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A1 non-combustible, BBA certified fibre cement building board

RCM Y-wall is a high-quality flexible calcium silicate based fibre cement building board, perfect for use as a fire rated sheathing board.  Offering excellent fire properties as well as high levels of dimensional stability, Y-wall is an exceptional board for use in multiple applications.

Y-wall is used primarily as a fire rated sheathing board or building board. Used extensively on both steel frame and timber frame structures, Y-wall is used behind all types of facade solutions, as well in ceilings offering a non-combustible classification.

Y-wall is ideal for modular construction methods.


  • Fire rated to EN 13501-1 class A1
  • BBA approved
  • Flexible and strong
  • Excellent water resistance
  • Easy to use
  • High levels of dimensional stability
  • Integrates with other RCM products

Standard board sizes

2400 x 1200mm (6mm, 9mm, 12mm and 15mm)

Other board sizes are available.


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RCM Y-wall can be cut, drilled and nailed using conventional hand tools; offering many of the properties of timber.

For cutting the product in any volume, we recommend the use of an RCM poly crystalline diamond Dart Blade to avoid excessive wear on other blades. Alternatively, RCM offer a complete fabrication service, please contact our technical department for details.

Key applications

  • Fire rated sheathing board
  • Ceilings
  • Partition walling
  • OEM applications for improved strength and density
  • Recommended for buildings above 18m

Suitable for the following construction types

  • Lightweight Steel Frame
  • Timber Frame
  • Modular / Offsite

Technical Data

  • 1200 kg/m3
  • 12 N/mm2
  • 4000 N/mm2
  • ≤0.30 W/mk
  • ≤9%
  • BS EN 13501-1 Class A1 Non-Combustible
  • Highly Resistant
  • Front Face - Smooth
  • Back Face - Textured
  • 30 years
  • 2400 x 1200mm
  • 6 9 12 15
  • 7.3 11.1 14.6 18.2
    • Length
    • Width
    • Thickness
    • Fire Reaction Tests
      BS EN 13501-1 Class A1
    • BS EN ISO 1716:2010
    • BS EN ISO 1182:2010
    • BS 476 Part 4
    • BS 476 part 21 and BS 476 part 22 fire rated through wall solutions
    • Physical Properties
      BS EN ISO 12467
    • BS EN 594 Category 1
    • BS EN ISO 1015-11
    • BS EN ISO 1062-1
    • Steel Frame
      4.8mm x 38mm Wing tip self drilling fixing
    • Timber Frame
      4.2mm x 42mm Climaseal self drilling fixing


What applications can RCM Y-wall be used in?

  • RCM Y-wall can be used as an external sheathing board on all structure where a fire rating is required including those greater than 18m in height, where a structure is over 18m in height RCM Y-wall should be used from ground level all the way up the structure.

What is the fire rating of RCM Ywall?

  • RCM Y-wall is rated as A1 non-combustible.

Can RCM Y-wall be used as a permanently exposed external board?

  • No, RCM Y-wall cannot be left permanently exposed.

Which way round should RCM Y-wall be fitted?

  • RCM Y-wall has one smooth face and one textured face, the smooth face should be fixed outermost.

What should be used to tape the board to board joints?

  • RCM Dafa tape should be applied to all board to board joints as soon as possible after fixing the boards, unless an airtight seal is required to the external face of the sheathing board, for an airtight seal then the RCM Joint Seal system should be used.

During the construction phase, how long can RCM Y-wall be left exposed?

  • If the joints are taped using RCM Dafa tape as soon as the boards are fitted they can be left exposed during the construction phase for twelve months.

What are the fixing edge distance and maximum fixing centres for RCM Y-wall?

  • RCM Y-wall edge distance is 15mm except at the board corners where fixings should be moved up or down to achieve 50mm. Fixings should be fixed using a maximum 600mm x 300mm grid pattern.

How many fixings are required for RCM Ywall?

  • 27 No. fixings per 2400mm x 1200mm sheet when fixed in a vertical orientation.
  • 25 No. fixings per 2400mm x 1200mm sheet when fixed in a horizontal orientation.

What type of fixings should be used?

Can RCM Y-wall be fixed to a radius?

  • RCM Y-wall should not be fixed to a radius but should be cut into vertical strips and fixed to form the curve from a series of flat panels.

What blade is suitable for cutting RCM Y-wall?

  • RCM can supply Poly Crystalline Diamond (PCD) blades suitable for cutting RCM Y-wall in a range of diameter and bore sizes, please contact RCM Technical department for further information.




Case Studies

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