DensGlass – The Gold Standard in A1 Rated Sheathing Boards, now BBA Certified.

DensGlass Sheathing is a high performance, A1 Fire Rated sheathing board that consists of a fibreglass mat with a gypsum core, designed to provide a high degree of protection from the elements in external cladding constructions.

Widely recognised by the GOLD colour, DensGlass fibreglass mat gypsum sheathing board, has an exemplary track record that spans more than 30 years in the US market place and now available in UK exclusively from Benx.


  • BS EN 13501-1 Class A1 Non-Combustible
    Consult RCM technical services of specific fire resistance to BS EN 1364-1:2015 or BS EN 1365-1:2012

  • DensGlass-Sheathing-Rush-Memorial-Hospital

Thanks to its ability to protect the building envelope against incidental moisture damage during and after construction, DensGlass  Sheathing is a preferred substrate under a wide variety of facades, such as:

  • Brick
  • Stone
  • Rainscreen Cladding

Standard Board Sizes

1200 x 2400 x 12.7mm (Longer lengths available to order, subject to minimum quantity)

Key Applications

Sheathing board to

  • Rainscreen cladding
  • Masonry façades
  • Timber cladding

Key Features

  • A1 non-combustible
  • No1 Specified Gypsum sheathing board in the US
  • 12 months exposure (when suitably sealed)
  • Lightweight, Scribe & snap, No breather membrane required
  • CE marked
  • Over 30 years in the market
  • BS EN 15283-1:2008 + A1:2009


This is a scribe and snap board.  It may be cut using the score and snap method, no power tools are required.  It can be  drilled and nailed using conventional hand tools, offering many of the properties of timber.  Screws to be installed flush to the board surface.

Suitable for the Following Construction Types

  • Lightweight Steel Frame

  • Timber Frame

  • Modular / Offsite

  • Concrete Frame

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Technical Specifications

  • Nominal Density (Oven Dry)

    750 kg/m3

  • Thermal Conductivity

    0.21 W/mK

  • Moisture Resistance

    To EN 15283-1

  • Reaction to Fire

    BS EN 13501-1 Class A1 Non Combustible

  • Biological Resistance

    Level 10 ASTM D3273

  • Surface Condition

    Fleeced - Matt

  • Durability (Life Expectancy - Minimum)

    Equal to that of the building installed to

  • Standard Board Sizes

    1200 x 2400 mm

  • Nominal Mass of Product (kg/m2)


  • Dimensional Tolerance


  • Product Testing and Certification

    • Fire Reaction Tests

      BS EN 13501-1:2007 + A1:2009 Class A1 Non-Combustible

      Consult RCM technical services of specific fire resistance to BS EN 1364-1:2015 or BS EN 1365-1:2012

  • Physical Properties

    EN 15283

  • Recommended Fixing

    • Steel Frame

      RCM FIX018 - 4.2 x 32 Tek screw

    • Timber Frame

      RCM FIX005 - 4.2 x 42 Tek screw

Ascot Road Case Study

RCM was appointed to supply its high-performance sheathing board DensGlass to a former brownfield site on Ascot Road, Watford, which will make up part of the through wall system to an RC frame with a lightweight steel frame infill


RCM Densglass can be used as an external sheathing board on structures 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.

DensGlass should be fitted with the label to the outside.

DensGlass has a rating of A1 to EN13501-1.  This is a reaction to fire classification and should not be confused with fire resistance.

No, DensGlass is not meant to be used as a permanently exposed external board. However, during construction it can be left exposed for up to twelve months with all joints treated with either RCM Tape or FR PRO Sealant. However, 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.

No, DensGlass is not meant to be used as a tile backer board.

No, DensGlass is not meant to be used as a render carrier board.

  • Minimum edge distance is 13 – 15mm
  • Maximum fixing centre is 600 mm x 300 mm
  • 27 No. fixings per 2400 mm x 1200 mm sheet when fixed in a vertical orientation.
  • 25 No. fixings per 2400 mm x 1200 mm sheet when fixed in a horizontal orientation.
  • For fixing into SFS framing RCM FIX018 4.2mm x 32mm self drilling fixing with 1000 hr anti-corrosion treatment.
  • For fixing into timber framing RCM FIX005 4.2mm x 42mm self drilling fixing with 1000 hr anti-corrosion treatment.

Construction utility knife suitable for cutting gypsum based boards.


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Densglass Video Guides

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    Densglass Key Features

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    Densglass Case Study