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.
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Fire classification to EN 13501-1 class A1
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2400 x 1200mm (6mm, 9mm, 12mm and 15mm) Other board sizes are available
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Key Applications
- Fire rated sheathing board
- Ceilings
- Partition walling
- OEM applications for improved strength and density
- Recommended for buildings above 18m
- Ideal for Offsite Construction Regimes
Features
- Fire classification 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
Workability
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, find out more.
Y-Wall as part of a system build-up
Technical Data
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Nominal Density
1200 kg/m3
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Bending Strength
((Modulus of Rupture))9-12 MPa
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Modulus of Elasticity
((MoE))4000 N/mm2
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Thermal Conductivity
≤0.23 W/mk
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Moisture Content
≤9%
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Reaction to Fire
BS EN 13501-1 Class A1 Non-Combustible
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Biological Resistance
Highly Resistant
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Surface Condition
Front Face - Smooth
Back Face - Textured
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Durability
((Life Expectancy - Minimum))30 years
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Standard Board Sizes
2400 x 1200mm
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Thickness
((mm))6, 9, 12, 15
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Nominal Mass of Product
((kg/m²))7.3, 11.1, 14.6, 18.2
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Dimensional Tolerance
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Length
±3mm
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Width
±3mm
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Thickness
±0.5mm
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Product Testing and Certification
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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
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Physical Properties
BS EN ISO 12467
BS EN 594 Category 1
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Recommended Fixing
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Steel Frame
4.8mm x 38mm Wing tip self drilling fixing
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Timber Frame
4.2mm x 42mm Climaseal self drilling fixing
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Y-Wall FAQs
RCM Y-wall is classified as A1 non-combustible.
No, RCM Y-wall cannot be left permanently exposed.
RCM Y-wall has one smooth face and one textured face, the smooth face should be fixed outermost.
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.
If the joints are taped as soon as the boards are fitted they can be left exposed during the construction phase for up to 3 months, for up to 12 months temporary exposure we highly recommend using the RCM Joint Seal Kit.
RCM Y-wall edge distance is 12-15mm 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.
- 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.
- For fixing into SFS framing 4.8mm x 38mm self-drilling wingtip fixings suitably treated against corrosion should be used.
- For fixing into Timber framing 4.2mm x 42mm self-drilling fixings suitably treated against corrosion should be used.
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. Consult technical service for more information.
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.

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Download the Y-Wall Fact Sheet
Find out about Y-wall, a high-quality flexible calcium silicate based fibre cement building board, perfect for use as an A1 fire rated sheathing board.
Y-Wall Technical Information
- Y-Wall Air Tightness Substantiation Sheet
- Y-Wall Compressive Strength Substantiation Sheet
- Y-Wall Fire Substantiation Sheet 12mm 120 Minutes 5206
- Y-Wall Fire Substantiation Sheet 12mm 120 Minutes 5207
- Y-Wall Fire Substantiation Sheet 12mm 90 Minutes
- Y-Wall Fire Substantiation Sheet 9mm 60 Minutes
- Y-Wall Racking Resistance Substantiation Sheet
- Y-Wall Racking Resistance Substantiation Sheet 5224
- Y-Wall Wind Load Resistance Substantiation Sheet
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Y-Wall Case Study