Waterproofing and heat flow support

Marmox Insulation Boards
No underfloor heating is complete or effective without proper Insulation to assist with both the waterproofing requirements as well directing the heat flow, which ultimately makes a big difference in reduction of your power bill. We trust Marmox Insulation boards to do just that.

Marmox is placed between the concrete slab and the heating system creating a thermal barrier, ensuring all energy is directed upwards instead of being dispersed throughout the concrete slab. It also provides excellent acoustic properties particularly in reducing footfall noise and the echo often associated with large tiled areas. These insulation boards can reduce sound by up to 20 decibels.

The XPS closed-cell structure is completely waterproof and will not absorb moisture or rot, making it ideal for tiled bathrooms. The high compressive strength of the board (30 tons/sqm) ensures the integrity of the floor is maintained.

After switching on your heating, your floor tiles will warm up in about 15-20 minutes, even on a cold concrete floor. On a wooden floor, it has a 2-degree increase every 10 minutes from startup.

Benefits of Marmox Insulation Boards

Technical specifications

Technical Properties

Density 36kg/m³
Thermal Conductivity 0.027 watt/mK
Thermal Conductivity (5 years) 0.032 watt/mK
Compressive Strength 3.0 kg/cm² (300kN/m²)
Water Absorption (Immersion) 0.02% by vol
Water Absorption (Capillary) Nil
Coefficient of Linear Expansion 30 x 10.6
Flammability B1 Class ‘0’

Board Sizes

6 100 1250 2.0 445
10 600 1250 2.2/4.4 290

Calculating requirements

Marmox multiboard significantly improves the energy efficiency of undertile heating. Recent changes to the NZ Building Code require heated floors in new homes to be insulated and in most cases Marmox exceeds this requirement.

To calculate the thickness of Marmox multiboard (required to meet the new regulations in your new home):

  • Divide the area of heated floor by the perimeter length (of the exterior walls in the room).
  • If the calculated result is greater than 1.6, then 6mm Marmox multiboard is sufficient.
  • If the calculated result is between 1.3 and 1.6, then 10mm Marmox multiboard will meet the requirement.

Example 1

Size of room: 3m x 3m
Floor area: 9 sqm
If only one wall of the room is an outside wall, the perimeter wall is 3m long.
Room area/length of perimeter wall = 9/3 = 3
As this value is greater than 1.6, 6mm Marmox multiboard will comply with the NZ Building Code.


Example 2

Size of room: 3m x 3m
Floor area: 9 sqm
If 2 walls of the room are outside walls, the perimeter walls will be 6m long
Room area/length of perimeter wall = 9/6 = 1.5
As this value is between 1.3 and 1.6, 10mm Marmox multiboard will comply with the NZ Building Code.

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Alternatively, if you want to do some more research, feel free to browse our product brochures or installation guides on our site.