How to reduce noise on a metal roof
A multi layered system is key to significantly reducing noise for a metal roof
Roof Decking
As an example, 5/8 OSB decking can reduce rain noise up to 10 decibels. It is important to remember that traditional metal structure roof framing is placed at approximately 4 or 5 feet spacing. Considerations must be made regarding loading, function and cost.
Insulation
Rain is considered a low frequency noise. The sound of rain hitting a metal roof can produce a continuous, thudding noise that is felt more as a vibration than as a sharp, distinct sound. Mineral wool is the best insulation for reducing rain noise on a metal roof. The key reason is its high density, excellent sound absorption properties, and resistance to moisture.
Unlike traditional fiberglass, mineral wool has a denser structure that effectively absorbs impact noise from rain. This prevents it from resonating through the metal panels. Its ability to trap and dissipate sound waves, especially in the low- to mid-frequency range, makes it particularly effective at reducing the drumming effect of rain.
Additionally, mineral wool is fire-resistant, water-repellent, and provides superior thermal insulation. This makes it a durable and efficient choice for both noise control and energy efficiency in metal roofing systems. It is reasonable to expect a noise reduction from 10 up to 20 decibels considering 6 inches of mineral wool.
Rigid Board Insulation
When considering rigid board insulation for sound reduction and moisture control, extruded polystyrene (XPS) is a good choice. XPS provides moderate sound reduction, typically reducing impact noise by 5-10 dB (2-3 inch thickness). This is due to its higher density compared to materials like EPS or polyisocyanurate. Considering other options, XPS strikes a balance, offering low vapor permeability to help control moisture, while also delivering better soundproofing than EPS and Polyiso. This makes it the best choice to achieve sound reduction and moisture resistance in a roofing system assembly.
Other Considerations
It's understandable that when constructing a new building or living space the primary objective is often one of speed. The goal being to ensure it can be used as quickly as possible to meet the functional needs of the occupants or business. However, It is important to carefully consider variables such as insulation, sound control, and vapor permeability when constructing a roof. These factors directly impact the comfort, durability and energy efficiency of the building. We often don't consider things such as designing around sound control until it's too late. A noisy metal roof can be deafening and uncomfortable when not designed correctly and greatly impacts the usability of the space. When the metal roofing system is designed correctly, it makes for a long lasting, efficient and high performing system to be enjoyed for years to come.