A Buyer's Guide to Underlay


Underlay – it’s like milk in your tea, bubbles in your bath, petrol (or diesel) in your car. You can’t have flooring without having underlay, simple as that.

However, while it may quite literally be a fundamental layer within the process of choosing and purchasing new Carpet underlay, laminate underlay or other flooring; it’s easy to overlook. Yes, we see underlay when we’re buying it and when it’s being fitted, but then it’s out of sight and out of mind for however many years your new flooring’s down for. As a result, it can be easy to forget about factoring in underlay until the next time comes for you to invest in some new flooring, which means what you decide on may not necessarily be the best option.

To help make sure your next underlay decision is the best one, we’ve listed 4 key questions you should always ask yourself when shopping around for new flooring. But before we move on to the practical advice, there’s just one thing we wanted to address…..

You may be wondering if you even need new underlay; seeing as it’s never seen by anybody; it’s protected by your actual flooring, so is less likely to wear down that quickly and, because it’s under your flooring, it doesn’t matter if it’s particularly brand new. But here’s the thing, it does matter. Ideally, you should replace your underlay every time you get new flooring. Why? Because over time, underlay breaks down from the weight of being walked across, and within all of these gaps, dirt and bacteria can build up (a bit like how dust and skin cells can mount up in your mattress).

Top tip: Underlay can last for up to 25 years. If your carpet is flat or hard in areas, it could be a sign you need some new underlay.

…..Now back to those all-important questions you need to ask yourself when it comes to making your next underlay purchase:

Underlay FAQ's:

While it may sound like a bit of an obvious thing to think about, what your underlay’s made out of is crucial in making sure it provides maximum comfort, helps your flooring last longer and provides an extra layer of insulation and noise reduction.

However, it can be a bit of a minefield when you start to look because underlay is manufactured from so many different materials, including polyurethane foam (made from recycled furniture foam and a good heat and sound insulator), crumb rubber (hard-wearing and durable), waffle (good sound barrier and extremely comfy), XPS foam boards (made from foamed polystyrene that doesn’t deteriorate) and luxury vinyl (fitted underneath luxury vinyl tiles and provides good sound and thermal absorption).

There are also eco-friendly underlay options out there that are helping tackle the global plastics pollution crisis. They include SpringBond®, which is made from recycled PET plastic bottles and other single use plastics. Meanwhile, there are also carpet ranges made from discarded marine waste – Sedna® carpets take waste, such as old fishing nets, and turn it into soft, luxurious and durable carpet. What’s more, Sedna® carpets are also fitted with an ECO FusionBac textile back made from 100% recycled PET plastic bottles.

Top tip: Crumb rubber underlay is incredibly springy, which means it’s more likely to spring back after having heavy items (e.g. furniture) placed on it.

Thickness is a critical factor when it comes to underlay because it influences how comfy your flooring is and how effective it is at retaining heat and preventing sound from echoing around your house.

Generally speaking, underlay is available in a variety of thicknesses, ranging from 7mm to 12mm. Anything around the 8mm to 12mm mark is considered to provide an adequate amount of support. While the TOG rating, just like the TOG rating that’s used for duvets, indicates how effective underlay is at preventing heat from escaping. The higher the TOG rating, the better the heat retention.

Top tip: If you’re getting thicker underlay, the gap between your flooring and the bottom of your doors will be smaller. In some instances, you may need to get your doors skimmed to make sure you can still open and close them.

Ideally, you should have underlay underneath all of your upstairs and downstairs flooring because it will, among many things, help prolong the life of your flooring. But that doesn’t mean you should have exactly the same underlay throughout your entire house.

For instance, firmer underlay is better for areas where there’s more wear and tear and heavy items placed on it, such as your living room or stairs. Because it’s firmer, it helps prevent your flooring from moving and, in the case of carpets, creasing and stretching. Meanwhile, softer underlay is better suited to low traffic areas; such as your rarely used spare room or downstairs toilet, where it’s less likely to be trampled on all of the time.

Top tip: 9mm underlay is the best thickness for stairs; it’ll provide the right amount of cushioning without being too bulky to fit.

What you intend to put on top of you underlay will influence the type of underlay you have. For example, rigid underlays made from plywood and MDF are used for wooden flooring because they provide a level foundation, distribute weight load evenly and help reduce movement.

In comparison, softer underlays made from materials, including foam, rubber and recycled plastics, are used underneath carpet. Depending on the thickness and type of insulation you go for, they provide varying degrees of padding and sound and heat insulation.

Certain types of underlay also exist for hard flooring too, some of which incorporate special damp-proof membranes within their overall structure.

Top tip: Match your underlay to your flooring type. Don’t assume that one underlay will be suitable for your whole house, especially if you have a mixture of carpet, laminate and tiled flooring.



Underlay plays an incredibly important role in perfecting your flooring and making sure it lasts. Taking the time to think about the practicalities, and asking yourself questions like those listed above, will help guarantee the underlay you choose is 100% right now, and for many years to come.

At ScS, we also offer underlay suitable for underfloor heating - for those living spaces that can sometimes be chilly underfoot first thing in the morning, such as kitchens and bathrooms.

If you purchase one of our premium carpet underlay options, you can also qualify for free fitting* on your carpet order. Our premium underlay options are Spring Bond, Comfy Lux, Comfy Deluxe or Durafit and start from just £9.99m².

Carpet Underlay Options

SPRING BOND
  • 11mm thickness / 100kg/m³ Density
  • Tog Rating - 2.1
  • Made from 85% recycled sea plastic
  • Thermal Insulation
  • Suitable for all rooms and recommended for areas of heavy use

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COMFY LAY
  • 7mm thickness / 80 Density
  • Suitable for all rooms & recommended areas of light use




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COMFY DELUXE
  • Qualify for free fitting* with this underlay
  • 11mm thickness / 145 Density
  • Suitable for all rooms & recommended areas of heavy domestic & contract use

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COMFY LUX
  • Qualify for free fitting* with this underlay
  • 11mm thickness / 100 Density
  • Suitable for all rooms & recommended areas of heavy domestic use

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DURAFIT 500
  • Recommended for wheelchair use
  • 5mm Thickness / 400 kg/m³ (25lbs/cu.ft) Density
  • Suitable for all rooms & recommended areas of Heavy Domestic & Commercial use

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KING - LUXURY UNDERLAY WITH UNDERFLOOR HEATING
  • 8.30mm thickness
  • Density of 46.6 kg/m³
  • Suitable for all rooms and recommended for areas of medium use

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Laminate Underlay Options

We have added two new fantastic underlay choices for laminate flooring which can be added to your basket during the order process and will add a great deal of comfort, stability & warmth to your wood flooring.

COMFORT WHITE
  • 2mm thickness / Size 10m
  • Underlay suitable for laminate flooring

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PREMIUM SILVER UNDERLAY
  • 3mm thickness / Size 9.76m
  • Underlay suitable for laminate flooring

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