The “Questions and Answers” section should help you find answers you need. If you don’t find the information you’re looking for, do not hesitate to ask your question.

How should you choose a subfloor soundproofing product?

There are many subfloor products on the market. To make an informed choice combining performance and durability, it is essential to know what to consider.

The subfloor membrane must act as a vapour barrier, since the wood reacts to moisture. To maintain its acoustic performance, the subfloor membrane must be resilient, which means it must remain stable without sagging over time.
In addition to these two essential elements, several other criteria must be considered and compared to choose the right product:

  • The installation method
  • Its compatibility with complementary products (e.g. adhesive and mortar)
  • Product knowledge of installers
  • Membrane thickness
  • Compliance with various programs (e.g. LEED and Novoclimat)
  • Results of various acoustic tests (e.g. FIIC, FSTC and Robinson)
  • The anti-fracture characteristics (for a membrane applied to ceramic)
  • Etc.

Discover the RESISTOSOUND products that are available to you for soundproofing your floor.


How to interpret the results of FIIC and FSTC indexes?

FIIC normalized impact noise insulation index: This index consists in testing the transmission coefficient of impact noises (e.g. footsteps, falling objects, and knocks).

FSTC sound transmission index: This index measures the transmission of airborne noises (e.g. voice, television, and music).

In both cases, the higher the number, the better the noise reduction. Both indexes are not necessarily related; that is to say a good FIIC does not necessarily mean a good FSTC, and vice versa. However, since impact noise becomes airborne noise a fraction of a second after the impact, it is clear that a good FIIC index promotes a better FSTC index.


What are performance indexes?

Acoustic performance of a system is defined by two indexes: the IIC (Impact Insulation Class) for impact noise and STC (Sound Transmission Class) for airborne noise. To get even closer to the real conditions, we can test acoustic performance indexes on construction sites. In this case, the indexes presented are preceded by the letter F to denote the concept of construction site (Field). It is important to note that the FSTC and FIIC results are generally lower than the STC and IIC results since control is lower on a real construction site than during laboratory tests. However, they are closer to reality.

What is the difference between sound absorption and sound insulation?

Sound absorption of a wall consists of preventing the sound from switching from one side of the wall to the other side without creating reverberation. The objective is to minimize the sound perceived from the opposite side of the source without amplifying noise perceived inside the emitting room by reverberation phenomenon.

Acoustic insulation of a wall consists of preventing the sound from passing from one side of the wall to the other side. Therefore, the objective is to minimize the sound perceived on the opposite side from the source of noise.

What is the difference between sound and noise?

First of all, sound is an acoustic vibration that propagates in the air and causes an auditory sensation. A sound is mainly defined by two parameters – the frequency (or pitch) and the volume (or intensity).

The intensity refers to the force of the sound. Sound intensity is measured in decibels (dB). It can range from 0 dB to 194 dB. A sound that reaches the maximum intensity of 194 dB can certainly affect your sense of hearing.

Verbal discussion: between 45 and 55 dB
Background noise in a room: about 28 dB
Phone ringtone: about 80 dB
Vacuum cleaner: between 60 and 85 dB
Television: about 70 dB
The frequency refers to the tone of the sound. Frequency is measured in hertz (Hz). Human beings can perceive frequencies between 20 Hz and 18,000 Hz, and animals perceive frequencies beyond what humans can hear.
Noise, for its part, is a set of sounds produced by irregular, unharmonious vibrations. It is often perceived as a nuisance.

What is the difference between airborne noise and impact noise?

In the field of building acoustics, two types of sound transmission exist.
Airborne noise: Airborne noises are transmitted by air and atmosphere. The radio, or people carrying on a conversation, are good examples of airborne noises.
Impact noise: Impact noises propagate through solids and result from a shock on them. The footsteps of a person and the sound of an object falling on the floor are examples of impact noises.

What are building acoustics?

Nowadays, noise is a major source of pollution. Since noise in a building can easily travel through air, materials, openings and structures, soundproofing is an essential element to be considered early, at the design phase of the building.

Is concrete a good sound insulator?

Concrete is an excellent acoustic insulator from airborne noises. However, since concrete is a very hard material, it reduces the acoustic performance in terms of impact noises, which it conducts.

When designing a building, the selection of a structure with or without concrete should be considered. In the case of a building with five or more floors, there is no choice because the National Building Code requires a structural concrete slab. It is recommended that you use soundproofing products specifically designed to increase acoustic performance by reducing impact noises.

Does an acoustic membrane have a specific acoustic index?

NO. The index is determined by measuring a complete assembly in which the membrane is used. No regulation requires manufacturers to explain how they achieved their acoustic performance results. However, always ask for the full details of the floor/ceiling assembly associated with acoustic indexes presented, in order to be able to compare them to your actual project.

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