Flexible cement/ calcium building board, for applications that require a slightly lighter board with improved fire properties. Product offers very similar properties to cement particle board, however due to the calcium additives it offers a greater fire resistance. Fully tested to achieve a one hour through wall solution with external sheathing board properties.

As a sheathing board, it can be used behind rain screen cladding, insulated facades and cedar cladding (in this application, the use of a water resistant/ breathable membrane such as Tyvek, on to the face of the board, is recommended in line with good building practises for external cladding). CE marked and conforms to BS EN 12467.

Key applications:

  • Sheathing board on metal and timber frame.
  • OEM Application where improved strengths and density are required.
  • Fire rated flooring and roofing.
  • Fire rated walling.


  • A non-combustible classification A1.
  • Excellent water resistance properties.
  • Flexible and strong.
  • RCM's lightest sheathing board with improved workability.
  • Excellent water resistance properties.
  • One hour load bearing fire protection.
  • High impact strength.

Standard product features




  • Nominal density: 1200 kg/m³.
  • Bending strength (Modulus of Rupture): 9.8 Mpa.
  • Modulus of Elasticity (MoE): 4.0 Mpa.
  • Thermal conductivity: 0.12 W/mk.
  • Fire rating: BS 476-4 non-combustible; 1 and 2 Hour through wall fire protection tested to BS 476-22.
  • Fungus and termite attack: Highly resistant.
  • Frost resistance: Four star.
  • Front face smooth, back face textured.
  • Durability (minimum): 30 years.



Two standard sizes available, other sizes available upon request.

Recommended fixings:

4.8 x 38 mm wing tip self-drilling fixing.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-45-50/355 Fibre reinforced cement board

Product specification

An important note about specifying



RCM - Roofing and Cladding Materials Ltd


+44 (0)800 6124662

Product reference



[1200 x 1200 mm]
[1200 x 2400 mm]


[6 mm]
24 dB sound insulation.
[9 mm]
29 dB sound insulation.
[12 mm]
31 dB sound insulation.


[RCM Foil Tape]
Waterproofing seal.
[RCM Intusil]
Neutral cure sealant for use in gaps and joints.
[RCM Joint Seal]
Air tightness seal.

Manufacturer details

Units 25-26 Rosevale Road,
Parkhouse Industrial Estate West,
Staffordshire, ST5 7EF
Tel +44 (0)800 6124662
Fax +44 (0)845 1303726
NBS Plus
NBS National BIM Library