Home > Companies > Marmox (UK) Ltd > Multiboard (External)

Waterproof, thermally insulating tile backer board for external use. An internal board is available, specified separately.

Features and benefits:

  • Lightweight.
  • Dimensionally and structurally stable in all weather conditions.
  • Resistant to freeze-thaw damage.
  • Provides an effective decoupling layer between the tiled surface and the substructure.
  • The surface allows heavy weights to be safely and securely fixed to walls.
  • Impermeable to water, and acts as a moisture barrier.
  • Thermal insulation is unaffected by various temperatures.
  • The cementitious surface is resistant to heat and chemicals.
  • Can easily be cut in straight lines.
  • Provides enhanced tile adhesion.
  • Load bearing capacity exceeds 100 kg/m².
  • 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.


Carrier element for fixing ceramic and stone tiling and brick slips to external walls. Provides thermal insulating and waterproofing.

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

Related literature

The following content references this product:

Standard product features


Extruded polystyrene (XPS), covered on both sides with fibreglass mesh, encased in a 0.75 mm layer of polymer modified concrete which permanently bonds to the mesh polystyrene.

Technical characteristics:

- Foam component:

  • Density (to DIN 53420): 36 kg/m³.
  • Thermal conductivity (K-value, to EN 13164): 0.027–0.034 W/m·K.
  • Compressive strength (10% deflection, to EN 826): 300 kN/m².
  • Water absorption (2 day immersion, to EN 12087): <1% by volume.
  • Water absorption (capillary, to DIN 53428): 0.
  • Coefficient of linear expansion (to ASTM E-831): 0.07 mm/mK.
  • Water vapour diffusion factor (to EN 12086): 110–225.
  • Fire behaviour (to EN 13501): Euroclass E.
  • Ozone depleting potential (ODP): 0.
  • Global warming potential (GWP): <0.29.

- Multiboard (generally):

  • Declared thermal conductivity after five years (to BS EN 13164): 0.036 W/m·K.
  • Compressive strength (10% compression, to EN 826): >400 kPa.
  • 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.
  • Fire propagation (to BS 476-6): 8.1, Class 0.
  • Spread of flame (to BS 476-7): 1, Class 0.
  • Impact sound reduction (to BS EN 140-8): 21 dB.
  • Working temperature range: -50°C to 75°C.


Product reference:

Subsequent numbers are appropriate board thicknesses (e.g. EW1-12-60 relates to board thickness 12–60 mm). Please ensure thickness selected corresponds with product reference chosen. View manufacturer's literature for more information on specific product references.


Allow for dimensional tolerances of ±1 mm.

NBS Specification

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This product is associated with the following NBS Create clause:
45-45-65/410 Extruded polystyrene (XPS) board

NBS Specification

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This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Marmox (UK) Ltd


+44 (0)1634 835290

Product reference

External walls. For concrete block and brick substrates (flat). To be fixed with adhesive.
External walls. For aircrete block walls. To be fixed with adhesive or mechanically.
External walls. For rendered walls. To be fixed with adhesive or mechanically.
External walls. For intermediate plywood layers on timber/ metal frames. To be mechanically fixed.

Size (l x w)

[1250 mm (±5 mm) x 600 mm (±2 mm)]
[2500 mm (±5 mm) x 600 mm (±2 mm)]


[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.

Manufacturer details

Caxton House,
101-103 Hopewell Drive,
Kent, ME5 7NP
Tel +44 (0)1634 835290
Fax +44 (0)1634 835299
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