Serviceability criteria

The three perceptible characteristics

Deflection

The movement of the structure under load. Visible, and it affects the finishes. Deflection limits.

Vibration

The floor’s response to footfall and movement. One of the most important quality questions in light gauge steel construction. Floor vibration.

Cracking

Hairline cracks appearing at junctions in the finishes. They often come from movement of the structure or from differential movement of the materials.

Why the minimum in the standard is not enough

The standard gives recommended values, but they are minima and they do not know the expectations of the particular project.

Two examples:

• A rigid, ceramic-tiled floor calls for a stricter deflection limit than a resilient floor covering.
• An open-plan office and a corridor above a bedroom place different demands on vibration.

How it has to be handled

Fix it in advance

At the start of the project, in writing: what the finishes will be, what is expected of the feel of the floor, whether there is a special need.

Design it with the build-up

Mass and damping come from the build-up, so the structural and the build-up decisions are linked. Floor build-ups.

Handle the expectation together with the cost

A stiffer structure and a heavier build-up cost more. The client has the right to decide what that is worth to them — but they can only decide if they know what is at stake.

What the technology offers

Light gauge steel build-ups have many degrees of freedom: by choosing the layers, the sound insulation, the feel of the vibration and the thermal performance can be tuned relatively independently. This technology offers more scope for a good solution than the traditional one — you just have to use it.

The point

The serviceability criterion is what the occupant calls “quality”. The standard is the minimum — the expectation has to be settled at the start of the project.