What Does Tog Rating Mean for Carpet Underlay?
Like duvets, carpet underlay is rated in tog for thermal insulation — a higher tog underlay helps retain more heat in the room, which can meaningfully reduce heat loss through ground floors. Underlay tog is separate from its cushioning/support properties, so a product is generally chosen by balancing its tog rating against the right density and thickness for the carpet and traffic level above it.
The tog rating on carpet underlay – often displayed as Thermal Resistance (TR) – is a crucial factor in determining how well your floor retains heat. Essentially, it measures the material’s ability to resist heat flow. Higher tog ratings (typically ranging from 18 to 60 TR) indicate greater thermal insulation, meaning more warmth stays within the room, particularly beneficial for ground floors during colder months. However, it’s important to understand that ‘tog’ isn't a direct equivalent to a duvet rating; underlay is measured in metres squared per watt (m²/W), while duvets are assessed by their ability to trap heat.
Different underlays achieve higher tog values through varying densities and materials – for example, polyester fleece offers greater insulation than felt. When selecting an underlay, consider the room’s size and usage; a small bedroom might only need a 18-23 TR underlay, whereas a larger living room or hallway would benefit from something closer to 40 TR or more. UK shoppers often mistakenly focus solely on the highest tog rating available, neglecting to consider the density needed for their carpet's pile height and the anticipated foot traffic – too thick an underlay in a high-traffic area will compress quickly, reducing its effectiveness.
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FAQ
What does a tog rating of 18 TR mean?+
A tog rating of 18 TR indicates a relatively low level of thermal resistance. This type of underlay is generally suitable for smaller rooms with minimal foot traffic, or for use in conjunction with thinner carpets like loop pile or Berber where maximum insulation isn’t paramount.
What does a tog rating of 60 TR mean?+
A tog rating of 60 TR signifies a very high level of thermal resistance. It's ideal for larger rooms, particularly ground floor bedrooms in colder climates or areas where you want to minimise heat loss – think large living rooms or rooms with draughty windows.
How does the tog rating compare to other insulation options?+
While foam underlays offer some thermal resistance, they typically have lower tog ratings than felt or polyester fleece. For significantly higher insulation, consider specialist mineral wool underlays which can achieve much higher TR values – often exceeding 60 TR.
How do I check the tog rating of my current underlay?+
The tog rating is usually printed directly on the packaging or a label affixed to the roll. If this isn’t present, you may find the Thermal Resistance (TR) value instead; these are often measured in metres squared per watt (m²/W).
Does a thicker underlay automatically mean better insulation?+
Not necessarily. While thickness contributes to thermal resistance, it's the density and material composition that truly determine tog rating. A very thick but low-density underlay might perform worse than a thinner, denser one.
What is the relationship between underlay density and tog rating?+
Generally, higher density materials (like felt or polyester fleece) will achieve higher tog ratings at similar thicknesses compared to lower density options (such as foam). Density directly impacts the ability of the material to resist heat flow.
I’ve noticed some underlays labelled ‘high performance’ – what does this mean?+
‘High performance’ typically refers to an underlay that achieves a high tog rating (often 40 TR or above) and is designed for optimal thermal insulation, often incorporating features like zoned density or reflective layers for enhanced heat retention.
Should I always choose the highest tog rating available?+
Not necessarily. Selecting a tog rating solely based on its number can be misleading; consider your room size, usage, and carpet type – a higher tog in a small room may actually result in over-heating and increased energy bills.
What is Thermal Resistance (TR) and how does it relate to Tog?+
Thermal Resistance (TR), measured in metres squared per watt (m²/W), is the metric used to quantify an underlay’s ability to resist heat flow. A higher TR value indicates greater thermal resistance, which directly corresponds with a higher tog rating – they are effectively two sides of the same coin.
My carpet has a very thick pile - does this affect my choice of underlay?+
Yes, absolutely! Thick carpets have a larger surface area and require an underlay with a correspondingly high tog rating to provide sufficient thermal insulation. Opt for an underlay rated at least 40 TR – or higher – to avoid significant heat loss through the floor.