Description
Maximise Underfloor Heating Efficiency with Minimal Build-Up
ThermoSphere Concrete Insulation Board is a lightweight, uncoated thermal insulation board designed to sit beneath electric underfloor heating systems installed into concrete and screed floors. By reducing downward heat loss into the substrate, it directs more warmth up into the room, improving the efficiency of the heating system by up to 50% while keeping the overall floor build-up height to a minimum — ideal for both new-build and refurbishment projects.
Key Benefits
- Boosts underfloor heating efficiency by reducing heat loss into concrete and screed substrates
- Minimal build-up height, making it ideal for tight refurbishment thresholds
- 100% moisture and rot proof, suitable for bathrooms and wetrooms
- Lightweight, easy to cut and work with on site
Applications
Designed for professional installers, electricians and tilers fitting electric underfloor heating cable, mesh or foil systems beneath tile, screed or floating floor finishes. Suitable for use in kitchens, bathrooms, wetrooms and living spaces where a heated floor is being installed over a concrete or screed subfloor. Available in two thicknesses to suit different insulation and build-up requirements.
Performance & Features
Manufactured from a rigid, closed-cell foam insulation board with excellent compressive strength, ThermoSphere Concrete Insulation Board withstands foot traffic and screed loading during installation without compressing. Its low thermal conductivity and low water absorption make it a reliable insulating layer beneath tiled, screeded or floating heated floors, while remaining rot and moisture proof for long-term performance in wet areas.
Compatibility
Compatible with all ThermoSphere electric underfloor heating cable, mesh and foil systems, and suitable for use ahead of tiling with flexible tile adhesive. Cuts easily with a sharp trade knife to fit around pipework, thresholds and awkward room shapes.
ThermoSphere is manufactured in Marden, Kent, and backed by Millcot's trade support — buy with confidence from a specialist UK underfloor heating and tiling supplier.
Key Features
- Reduces heat loss into concrete and screed substrates
- Boosts underfloor heating efficiency by up to 50%
- Minimal build-up height — ideal for refurbishment
- 100% moisture and rot proof
- Lightweight and easy to cut and work with
- Available in 6mm and 10.5mm thicknesses
Technical Specifications
- Board size: L 1200 x W 600mm (0.72m² per board)
- Thickness: 6mm or 10.5mm
- U-value: 3.04 W/m²K (6mm) / 2.27 W/m²K (10.5mm)
- Compressive strength: 300kPa
- Thermal conductivity: 0.033 W/mK
- Water absorption: 0.6%
- Density (foam): 36kg/m³
- Temperature range: -50°C to +75°C
- Fire performance: Euro Class E (EN13501)
- Impact sound reduction: 19dB (tested to BS EN 10140-3, based on 6mm thickness)
- Country of origin: UK
What's Included
Each unit supplied is a single insulation board measuring 1200 x 600mm, in your selected thickness (6mm or 10.5mm). Boards are supplied uncoated and ready to cut to size on site.
Downloads
FAQs
Which thickness should I choose?
The 6mm board suits refurbishment projects where floor build-up height is limited, while the 10.5mm board provides a lower U-value and greater insulation performance where height allows.
Is this board suitable for use with tile adhesive?
Yes, once the underfloor heating element is installed over the board, tile directly using a flexible (S1) tile adhesive.
Can it be used in bathrooms and wetrooms?
Yes, it's 100% moisture and rot proof, making it suitable for bathroom, wetroom and kitchen installations.
Does it work with all ThermoSphere heating systems?
Yes, it's compatible with ThermoSphere electric underfloor heating cable, mesh and foil systems.
How do I cut the board to fit my room?
The board is lightweight and can be cut to size with a sharp trade knife or saw to fit around pipework and room shapes.
What's the difference between this and a tile backer board?
This is an uncoated thermal insulation board designed specifically to sit beneath underfloor heating elements to reduce heat loss — it is not a waterproof tile backer board.