SOUND SOLUTIONS FOR BUILT UP FLAT ROOFING
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A sound solution for built-up flat roofing

Rain noise testing on lightweight roofing The combined acoustic benefits of ROCKWOOL® 4 in 1 insulation & ROCKFON® ceilings By Tim Spencer FIGURE 01 A ROCKWOOL® roofing system being installed

Introduction To be (as we believe) the first organisation in the UK to complete testing in accordance with the published version of ISO Standard BSEN ISO 140 – 18:2006 Measurement of rain noise on building elements [1] was quite an achievement for ROCKWOOL® Ltd. BS EN ISO 140-8 describes a laboratory method for the measurement of sound generated by rainfall on building elements, using artificial raindrops produced by a water tank. Ideally, test specimens should be exposed to real rain for such measurements. But real rain is neither steady nor continuous with respect to time. Furthermore,...

Test Programme The comprehensive test programme was completed at the BRE acoustics laboratory within the extensive Building Research Establishment at Garston, Watford in November and December 2007. BRE Acoustics specifically configured one of their existing laboratories to allow for the construction of roofs and ceiling elements together with the ‘rain’ water tank and all of its necessary supports allowing for easy tank movement so that measurements could be made in different roof positions. The rig also included water run-off and collection systems, water collection and recycling being...

Why do the tests? Appropriate background sound pressure levels and the need for appropriate levels of resistance to noise generated by rain are ‘must haves’ in modern buildings. In any built environment, an appropriate background sound level should not be exceeded no matter what the weather conditions. In design work the sound pressure level due to rainfall in the Appropriate background sound pressure levels and the need for appropriate levels of resistance to noise generated by rain are ‘must haves’ in modern buildings. In any built environment, an appropriate background sound level should...

Results Room Type Area Height Ceiling Primary classroom Primary classroom Secondary classroom Secondary classroom Lecture room large Lecture room large ROCKFON® 50mm Sonar 44 dB‘sandwich’ 50 ROCKFON® 50mm Sonar 44 dB‘sandwich’ 50 ROCKFON® 50mm Sonar 44 dB‘sandwich’ 50 hearing impaired Sample performance in Schools Note: Lower values of internal sound pressure level indicate a better performance. All ceilings consisted of Rockfon tiles in 600mm x 600mm modules and a RockLink 24 exposed grid. The roof construction without a suspended ceiling performed well, achieving 59dB LAeq,30min (based on...

Test Programme Rainfall Rainfall Typical Drop Fall Velocity Type Rate mm/h Diameter mm ms Classification of rain type according to IEC 60721-2-2 A tank positioned above the test roof is filled with water and constantly recharged. The flow rate is calibrated and monitored to ensure a correct rainfall. Sound pressure level measurements are taken below each roof or roof/ceiling construction in the frequency range 100Hz to 5kHz. The rain noise standard describes various types of artificial rainfall that can be used, as shown in Table 2. Real rain can be classified in terms of rainfall rate,...

Sustainability Finally, a word on sustainability, understandably a subject of increasing popularity and one that is quite rightly entering into and becoming part of an ever-increasing holistic approach by acousticians. The diabase rock from which ROCKWOOL® insulation and Rockfon ceilings are manufactured possesses a rare quality among the many types of raw materials used to manufacture insulation. The natural process by which diabase is formed is taking place continuously all over the world. Volcanic activity and plate tectonics mean that mother nature creates new reserves of diabase rock...