best thermal underlay for laminate flooring

Best Thermal Underlay for Laminate Flooring in 2022 (UK Reviews & Buying Guide)

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I remember boarding out my loft by laying boards on quilt insulation. Not only did I lose lots of headroom, but I also created a bouncy castle! 

In a Hurry? Here’s our Best Thermal Underlay for Laminate Flooring in 2022:

Royale Sonic Gold 5mm - Acoustic Underlay for Wood or Laminate
  • Royale Sonic Gold Underlay - 5mm Thick - For All Wood / Laminate Flooring
  • 15sq.metres per roll (1m x 15m)
  • High Acoustic Properties

So when it came to laying laminate flooring in my lounge, I decided to investigate all the possible options properly.

This guide comes from my many hours of researching and testing the best thermal underlay for laminate flooring. Save yourself time and money by reading the following reviews and tips.


Best Thermal Underlay for Laminate Flooring – The Top 3 in 2022

Starting with our overall top pick, below are the UK’s best three thermal underlays in 2022:

1. Royale Sonic Gold Comfort Underlay

Royale Sonic Gold 5mm - Acoustic Underlay for Wood or Laminate
  • Royale Sonic Gold Underlay - 5mm Thick - For All Wood / Laminate Flooring
  • 15sq.metres per roll (1m x 15m)
  • High Acoustic Properties

Made by Newlife Contracts (Flooring) Ltd, Royale Sonic Gold is one of the top underlays for use with laminate flooring. 

This underlay is made from closed cell PE foam and includes a gold foil vapour barrier. A single roll covers an area of 15m2.

At 5mm thick, the foam evens out most subfloor imperfections and you can easily cut it with a knife or scissors.

The low thermal resistance (0.9 TOG rating) makes this an excellent choice for using over underfloor heating, allowing most of the heat to pass through. 

This underlay also has good sound deadening properties, providing a 22dB drop in noise level.

The double integrated vapour barrier offers a 200mm “over-under” overlap with the foam, giving Royale the best vapour barrier possible without taping the joints. This feature makes it ideal for use over screed or concrete floors.

ProsCons
Excellent acoustic performance, noise reduction, and impact resistanceThe gold film has little slip resistance, making it challenging to lay
The double integrated DPM provide excellent resistance to moisture rising from the substrate 
Good sound deadening properties – 22dB 

2. eXtreme Green Combat Laminate Underlay

eXtreme 3mm Green Combat Laminate Underlay with 0.8mm PE Film Thermal & Accoustic Properties (15 sqm)
  • 3mm Thick - Reduces moisture migration with 0.8mm membrane film
  • Inhibits moisture and thermal regulation
  • Exponentially reduces sound
  • Due to the low thermal resistance of the products they are ideal for use with underfloor heating systems.
  • Available for next day delivery

eXtreme (yes, that’s how they spell it) Green Combat underlay is the thinnest of the three reviewed which means it needs a substrate relatively free of undulations. 

This underlay is compressible foam on a polyethene film, and it comes in a roll that, when laid flat, measures just over 1m wide x 15m long.

The film overhangs the foam by approximately 170mm along one edge to overlap the next role, providing a sound barrier against moisture and airflow. 

However, when the water rises from the substrate or when air passes through gaps, it’s best to tape the joints.

ProsCons
With a thickness of 3mm and a low TOG rating, this underlay is best suited for laminate with underfloor heatingLess resistance to airborne sound
It’s the least expensive of the three reviewedDoesn’t handle irregularities in the substrate very well
Easy to cut and layNot suitable for flooring without underfloor heating

3. Adept Izotherm Insulating Underlay

Izotherm Insulating Underlay - Ideal for Laminate, Wood, Vinyl, Carpet, Solid Wood, Parquet, Bamboo Flooring (5.5m²)
  • Insulating Underlay Boards for Laminate, 3-Layer Floors, Wood, Vinyl, Carpet, Solid Wood, Parquet, Bamboo and more Floor Finishes
  • Izotherm Underlay Perfectly Insulates the Floor from Cold, is Easy to Install & Extremely Lightweight
  • Levels the Substrate Very Well - up to 4.6mm
  • Improves Acoustic Comfort - Very High Level of Acoustic Insulation
  • Made from 5mm XPS

Izotherm insulating underlay by Adept is a rigid XPS board, which provides excellent thermal insulation and great sound deadening properties.

As it’s rigid, Izotherm comes in a flat pack measuring 1.18m x 0.4m, containing twelve interlinked panels that, when laid out, cover a total area of just over 5.5m2.

Izotherm can take irregularities in the substrate of up to 4.6mm, so it works well on old floorboards. However, you should always try to level the surface as much as possible before putting down any underlay.

You must tape the joints to make the underlay entirely vapour resistant. We recommend doing this for all underlays if dampness is a problem.

ProsCons
Excellent insulation propertiesExpensive
Accommodates variance up to 4.6mm in the substrateNot suitable for use with underfloor heating
No need for a vapour barrierYou must tape the joints

Best Thermal Underlay for Laminate Flooring – 2022 Comparison Table

ProductTOGSound dBThickness mmCost/m2Rating out of 10
Royale Sonic Gold0.9225££9.5
eXtreme Green Combat0.67193£9.0
Adept Izotherm1.8205£££8.5

Why Use an Underlay?

laminate flooring samples and underlay

Underlay is necessary on most substrates to provide a smooth surface on which to lay the final flooring layer (e.g. laminate, carpet, tiles, etc.). 

The type of underlay depends on what flooring is going on top. For example, the underlay must be solid for small tiles to prevent any differential movement. The same applies to sheet vinyl.

Carpet usually has a thick, soft underlay to provide more comfort and to make it last longer.

Laminate flooring requires an underlay that provides a little bit of movement without turning your floor into a bouncy castle. 

Pro Tip: Always lay the underlay at a right angle to the longest wall in the room. This way, the joints in the laminate won’t coincide with the joints in the underlay.


Acoustic and Thermal Properties

Laminate is hard and transmits sound to the rooms below, so you need something that soaks up the sound.

According to Home Building & Renovating, noise is a significant stressor in the home. Whether it’s noise between rooms in a house or between flats in multi-occupancy buildings, reducing sound transfer is essential.

Laminate, being thin, also allows heat to pass through, so you need an underlay that blocks heat from escaping.


What’s the Best Type of Underlay for Your Laminate Floor?

man cutting underlay using yellow knife

Underlays come either in roll (polyethene foam) or board (XPS) form. Your final choice partly depends on what lies beneath, but more importantly, what you’re trying to achieve. 

Let’s compare the pros & cons of these two materials:


Polyethylene (PE) Foam Rolls

ProsCons
Excellent acoustic performance (high resilience) Poor thermal insulation (lower TOG value) when compared to XPS

Expanded Polystyrene (XPS) Boards

ProsCons
Excellent thermal insulation (high TOG value)Poor acoustic performance (low resilience)

Another consideration is water vapour that may be present due to moisture in the substrate. 

Concrete and screed must be completely dry before laying the laminate. You can see more on this in our articleHow Long Does Screed Flooring Take to Dry Before You Can Lay Carpet?

Water vapour can also be the result of activities below the floor. Kitchens and bathrooms generate enormous moisture, finding its way into the laminate substrate.

For this reason, manufacturers typically attach rolls of underlay to a damp proof membrane (DPM) or other types of vapour barrier. Solid boards repel moisture due to their makeup.


Other Considerations

Cost

When comparing costs between different underlay materials, check the area and evaluate the price per square metre. 

A roll typically covers 15m2, whereas a pack of boards covers only 6m2 or less.

Underfloor Heating

man installing heating red electrical cable wire on cement floor

You don’t want your underlay to block the heat from mats or pipework, so look for an underlay with a low TOG (Thermal Overall Grade) value. 

Sometimes, professionals refer to TOG as thermal resistance or R-value, and it’s easy to convert from one to the other. Just remember this: 1 TOG = R-value of 0.1 m²K/W.

Be extra careful when choosing an underlay for wet underfloor heating systems. Always check the manufacturer’s instructions.

Irregularities in the Substrate

Foam rolls tend to be better than boards at dealing with abnormalities in the substrate. 

The same resilience that makes foam rolls great for sound attenuation also makes them good at dealing with minor bumps and hollows in concrete.

Read more about laminate flooring, including how to lay it, in our laminate fitting cost guide.


Best Thermal Underlay for Laminate Flooring – Final Thoughts

There’s not much to choose between all three underlays we tested. Still, Royale Sonic wins on this occasion due to its overall sound and thermal insulation performance. 

Royale Sonic Gold 5mm - Acoustic Underlay for Wood or Laminate
  • Royale Sonic Gold Underlay - 5mm Thick - For All Wood / Laminate Flooring
  • 15sq.metres per roll (1m x 15m)
  • High Acoustic Properties

Royale also works well with underfloor heating, but you can’t beat eXtreme’s ‘Green Combat’ flooring when underfloor heating is involved. It’s cheaper too, which is why it won the number two spot on our list.

Izotherm’s a great product if you’re looking for extra thermal insulation, but it’s not as good at reducing noise. It’s also costly if you’ve got a large area to cover.