• Choosing the best underlay for underfloor heating

Underlays for underfloor heating

Nothing feels quite so luxurious as an underfloor heating system – the only method of home heating that puts you in direct contact with your source of warmth. It’s an increasingly popular option as an energy efficient alternative to traditional radiators, especially as it comfortably warms rooms from the ground up.

Can I use an underlay with underfloor heating?

The good news is, that in many cases, you can. Which means you will receive all the benefits that underlay brings: greater comfort underfoot, prolonged life of your flooring and reduced sound transmission.

Which underfloor heating systems work best with underlay?

If you have a wet or forced air underfloor heating system, you will need a special underlay to ensure it works as efficiently as possible. We do not recommend you use an underlay with electric (or dry) types of underfloor heating systems.

Underfloor heating underlay is specifically designed to have a low tog rating so heat can flow easily into the room. We strongly recommend that an underlay with a maximum of 0.8tog is used. If you use a standard underlay, especially one made from PU foam, it will act more like a barrier and prevent the warmth from an underfloor heating system rising into the room, making it more expensive to run in the long term. Standard underlays are also not designed to withstand heat and may crumble and degrade over time, ultimately costing you effort and money to replace.

To ensure you get the best results no matter what floor coverings you decide to use, Interfloor have developed a variety of underlays for underfloor heating which will offer optimum performance.

Underfloor heating type
Heatflow Wood & Laminate
Heatflow Carpet
Embedded water pipes in floor/floor screed
Amorphous ribbon heating mats on top of structural floor
Electric cable buried in screed or within suspended timber floor
Check with manufacturer of heating system
Check with manufacturer of heating system
Electric heating mats on top of structural floor

What is a tog rating?

When choosing underlay for underfloor heating, the tog rating is something you need to consider. It’s the thermal resistance of an underlay. The lower the tog rating of a product, the lower its thermal resistance is. Having a low thermal resistance means that more warmth can pass through the underfloor heating underlay and into your home. Although a rating of less than 1.0 is normally sufficient, the lower the tog value of the underlay, the better.

If you are looking for an underlay for underfloor heating in combination with a carpet, this is quite a specialist requirement. We would suggest a target tog should be 0.8 or less. If you are wanting an underlay for hard flooring, then a tog rating of less than 0.4 is ideal.

We do recommend to always check with the system manufacturer for their maximum recommended tog for the total floorcoverings, which is the tog of the underlay plus the to rating of the floor covering, as some manufacturers may quote different values.

Can underfloor heating go under laminate?

Yes, it can – although you will need to make sure you select an appropriate underlay. We recommend Duralay Heatflow Wood & Laminate as the best laminate underlay for underfloor heating.

Heatflow Wood & Laminate offers the following benefits:

  • Exceedingly durable
  • Noise reduction of 21 dB
  • Low tog rating of 0.35 tog
  • Works with engineered and laminate floors

Can you have carpet with underfloor heating?

It’s a common misconception that you can’t pair carpet with an underfloor heating system. As long as you select the right products, you can enjoy warm floors and soft carpeting for a feeling of total luxury. The best underfloor heating underlay for carpet is Heatflow Carpet, due to its following characteristics:
  • Excellent thermal conductor
  • Tog value of 0.80
  • A good balance of tog and comfort
  • Protects against wear and reduces noise
Our Tredaire King underlay for underfloor heating and Defender products are also excellent alternatives.

Finding the right solution for your project

We have categorised our underfloor heating underlays into carpet and hard floor product sections below, so you can easily select the right underlay for you. If you’re still unsure, or you’d like a little more information, please get in touch with our team.

Construction, renovation & sports flooring

Specialist solutions for refurbishments and sports flooring

Rubber crumb cradles are adaptive, eco-friendly and used extensively in new build, refurbishment and conversion projects. They are also the ideal solution for bringing underfloor heating into sports halls, gyms and leisure centres. This versatile system creates a void where the underfloor heating, services and insulation are laid beneath. The batten and cradle system also has the additional benefit of greatly reducing sound transmission, whilst also compensating for uneven subfloors.

Learn more here