A tin roof will never keep the calm that characterizes a brick or stone roof when it rains. In almost all cases, the noise can be reduced to a bearable level when it rains. Some basic considerations on sound development and sound propagation are helpful for this. Small tricks create significantly improved acoustics.
Most of the causes can be influenced acoustically
The legend that it is almost always unbearably loud under tin roofs when it rains is fed mainly from imperfectly or freely swinging sheet metal, which actually produce subjectively unbelievably loud noises.
Modern sheet metal roofs can be reduced to almost the same level of noise as other "quieter" materials by means of building acoustically effective methods and constant advances in material development.
The following factors acting on acoustics are responsible for noise:
- Type of attachment
- Fastening site and decoupling from the carrier (sound bridges)
- Residence distance to the roof
- Shape of the sheet (flat, smooth, trapezoidal, wavy)
- Size of raindrops
- Hall effect in the room (empty and textile free)
- Borne noise (membrane and resonance)
- Air sound (vibrations)
- Quantity of falling rain
Except for size and amount of raindrops, all other factors can be influenced structurally.
- Anti-mood coating as you can also find under hoods of vehicles (rubber or foam mats)
- Decouple by elastic sleeves on attachment points to the substructure
- Landed glued sound insulation for prevention of the membrane and vibration effect
- Subsequent dams through rigid struts
The relevant structural standard is DIN EN ISO 10140 for the acoustics measurement of components in the test bench, change two to rain noise. One problem is the subjective perception of people about the annoyance and noise limit. With a professional design, rain noise on every tin roof can be reduced below this threshold.
The following video shows the sound of rain pounding on a roof for just under two minutes. It allows the test of whether this sound is perceived as calming or disturbing: