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Multiboard (Internal)

Multiboard (Internal)

Marmox (UK) Ltd Third party certifications:
  • BBA Agrément Certificate

    BBA Agrément Certificate

    Certificate type

Tile backer board for internal use.

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+44 (0)1634 835290 www.marmox.co.uk


Suitable for use to insulate and waterproof internal walls, floors and ceilings. Thicker units can be used to construct shelving units and bathroom furniture.


Waterproof, thermally insulating tile backer board for internal use providing an effective decoupling layer between the tiled surface and the substructure. This helps to prevent tiles and grout from cracking due to horizontal movement in the floor and allows heavy weights to be safely and securely fixed to walls.

An external board is available, specified separately.

Features and benefits:

  • Lightweight.
  • Impermeable to water and acts as a moisture barrier; therefore, can be used in areas prone to moisture, such as kitchens and bathrooms.
  • Thermal insulation is unaffected by various temperatures (including freezing).
  • The cementitious surface is resistant to heat and the chemicals in the sheathing around electric underfloor heating elements, making it safe to use with these types of systems.
  • Can easily be cut in straight lines.
  • Provides enhanced tile adhesion.
  • Can be tiled over or plaster finished; therefore, acting as an alternative to laminated thermal plasterboard.
  • Load bearing capacity exceeds 100 kg/m² on walls, and 40 kg/m² on floors.
  • Boards can be aligned horizontally or vertically.
  • Does not contain any hazardous substances.
  • Manufactured in accordance with ISO 9001 Quality Management Systems and BS EN 5385-2, and CE marked to EN 13164.

Boards should be stored flat and should be covered with scrim/ reinforcing tape. For fitting instructions onto different types of substrate, consult manufacturer's literature.

General information


Extruded polystyrene (XPS)


1250 x 600 mm

2500 x 600 mm

Uniclass 2015

Pr_25_71_63_29 Extruded polystyrene (XPS) boardsPrimary


M40/27 Intermediate substrate

M40/470 Intermediate substrate

Specification data - Extruded polystyrene (XPS) boards Enhanced data


To BS EN 13164.

Third party product certification

BBA Certificate: 09/4687.

Fire performance

Euroclass E.

Compressive strength (minimum) at 10% compression

>400 kPa.

Thermal conductivity (maximum)

0.034 W/m·K


4 mm.

Thermal resistance (R-Value): 0.11 m²K/W. Board weight: 2.3 kg.

6 mm.

Thermal resistance (R-Value): 0.17 m²K/W. Board weight: 2.4 kg.

10 mm.

Thermal resistance (R-Value): 0.28 m²K/W. Board weight: 2.7 kg.

12.5 mm.

Thermal resistance (R-Value): 0.35 m²K/W. Board weight: 2.8 kg.

20 mm.

Thermal resistance (R-Value): 0.56 m²K/W. Board weight: 3.1 kg.

30 mm.

Thermal resistance (R-Value): 0.83 m²K/W. Board weight: 3.4 kg.

40 mm.

Thermal resistance (R-Value): 1.11 m²K/W. Board weight: 4 kg.

50 mm.

Thermal resistance (R-Value): 1.39 m²K/W. Board weight: 4.2 kg.

60 mm.

Thermal resistance (R-Value): 1.67 m²K/W. Board weight: 4.5 kg.

Face size (length x width)

1250 mm (±5 mm) x 600 mm (±2 mm).

2500 mm (±5 mm) x 600 mm (±2 mm).

Product Reference


Internal floors. For concrete floors. To be fixed with adhesive.


Internal floors. For plywood sheet flooring. To be fixed with adhesive or mechanically.


Internal floors. For chipboard/ oriented strand board (OSB) flooring panels. To be fixed with adhesive or mechanically.


Internal floors. For traditional floorboards. To be fixed with adhesive.


Internal floors. For raised access flooring. To be fixed with adhesive.

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Density (to DIN 53420)

36 kg/m³.

Water absorption (two day immersion, to EN 12087)

<1% by volume.

Water absorption (capillary, to DIN 53428)


Coefficient of linear expansion (to ASTM E-831)

0.07 mm/mK.

Water vapour diffusion factor (to EN 12086)


Ozone depleting potential (ODP)


Global warming potential (GWP)


Impact sound reduction (to BS EN 140-8)

21 dB.

Maximum tile loading weight

>100 kg/m² (dependent on adhesive and wall type).

Flexural strength (to ASTM C203)

>200 kPa.

Water vapour permeability (to EN 12086)

3.2 m.

Coefficient of linear expansion (to ASTM D-696)

30 x 10^-6 K^-1.


Marmox Tile backer boards and Shower bases

Marmox Tile backer boards and Shower bases

Third party certifications

  • Certificate: 09/4687

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