Klasse S-board Calcium Silicate External Sheathing Board

S-board is a high performance Calcium Silicate Board for applications that are looking for a premium A1 Non-Combustible product. This is the ultimate Passive Fire Protection board which can provide up to 240 minutes fire resistance. It is rated as a Category A board to BS EN 12467 for applications where they may be subjected to heat, high moisture and severe frost.

Hydrophobic Coating

S-board has a hydrophobic external coating meaning it can be left exposed for up to 12 months making it an excellent choice for passive fire protection in external sheathing or for roofs, floors, ceilings and internal partitions.


S-board boards are also very flexible to work with. 6mm thick S-board boards can be flexed (minimum radius 600mm) to accommodate curved surfaces. Boards will bend more easily, if bent across their long axes when they are wet.

Acoustic Performance

Acoustically tested according to ISO 10140-3. S-board provides an excellent acoustic solution when combined with SFS and stone mineral wool infill.

Durable & Robust

S-board is extremely durable when compared to all other types of boards. It can withstand all weather conditions and is highly suitable for use in places where the climate is extreme.


Suitable for lift shafts and stairwell protection applications

Can be precut to size for fire protection strips

Product Specification

Length - 2400mm

Width - 1200mm

Thicknesses - 6/9/12/16mm

Average Weights - 5.60/8.58/11.54/15.17 kg/m2

Tolerances - Length/Width - ±5mm. Thickness - ±2mm


Reaction to Fire - BS EN 13501-1 - Non-combustible Euroclass A1

Board Type - BS EN 12467 - Category A

Find out more

More about S-board

  • Download Centre  

    Download Centre

    Datasheets, brochures and more! All available from our download centre.

    Download Centre
  • NBS Source Partner  

    NBS Source Partner

    Klasse Group are partners with NBS, who write specification content and manufacturer information.

  • Projects  


    Klasse is always involved in new and exciting sheathing board projects.


It's easy to do business with us

Klasse understands your requirement for excellent service and product reliability. As a trusted supplier we provide fast quotes and rapid delivery from our UK warehouse.

We have friendly and knowledgeable experts who will help you with your external sheathing needs, every step of the way.