Last updated: March 8, 2022 at 11:30 am
Acoustic underlay is yet another weapon in the search for complete soundproofing. Laying it under different flooring types not only improves soundproofing, but has a few other benefits as well.
In this article:
We’ll run through what makes acoustic underlay different from standard, and what type of underlay you should be looking at for carpet, vinyl and wood flooring.
IN THIS ARTICLE
What Is Acoustic Underlay?
Acoustic underlay is a specific type of underlay which is designed to reduce noise transmission between floors. It is effective at reducing both impact and airborne noise because it decouples the top layer of flooring from the underfloor, preventing sound waves from passing through.
It’s one of the easiest types of soundproofing to fit if it is added while the floor is being laid. Acoustic underlay comes in different brands, but most often, it is a thick, flexible layer of rubber that lies underneath the floor accompanied by a flanking strip around the edge to isolate the floor from the walls.
It is a versatile product as it can be used on top of both concrete and timber floors. You can also install whatever type of flooring you require on top, including carpet, vinyl, and wood flooring. In addition, it comes in a roll that you can easily cut to fit the size and shape of your floor.
Acoustic underlay goes by a multitude of names online, depending on where you’re buying it from. Here are a few names you can be on the lookout for:
- Impact Mat
- Rubber Mat
- Soundproof Mat
- Sound Mat
- Acoustic Underlayment
- Resilient Underlay
How Does It Differ from Normal Underlay?
There are three main purposes to traditional underlay. The first is to smooth out any imperfections in the subfloor so that the floor feels uniform when you walk on it. The second purpose is to support your floor and prevent damage or uneven wear. Finally, it adds a cushioning layer for improved comfort when walking on your floor each day.
All these factors apply to acoustic underlay too, but there are two key differences. To block sound, you need to use a soundproof material and you also need more mass. Most regular underlay is less than a centimetre thick and won’t do much to prevent sound from passing through it.
The most common sound-absorbing materials used for acoustic underlay are cork, rubber and polyethene foam. Most acoustic underlay is a minimum of 12 millimetres and goes as thick as 18mm. Believe it or not, this extra mass will make a big difference in the sound transmitted between the floors of your home.
What Main Benefits Does It Offer?
The point of acoustic underlay is to isolate the floor from the subfloor and walls to stop flanking noise. Flanking noise is when sound travels from one room to another in some other way than straight through the walls. So, it could be sound travelling from one storey to another.
Or it could be an impact on the floor travelling up the walls and through to another room. The effectiveness of different brands varies, but as a guide, acoustic underlay should reduce airborne sound transmission by at least 45 dB and impact sound transmission by 50 dB.
Keeps in Heat
If your subfloor is made from concrete, it can get very cold. This can affect the temperature of your floor and your home. If your subfloor is timber, then heat can very easily escape through it. Acoustic underlay is made of a thick layer of rubber or cork which adds an extra layer of insulation. This will help keep the heat in and potentially reduce your heating bills a little.
Whether you have a concrete or timber floor, both are very hard surfaces to walk on. Even a thickly piled carpet can only do so much to cushion your feet. Acoustic underlay is a thick rubbery layer that will make any type of flooring more pleasant and comfortable to walk on.
Extends the Life of Your Flooring
Acoustic flooring adds a cushioning layer that supports whichever floor type you have. This additional support will prevent excessive wear and extend the life of your flooring.
One of the ways dust enters your home is up through the floor. This problem is worsened by air blowing in too and causing the dust to rise and move about your room. Not only does this mean you’ll need to dust more often, but it can also cause problems for any allergy sufferers.
Dust is known to make allergies worse. Having an extra layer under your floor means it’s less likely that dust and air can get in.
Where Can Acoustic Underlay Be Used?
Acoustic underlay can be used regardless of what type of subfloor you have and what type of flooring is going to be laid on top. Sometimes, the underlay will need extra support rather than just being fitted directly to the subfloor. In that case, a piece of chipboard can be glued onto the subfloor and then the acoustic underlay is placed on top.
Regardless of the type you use, make sure all the joins are securely taped to ensure the underlay doesn’t move. You may also consider adding a layer of acoustic sealant where the underlay meets the walls to seal up any gaps.
If you’re fitting acoustic underlay under carpeting, you can simply glue the underlay onto a concrete subfloor. You can glue it onto a timber subfloor, but you can also choose to nail or screw it down if you’d prefer to.
You can choose to have another layer of traditional underlay on top, and if so, you will need to fit perimeter rods around your acoustic underlay. This will allow carpet gripper rods to be fitted on top. However, as acoustic underlay is already thicker and bouncier than normal underlay, an extra layer should not be necessary.
Vinyl flooring comes in different forms – it can be a roll like carpet or linoleum, or planks like laminate flooring. You can use acoustic underlay under both types, but the installation method you use will need to match.
However, unlike under carpet or wood, many manufacturers recommend you do not glue or attach the underlay to the subfloor in any way. You simply place the underlay on the subfloor, ensuring that it lies smoothly, and then install the vinyl flooring on top.
As wood flooring is not as flexible as carpet, you will need to take extra steps when installing acoustic underlay. Firstly, if you’re using an underlay that comes in sheets rather than a roll, you should lay them at a 90° angle to the way the fitter will install your flooring. This is to ensure that the joins don’t line up because this could potentially weaken the floor at those points.
Secondly, to provide a stable surface for the wood to lie on, most manufacturers recommend fitting a layer of chipboard. Some manufacturers specify you should fit it under the underlay and others say to put it on top. Make sure you check what the manufacturer of your underlay recommends before attempting to fit it.
Finally, the brand you choose will affect how close your underlay should get to the walls. Some types of acoustic underlay have a moisture proof layer and recommend the underlay goes a few millimetres up the wall. Others say you can fit it up to the walls, and some others recommend leaving a gap between the walls as an extra sound break. Again, check the manufacturer’s installation instructions carefully before you begin.
As a wood floor is harder on your feet and more prone to transmit noise than carpet is, you should consider one of the thicker types of underlay.
If you’re struggling with noise between floors in your home or live in a flat and have received noise complaints from neighbours, it is worth considering acoustic underlay. If your floors are already laid, it may be inconvenient. But, it may well be worth it to restore peace and harmony in your home.
Acoustic underlay is relatively easy to fit and comes in many styles and thicknesses, so it should be easy for you to find one that suits your needs and your budget. Make sure you do your research, find out what type of installation is required and that the product and the company selling it got good reviews from previous customers.
As with all kinds of DIY, preparation is key.