Which Of These 3 Acoustic Underlays Is Best For Your Floor?
So you have decided that you need acoustic underlay under the floor in the project you are building, designing or renovating. What next?
Understanding the different materials used to make acoustic flooring underlay will allow you to select a product that matches your floor type, performance requirements, budget and eco credentials.
At Pliteq, we manufacture and sell acoustic flooring underlay made from re-bonded recycled rubber (predominantly recycled car tires) but the truth of the matter is an acoustic underlay made from recycled rubber may not be the best choice for you and your project.
However, we can educate you on what is available on the market so you can make an informed decision that is best for your project.
What flooring will you be installing over your acoustic underlay?
The flooring you intend to specifying or install over the acoustic underlay mat effects the choice you make. Some underlays are not suitable for use under some flooring types so in this section will provide a few details on things to look out for with the most common flooring types.
Vinyl Plank/Tile Floors
Vinyl flooring is definitely not new, but it is certainly the new kid on the block on this list in its latest tile and plank format. It has become increasing popular in all building types for its ease and speed of installation as well as its vast array of colour and pattern formats.
Like with the original sheet vinyl format, the quality and price vary greatly. The two main things to check are the overall thickness of the plank/tiler and the thickness of the upper wear layer. Remember less raw material may equal lower cost but this may have an impact on the longevity further down the line.
Now you are probably asking what does this have to do with acoustic underlay? Well as you might expect the thinner the vinyl tile/plank product, the more flexible it is likely to be and therefore the more likely it is to flex and indent under furniture feet point loads AND if you have a soft underlay (like foam on felt) beneath it you will likely feel the vinyl floor move when you walk across it. Now some people like this “comfort” feel but it is not to everyones taste.
A good way to assess this to check if the underlay has a test to ASTM F924 (puncture testing), ASTM F1265 (resistance to impact) and ASTM F2753 (rolling load indentation). The last one is particularly important if you intend to use a desk chair on the floor!
It is therefore recommended that a firmer underlay like cork or recycled rubber is used beneath vinyl plank/tile floors if you want to avoid that bouncy feel or are worried about indentation.
Ceramic/Marble/Porcelain Tiled Floors
Masonry flooring is extremely rigid and can be hugely expensive. It does not like being installed on uneven or soft surfaces and the last thing you want is your beautiful marble floor cracking!
Therefore it is not normally recommend to specify or use a masonry tile floor over a foam or other overly soft acoustic underlay (<500 kg/m3) as the foam or other soft type of underlay will compress over time which will cause the tile to move and eventually crack.
If you are unsure, request an ASTM C627 test from the underlay supplier or manufacturer. A rating of light commercial or higher is recommended which will provide you with confidence that your floor will play happily with your floor underlay and you can avoid cracking tiles!
Solid, Engineered and Laminate Wood Floors
Wood floors are less dense (hard) than masonry floors but denser than a vinyl plank/tile system and come with a different set of issues to be aware of compared to the other two flooring types.
There is a tendency for wood floors to change in size and shape given time and changing room temperatures. Even without a flooring underlay involved this can cause problems like curling, warping and as a result squeaky floors. ut it this way, you’ll never be able to creep undetected to to the fridge in the middle of the night! But like with vinyl tile/plank flooring systems just check the specifications of the floor and check samples to make sure you are happy with the quality. A good installer will also help you avoid these issues.,
It is therefore recommend that a floor underlay mat that is firm enough to avoid immediate squeak and movement whilst also being able to flex and move with your floor over time is essential.
Most Popular Types Of Acoustic Underlay
Ok so we have looked at the 3 major types of flooring now it is onto the flooring underlays. It should be noted that there are more than 3 types available, but in our experience of the commercial underlay world these are the most commonly installed.
Foam Acoustic Flooring Underlay
This is the most commonly available consumer focused underlay on the market. Foam underlay has a number of benefits:
- It’s low cost
- Readily available at big box stores like Lowes and Home Depot
- Lightweight (<100 kg/m3) so easy to carry up stairs
- Comes in sheets and rolls
- Good impact sound insulation under wood and vinyl flooring
However it has its draw backs:
- Can have 4 kg of CO2 per kg of product (Cork has 0.2 kg) – Not great if your are wanting to use sustainable building products.
- It cannot be directly used under masonry tiled floors
- It is prone to compression over time as the bubbles inside pop
- Acoustic test data can vary wildly with some high IIC/Lnw numbers quoted so do read up on how to read acoustic test reports.
- Huge range of quality
This reason for the high level of embodied carbon is because it’s made from petroleum or natural gas.
It’s a good choice for the average home owner looking for improvements within single family homes and it is commonly used in commercial residential property as a way to save money but this is not terribly sustainable as it may cause issues in the long run with higher tenant turn over and maintenance issues with floors.
The quality of foam may also vary due to it being so common. Many forms of it are available, and that makes it hard to pinpoint which one has the best quality.
Cork Underlay
Cork, yes cork! Think of all the wine you’d have to drink to create a flooring underlay! Joking aside cork underlay is normally made from the waste from the process of making corks for wine bottles (amongst other things). It is also commonly mixed with foam to create underlays for various applications so make sure you choose one suited to your flooring type. The ones mixed with foam are generally softer and so check they have the ASTM C627 test mentioned earlier before using them under masonry tile floors.
Like foam, cork is also lightweight (250-45kg/m3), making it easier shift around and install. However it is stiffer then foam so can be less effective than foam or require a greater thickness to get the required acoustic performance. For example a 1/2″(12.5mm) cork underlay will achieve the same impact noise attenuation (IIC/Ln,w) as a 3/16″ (5mm) recycled rubber acoustic underlay when installed under ceramic tile on a (150mm) concrete slab.
The downside of cork is that it lacks structural testing with tile and may not be able to provide acceptable impact noise ratings in difficult sound control situations. Due to its nature, cork becomes stiff and can lose resilience and effectiveness over time.
Rebonded Recycled Rubber Underlay:
Recycled rebonded rubber is not commonly used by single family home owners as it is less abundant in big box stores but is very commonly installed large residential schemes and hotels where product longevity and consistent acoustic performance is key.
As the names suggests it is manufactured using recycled rubber. Some manufactures will mix a variety of sources of rubber including off cuts from the medical and flooring industry which will lead to a multicoloured product. Others will use solely scrap rubber from vehicle tyres which will make the product all black with just a few white speckles which come from the names written in the sides of the tyres.
This a great use of a material which would otherwise be burnt or put into landfill.
There are far less manufacturers of recycled rubber acoustic underlay so it is much easier to find good quality product. Typically products will range in density from 750 kg/m3 to 1050kg/m3. This density lends itself very well to being used under all floor types without the worry of indentation when used under vinyl tile/plank or cracking when used under a masonry tile floor. However this does not mean they are all created equally! So triple check with your manufacturers information.
This density does make then heavier and therefore harder to move around but they are commonly available in sheets as well as rolls for greater ease of installation.
Its acoustical performance is top of the stack and there is plenty of reputable testing available but agina make sure you know how to read the tests! At a thickness of 5mm it can reduce up to 19 dB in the higher frequency (high heel shoes on hard floor sound) range. This is mainly down to the natural resilience of rubber which is why it is so commonly used in noise and vibration applications not only in buildings but also in cars and trains.
The life expectancy of rebonded recycled rubber is also longer compared to other options as it does not age or harden, and is resistant to water and mold.
Only a minimal thickness (5/64″ or 2mm) is needed for it to perform up to standards in a typical 8″/200mm concrete construction and any floor type can be directly applied to it, to floor finishes including ceramic tile. The material is made from disposed rubber tires, so it is sustainable and great for the environment. The downside is that it is heavy compared to the other options on the market, and due to its wide range of forms available on the market, its quality can be hard to pinpoint and can vary by a lot.
So this rounds out this part of our acoustic underly series. So remember:
- Check your flooring is compatible with the underlay you are looking at specifying or installing
- Check the underlay has the correct robustness testing for your application
- Check the acoustic test data
- Check you are happy with the sustainability of the product.
If you want to know more get in touch!
