Helping heating systems run smarter and more efficiently, Marmox Multiboards combine thermal insulation, waterproofing, and strength in a single solution for warm, comfortable and energy-conscious floors
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Marmox Multiboards have become an essential component in underfloor heating installations across the UK, offering a practical and energy-efficient way to improve system performance and reduce running costs.
Designed to sit beneath electric or wet underfloor heating systems, the boards create a thermal barrier that keeps more warmth where it belongs—in the home.
Constructed from dense extruded polystyrene (XPS) with a waterproof, cement-based coating on both sides, Marmox Multiboards combine insulation, strength and moisture resistance in one easy-to-use product.
This combination is particularly valuable in older or poorly insulated buildings, where heat loss into the subfloor can significantly reduce system efficiency.
With a thermal conductivity of just 0.034 W/mK, the boards help achieve faster warm-up times and lower energy consumption. Available in a range of thicknesses, they’re suitable for concrete or timber floors in both new-build and refurbishment projects. Importantly, their slim profile allows installers to improve performance without significantly altering floor height—an important factor in retrofit scenarios.
The cementitious surface also provides an ideal base for tiling. It bonds securely with adhesives and levelling compounds, making it particularly well-suited to large-format tiles and natural stone finishes.
In bathrooms, wet rooms and utility spaces, the boards offer an additional layer of waterproofing to protect subfloors from moisture ingress and related damage.
Multiboards are straightforward to cut, handle and install, and can be fixed using either tile adhesive or mechanical fixings depending on the subfloor type. Once in place, heating elements are applied directly on top, ready for the final floor covering. This simple process supports faster project delivery and greater consistency in thermal performance.
Beyond their insulation value, the boards help installers meet modern standards for comfort and energy efficiency. With energy costs on the rise, homeowners are increasingly aware of the need to get the most from their heating systems—and Multiboards play a key role in achieving that.
Marmox has designed the boards with usability in mind, offering practical benefits not only to installers but also to developers and homeowners looking to futureproof properties. Their dual-purpose design simplifies project planning and ensures thermal improvements without adding unnecessary build complexity.
Whether specified as part of a new development or installed during a renovation, Marmox Multiboards represent a practical upgrade that improves comfort, safeguards building fabric, and supports long-term sustainability. Their combination of thermal performance, waterproofing and build quality continues to make them a preferred choice across the industry.
