Marmox Insulation Boards for Underfloor Heating Installations
Marmox insulation boards improve the performance and efficiency of electric underfloor heating by directing warmth upward into the room rather than downward into the slab — and help new homes meet NZ Building Code requirements for heated-floor insulation.
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No underfloor heating system performs at its best without the right insulation beneath it. Marmox insulation boards are placed between the concrete slab and the heating system to create a thermal barrier, directing energy upward into the room rather than letting it disperse through the slab below — which makes a real difference to your running costs over time. In fact, recent changes to the NZ Building Code now require heated floors in new homes to be insulated, and Marmox exceeds this requirement in most cases.
Marmox boards have an XPS closed-cell structure that’s completely waterproof and won’t absorb moisture or rot, making them well suited to bathrooms and other wet areas. The boards carry a compressive strength of 30 tons per square metre, keeping the floor’s structural integrity intact under load. They also offer genuine acoustic benefits, reducing footfall noise and the echo often associated with large tiled areas by up to 20 decibels.
Heat-up speed is a standout benefit: once your heating is switched on, floor tiles typically warm up in around 15–20 minutes, even over a cold concrete floor. Overall, Marmox insulation can save up to 50% of the heat that would otherwise be lost with conventional underfloor heating.
Boards are supplied at 1250mm x 600mm, in a 6mm or 10mm thickness, and are installed using a flexible tile adhesive — much like laying a large tile. Marmox is BRANZ appraised, and sourcing your insulation through Warmup means your insulation, heating element, and thermostat all come from a single supplier, giving you one point of contact for technical support across the whole installation.
Why Warmup Recommends Marmox Insulation
The efficiency of an electric underfloor heating system depends heavily on how well heat is directed toward the room above, rather than lost into the slab or subfloor below. Warmup recommends Marmox insulation boards in the following scenarios:
- Undertile heating in bathrooms — provides a waterproof, insulated substrate and improves heat-up speed
- Heated concrete slab applications — the thermal barrier directs heat upward rather than letting it disperse into the slab
- Wet area applications — the completely waterproof XPS structure suits shower floors and bathrooms
- New builds subject to NZ Building Code heated-floor insulation requirements
- Any installation where energy efficiency or acoustic performance is a priority
Complete Your Heated Floor Specification with Marmox
Warmup supplies Marmox insulation boards alongside the full Warmup underfloor heating range. Contact our New Zealand team for a complete specification covering insulation, heating, and thermostat products for your project.
Marmox Multiboard
A rigid XPS insulation board for bathroom floors and general heated-floor applications. Placed between the subfloor and the heating system, it creates a thermal barrier that directs heat energy upward.
- XPS closed-cell structure, completely waterproof, won’t absorb moisture or rot
- Compressive strength of 30 tons per square metre for a stable, load-bearing substrate
- Reduces footfall noise and tiled-area echo by up to 20 decibels
- Available in 1250mm x 600mm boards, in 6mm or 10mm thickness
- Installed with a flexible tile adhesive
- BRANZ appraised
- Compatible with Warmup heating systems
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Marmox Multiboard FAQs
A: Recent changes to the NZ Building Code require heated floors in new homes to be insulated, and Marmox exceeds this requirement in most cases. Beyond compliance, insulation significantly improves the performance of any underfloor heating system by directing heat upward into the room rather than letting it disperse into the slab, which reduces running costs and speeds up heat-up time.
A: It depends on your room’s area relative to its exterior wall length. As a guide: divide your room’s floor area by the length of its exterior (perimeter) wall. If the result is greater than 1.6, a 6mm Marmox multiboard will comply. If the result is between 1.3 and 1.6, a 10mm board is required. For example, a 3m x 3m room (9m²) with only one exterior wall (3m long) gives a ratio of 3 — well above 1.6 — so 6mm board complies. The same room with two exterior walls (6m of perimeter) gives a ratio of 1.5, requiring 10mm board. Warmup’s technical team can confirm the right specification for your specific project.
A: Yes. The XPS closed-cell structure is completely waterproof and won’t absorb moisture or rot, making Marmox boards well suited to wet area applications including shower bases and bathroom floors.
A: After switching on the heating system, floor tiles typically reach temperature in around 15–20 minutes, even over a cold concrete floor.
A: Yes. Marmox boards reduce footfall noise and the echo commonly associated with large tiled areas, by up to 20 decibels.
A: Marmox boards have a compressive strength of 30 tons per square metre, which keeps the floor’s structural integrity intact under load.
