Acoustic Underlay

QA Flooring has witnessed an increase in demand for our acoustic underlay range, due to the following factors:

• Dense living – Meeting population growth demands, many homes exist as flats within multistory buildings. Many developers use our underlays to create barriers of sound reduction between tenants.
• Open floor plan—When a home is made up of one or more areas made into one overall room, it’s called an open floor plan. This is particularly common in modern homes, which feature kitchens, dining rooms, and living rooms all in the same four rooms. Having an acoustic underlay can help reduce how much impact sound and airborne noise travels throughout the room by absorbing it, not to mention stopping it from travelling beyond the room.
• Ease of application – Improving soundproofing through underlays is much easier and cheaper than hiring a construction crew to apply compounds to walls, decoupling wall systems etc. Not only this, but a soundproof underlay often serves several purposes that bring additional benefits to the home, such as improved comfort and moisture suppression.

Does QA Flooring’s soundproof underlay range work on any floor or subfloor?

This question can be split into two:

• Floor – We offer an acoustic underlay range in carpet, laminate flooring, and engineered wood (i.e. a timber floor).
• Subfloor – Our acoustic underlay range works on any subfloor, such as wood or concrete floors. Depending on the type of subfloor, we would recommend getting additional benefits, such as a moisture barrier for concrete floors.

Soundproofing underlay differs in terms of quality and material makeup, but we have created this table to detail industry averages:

A quick rundown of each type of underlay material, and its main uses:

• Foam underlay—Foam is a lightweight and cost-effective solution that is easy to install for even DIY beginners. It ensures a level surface even with imperfect subfloors. It is most commonly used as a carpet underlay. Whilst typically designed less with acoustic sound reduction in mind, QA Flooring has filled this demand with the most premium option in the carpet underlay market.
• Rubber underlay—Rubber is a heavier and denser material that offers high performance in preventing the wear of your flooring and in noise reduction. The quality of the impact sound reduction depends on the type of rubber in particular, with natural rubber being the strongest insulator and recycled rubber achieving mid-range quality. Rubber underlay is often used on hardwood flooring, installed with an isobond adhesive by ensuring the length of it is laid directly against the subfloor.
• Cork underlay – Cork underlays are created through sustainable harvesting, with cork being stripped from the bark of trees before being left to regrow. It is an effective, green choice for homeowners wanting both sound reduction and biodegradability and is often used with laminate flooring.
• Felt underlay – Felt underlays are usually the go-to choice for applying a soundproofing underlay for laminate flooring, as they are constructed in layers. The felt itself is used to provide thermal insulation, whilst the foam side is what’s responsible for impact and airborne noise reduction.

No. Although the thickness of your soundproof underlay can contribute to its acoustic insulation ability, it’s entirely possible for acoustic insulation underlays that are less than half the level of thickness of another to outperform in the realm of acoustic insulation.

Let us quickly go through the different factors:

• Thickness – Thick underlays can reduce the energy of acoustic waves against the floor. This is because the sheer amount of material makes it effective in cushioning and absorbing airborne sound, such as with a PU foam carpet underlay.
• Density – Dense materials are dense due to the high amount of packed molecules. These molecules capture the waves of impact and airborne sounds and convert them to a different type of energy, such as heat. A rubber underlay typically has the most density in the market and is often used in areas with heavy foot traffic.
• Material Composition – Different materials have different abilities to resist the flow of acoustic energy. Materials like rubber and cork have structures that give them a high ability to dissipate sound energy.
• Type of Sound – Sounds have different waves. Just like how different wavelengths of light determine its colour, different wavelengths of sound determine how easily it dissipates. For example, airborne and impact noise are two different types of sound. Airborne noise includes things like TV noise and music, whereas impact sounds consist of footsteps and similar movements directly on the floor.

Yes, it’s entirely possible. That being said, there are some things to consider, as an acoustic underlay tends to be thick and/or dense, both of which can make it hard for underfloor heating to be efficient. As such, ensure you check the following:

• Thermal Conductivity – For the heating to properly enter and heat the room, the floor has to be highly conductive to heat. Conductivity is the measure of how easily heat can go through the material.
• Thickness – A thick underlay is typically a good insulator, meaning that it’s designed to keep the room warm by keeping heat inside of it. However, the underfloor heating is typically on the other side of this barrier, meaning all the heating is trapped underneath the floor if the insulation is too high.
• Material – Some materials are simply not that good for transmitting heat. For example, polystyrene foam, and a lot of rubber products. It’s unlikely that products that have these will do an effective job. You should look more towards Polyethylene foam, for example, those coated in aluminium.

Yes, an acoustic underlay can indeed help reduce vibrations. The impact noise of feet against the floor usually results in vibrations that travel through the ground.

• Impact Noise Reduction – Impact noise occurs purely due to vibrations made through the floor from said impact. Acoustic underlays primarily absorb sounds, such as airborne sounds and increase impact sound reduction. Sound vibrations are particularly noticeable when the underlay is on floors above the ground floor. 
• Dense Materials – Dense materials are highly effective against dissipating vibration. These materials can be rubber or high-density variants of foam. The molecular makeup of these materials makes their ability to absorb and kill vibration (and sound) incredible. 
• Decoupling Effect – Some underlays have what’s called a decoupling effect. This refers to the ability of the floor to interrupt the path the vibrations travel, therefore killing it mid-flight. This is done by creating a layer of separation between the floor and subfloor. If there’s nothing to travel through, then there’s nowhere for the vibration to go.
• Barrier layer – Some acoustic underlays have what’s called a mass-loaded barrier layer. This adds mass to the flooring, making it harder for vibration to pass through as there’s simply too much mass for it to affect.
• Resilience – There is an anti-compression effect within acoustic underlays that allows it to absorb the shock of impact.

Sound is a wave, and it bounces off of objects much like light does, albeit with varying effectiveness. With an acoustic underlay, sound can bounce off of the floor and keep the sound within the room. This can not only help with immersion, but it can also help with not disturbing others.