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Manufacturer / Supplier


A1 non-combustible, MgO board

RCM Extremegreen MgO board is a high density structurally reinforced magnesium oxide based sheathing board consisting of a proprietary composition of magnesium oxide that is reinforced with multiple layers of glass fiber mesh. Magnesium oxide is a mineral based raw material.

The sheets are made in various lengths, widths and thicknesses providing a huge range of building options.

As an A1 non-combustible sheathing board Extremegreen is an excellent choice for structural timber applications.


Fire rated to EN 13501-1 class A1

Can be scribed and snapped up to 12mm

Water resistant

Environmentally friendly

Mould resistant

Contractor friendly

Gypsum and crystalline silica free

Easy to work with

Integrates with other RCM products

Standard board sizes

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

2397 x 1198mm (9mm)

2697 x 1198mm (9mm)

Other board sizes are available.


If you would like a sample please click on the ‘add sample to basket’ button at the bottom right of this page and select your samples. Once selected you can add other products also, but please make sure you click on the sample basket at the top of the website to complete your request.


RCM Extremegreen 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 a hand held circular saw with a 60+ tooth finish blade. Alternatively, RCM offer a complete fabrication service, please contact our technical department for details.

Key applications

Sheathing board

Ceilings and roofing

Internal wall lining

Tile backer board

Buildings above 18m

Flooring and sub-flooring

Suitable for the following construction types

Timber Frame

Modular / Offsite

  • Region: Europe
  • Country: United Kingdom
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