withstands ordinary home life — heels, pets, playing toys. The strength is in the material itself, not in a protective layer. The performance of a complete renovated staircase also depends on the existing substrate, the dimensioning and skilled installation — which is exactly why Omnistair works with selected installers.

What it means for projects and intensive use

For commercial buildings, apartment stairwells and public buildings, the same values weigh more heavily. Stairwells process thousands of passages per week, often concentrated on the same walking line. The compressive and flexural strength of the profile ensure that this load does not cause permanent deformation. EverStep Solid was developed for those environments: the same profile, finished with the SolidLux UV coating system for documented surface performance and immediate load-bearing capacity.

Honest about test values

The stated values come from an independent test report on standardised test samples of the profile and serve as an indicative guideline; actual performance may vary with dimensions, shape and processing. That is exactly why we never communicate a bare slogan such as "strong as steel", but always the figure with its source. Professional parties preparing a tender or project file can request the full test reports — so every value in a specification can be substantiated with the corresponding document.

In stair renovation, strength is not a sales argument but a basic property: together with good installation and normal maintenance, it determines how a staircase feels for years. All Omnistair claims and their sources can be found in the overview what the Omnistair claims are based on. Would you like to see the test reports or discuss the values for a specific project? Contact us via our contact page.