Do You Need Insulation Boards for Underfloor Heating?

Do You Need Insulation Boards for Underfloor Heating? (UK Guide 2026)

If you're installing underfloor heating, one of the most common questions is:

👉 Do you actually need insulation boards?

The short answer is yes — in most cases, they make a huge difference to performance, efficiency, and running costs.

What Do Insulation Boards Actually Do?

Insulation boards are installed beneath your underfloor heating system. Their job is to stop heat from escaping downward into the subfloor.

Without insulation, a significant amount of heat is lost — especially on concrete floors.

👉 With insulation, heat is directed upwards into the room where you actually want it.

What Happens If You Don’t Use Insulation?

Skipping insulation boards is one of the most common mistakes.

• Slower heat-up times
• More energy wasted
• Higher running costs
• Reduced overall performance

In some cases, the system may still work — but it will take longer to heat and be less efficient.

Benefits of Using Insulation Boards

• Faster heat-up: Floors warm up much quicker
• Better efficiency: Less heat lost into the subfloor
• Lower running costs: Less energy needed to heat the room
• Improved comfort: More consistent heat across the floor

👉 In most installations, insulation boards pay for themselves over time.

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When Are Insulation Boards Most Important?

Insulation boards are especially important in the following situations:

• Concrete subfloors
• Ground floors
• Rooms with high heat loss
• Bathrooms and kitchens

These areas lose heat more quickly, so insulation has a bigger impact.

Example: Bathroom Installation

Without insulation, the system will take longer to heat up and use more energy.

With insulation, heat is directed upwards, making the system much more effective.

Do Insulation Boards Increase Floor Height?

Yes — but only slightly.

Most insulation boards are available in slim profiles (typically 6–10mm), so the increase in floor height is minimal.

In most cases, the performance benefits far outweigh the small increase in height.

Are Insulation Boards Always Required?

Technically, no — but they are strongly recommended in almost all installations.

You might skip insulation if:

• The floor is already well insulated
• You're installing over an insulated substrate

👉 However, most installers still use insulation boards to maximise performance.

Common Mistakes to Avoid

• Skipping insulation to save money
• Using the wrong thickness
• Installing directly onto cold concrete

These mistakes reduce efficiency and can lead to higher running costs.

Not Sure Which Insulation You Need?

Ready to Improve Your System?

Browse our range of insulation boards for underfloor heating and get the best performance from your system.