PET Felt vs Mineral Wool for Acoustic Treatment: Which Performs Better

Two different answers to the same problem

When it comes to absorbing sound in a room, PET felt and mineral wool both work. They work through the same basic mechanism - porous fibrous structures that convert sound energy to heat. The question of which one to use depends on the specific project requirements: performance, aesthetics, durability, health considerations, and cost.

Here's an honest comparison.

Acoustic performance compared

Mineral wool (including stone wool and glass wool) is a more open, less dense fibrous structure than PET felt at equivalent thicknesses. This gives it slightly better low-frequency absorption for a given thickness - mineral wool panels are somewhat more efficient at handling bass-range sound than PET felt panels of the same depth.

At mid and high frequencies - the range most relevant for speech intelligibility and echo control in offices, restaurants, and living rooms - PET felt and mineral wool perform comparably. A well-specified PET felt panel achieves NRC values of 0.65 to 0.85 depending on thickness and density. Mineral wool panels at similar thicknesses achieve similar values, sometimes slightly higher.

For general acoustic treatment in commercial and residential interiors, the performance difference between good PET felt and good mineral wool is not large enough to be the deciding factor in most projects. The practical differences dominate the choice.

Installation and handling

Mineral wool is an irritant during handling. The glass or stone fibres shed during cutting and installation and cause skin irritation and respiratory irritation. Protective equipment - gloves, eye protection, and dust mask - is required. The material is also loose and needs to be contained within a frame or cover.

PET felt cuts cleanly with a sharp blade, creates minimal dust, and doesn't irritate skin or respiratory passages. It can be handled without protective equipment. The finished edge is clean without the need for framing.

As a standalone visible panel, PET felt is the only option between the two. Mineral wool is always a core material that needs to be covered - typically with fabric, perforated metal, or another face material. PET felt is the panel itself.

Aesthetics and design options

PET felt is available in a wide colour range - typically 30 to 100 colours depending on the supplier - with clean, consistent colour that runs through the material. It can be CNC-cut into shapes, patterns, and profiles. It can be printed, engraved, or cut into decorative forms. As a visible surface material, it has significant design flexibility.

Mineral wool has essentially no design flexibility as a face material. It's always concealed. If the specification requires a visible acoustic surface - which is most interior acoustic applications - PET felt wins on aesthetics by default.

Fire performance

Stone wool (Rockwool) is non-combustible and achieves Class A1 fire rating. Glass wool achieves A1 or A2. PET felt, being a polymer material, typically achieves Class B or C unless specifically fire-treated. For applications requiring Class A1 - stairwells, hospitals, high-occupancy buildings - mineral wool has a genuine performance advantage that PET felt cannot match without significant treatment.

For most commercial interiors, Class B PET felt is adequate and meets specification requirements. Confirm requirements with the project's fire engineer before specifying either material in high-risk applications.

Sustainability

Good PET felt panels contain 50 to 100 percent post-consumer recycled content. This is a genuine environmental credential - the material diverts plastic from waste streams. Stone wool is made from volcanic rock, an effectively unlimited resource, but the manufacturing process is energy-intensive.

The sustainability comparison isn't simple, but PET felt's recycled content is a meaningful differentiator in projects with sustainability credentials or certification targets (BREEAM, LEED, and similar schemes reward recycled content).

The summary

For visible acoustic surfaces in commercial and residential interiors: PET felt. It performs well, looks good, handles cleanly, and has strong sustainability credentials. For high fire-specification applications or situations where maximum performance at low-frequency is required within a tight budget: mineral wool, usually as a concealed core. Most interior acoustic projects will be well-served by PET felt panels.