Phone Email

Sound insulation: verification and prediction

Two questions that are regularly confused. Verification shows that a component protects sufficiently against sound from the neighbouring room. Prediction says how loud it will be at a given place in future. They follow different sets of rules, need different input data and answer different questions.

What makes the difference

Verification calculates inwards: separating area, room volume, flanking components. Prediction calculates outwards: source, propagation, screening by buildings and terrain.

Verification

The governing standard is DIN 4109, sound insulation in buildings. The calculation uses component ratings and geometry: the separating area between the rooms considered, the volume of the receiving room, the openings and the flanking components with their junctions.

In a new build these quantities fall out of the design model. In an existing building that model does not exist, and the building file records the state at the time of construction, not the state after forty years of alterations. From a survey, by contrast, the dimensions can be read off instead of being carried over from old drawings.

What a survey does not supply is the build-up of the component. No scanner can see whether a wall is 24 cm of masonry or two layers of plasterboard. That information comes from the building file, from opening up a component or from a measurement on site — and without it no verification holds.

Prediction

Here it is about noise from outside: traffic, industry, plant. The calculation follows the propagation from source to receiver, and screening comes from whatever stands in between — buildings, embankments, terrain edges.

A prediction therefore needs the same basis as a site assessment: the massing of the surroundings, terrain heights, orientation. Without it, estimates take over — and screening is precisely the part where an estimate tips the result.

Where the data comes from

From the same survey that produces floor plans, the room book and the as-built model. Clear heights, room areas and opening dimensions are in the room book anyway; the verification calculation only needs them in the right structure. The surroundings for the prediction come from drone surveying and the terrain model.

Further reading