Steel Buildings in Europe

Part 8: Building Envelope 8 - 19 3 1 2 1 Impact noise from rain 2 Reverberation 3 Airborne sound transmission Figure 3.3 Categories of acoustic performance 3.5.2 Reverberation In certain applications, such as offices or residential accommodation, internal acoustic performance might be critical to the functionality of the building. Of particular interest is the reverberation caused by sound waves reflecting off hard internal surfaces, including elements of the building envelope. Typically, the internal finishes of the building will be used to limit reverberation, but architects may also take advantage of the sound absorbing properties of the cladding insulation layer by replacing the standard liner sheet with a perforated liner. Where the envelope consists of insulated sandwich panels, it is not uncommon to install a perforated liner and a layer of mineral wool insulation on the inside of the envelope in order to reduce reverberation. 3.5.3 Impact noise The noise created by the impact of rain or hail on metal roof sheeting can sometimes create a nuisance for the building occupants. Where impact noise is considered to be important, it can sometimes be reduced by placing a flexible insulation layer directly below the outer sheet to act as a damper. 3.5.4 Noise associated with building services equipment Consideration should also be given to attenuating noise emanating from services equipment. These include providing sound enclosures for noise prone machinery and/or including equipment supports with dampers. Reduction of noise from services is particularly appropriate in industrial buildings. National regulations may specify acoustic performance standards in terms of reducing noise coming into a building – but these are often for residential buildings. 65 dB is generally considered a suitable indoor noise level in industrial buildings, whereas 50 to 55 dB is considered a suitable indoor ambient noise level for commercial, retail and leisure buildings. For industrial buildings, noise break-out is usually a greater concern. Local regulations may