Attenuation of rainfall noise on metal roofing

Metal roofing is a popular construction material in many parts of the world, particularly in Australia, Asia and other areas of Oceania, with metal roofing noise being a common issue. While metal offers a variety of benefits, it tends to exhibit excessive impact noise during rainfall due to its minimal internal damping. The net effect is an increase in interior noise levels, particularly in the case of high rainfall rates also reduced speech intelligibility, and disruption of sleep or concentration.

To achieve effective rainfall noise reduction, introducing a high-performance vibration and noise damping compound to the highly resonant metal roofing is key. Applying a water-based acoustic damping material to the structure reduces the panel's resonance, making it less prone to excitation from rainfall impact, leading to lower airborne noise inside the building. Decidamp® SP80 has been specifically developed for building and construction acoustics, designed to deliver high performance in roof sound insulation and rainfall noise control. The compound is water-based, easily sprayable, and exhibits a high damping loss factor. It was tested on performance in this scenario - when applied to the underside of corrugated metal roofing at a dry film thickness of 1 mm, Decidamp SP80 significantly improves rainfall noise insulation. 

Independent acoustic testing to ISO 10140-5 was conducted at the University of Auckland, confirming performance improvements across the entire measured frequency spectrum for both airborne and rainfall noise insulation.

The test results revealed that Decidamp® SP80 is highly effective in reducing rainfall noise and increasing transmission loss of metal roofing. With minimal treatment, sound intensity was reduced by 10-11 dB and transmission loss (Rw) improved by 5-6 points. Decidamp® SP80 is a proven noise control solution on it’s own or as an element of a more comprehensive system for metal roof acoustics, especially when attenuating rainfall noise on metal roofing.

Tests demonstrated that Decidamp SP80 effectively reduces impact noise from rain and increases transmission loss when applied to the lower facing of corrugated metal roofing panels at 1 mm dry film thickness. Its combination of durability, ease of application, and measurable acoustic performance make it a reliable choice for architects and builders seeking to improve interior acoustic comfort and achieve rainfall noise reduction in modern building design.