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GBE Bird Box Back Panel Q+A

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GBE Bird Box Back Panel Q+A

Information 1 Specification:


Background 1

  • We have a potential customer for our product and they do not want anything inflammable in their wall.

Requirement 1

  • Project requirement: A1 but I do not know what A1 means.
  • Can you please help me answer this request intelligently.

Answer 1

  • Supplier information:
  • I am not familiar with the “A1” classification, which by Googling I believe is a “not combustible classification”.
  • As far as I can see Palram do not claim an A1 classification anywhere in their literature.
  • If you are referring to specification EN 13501,
  • I think the answer is that Palram’s Palight is not A1

Response 1

  • Thank you for the links most helpful
  • This feels like an over the top knee-jerk reaction post-Grenfell by the designer
  • Does this apply to an over 18 m high building?
  • PII Insurers may also be applying pressure beyond building regulations
  • And Customers may also be having their say protecting their building as well as occupants
  • Designers may also be making their choices
  • This may also be a decision based on environmental grounds
  • In which case there is no argument

Information 2

CEN standard:

EN 13501-1:2002 Fire classification of construction products

EN 13501-1
England W & NI Scotland Materials
Euro-class A1

Not contributing to a fire

Non-combustible Non-combustible Stone wool, glass wool, Foamglas (no plastics)
Euro-class A2 Limited combustible Non-combustible Higher density & higher binder % or faced Stone/Glass wool

‘Self-extinguishing’ is not referred to in EN 13501-1 but may relate to Ignitibility (a different standard)

Plastics are basically fuel in a fire

Plastic based boards are not suitable with this project requirement of A1

Aluminium foil faced plastics insulation can also be A1 but if the foil face is not present at any part then the plastics insulation become fuel

Rockpanel FS-X (compressed Rockwool 8 mm) is only Euro-Class A2 (again not suitable for project requirement)

Answer 2

Material level consideration:

I would suggest that Swift box the product would need a non-combustible back panel

Subject to meeting the A1 rating some materials that may meet the A1 requirement:

  • Mineral boards, Calcium Silicate, Cement boards, Plasterboard

Answer 3
Product level consideration:

  • An front access hole for swifts will be minimum 33 mm diameter
  • Fire can pass through a gap of 25 mm (Exover/Rockwool test evidence)
  • Fire on the façade will stick (with viscosity) to the surface, remaining within the Boundary layer
    • Reach the front access hole and enter the box
    • Once inside the box the Class 1 surface spread of flame of all surfaces
    • Flames will not travel but there is nowhere to go in a small box
    • Then if the fire continues to burn and enter, the back panel will combust
    • Flames may then enter the cavity of a masonry cavity wall

Answer 4
Project level consideration:

  • If the wall is masonry cavity wall it may be uninsulated, partially or fully filled with insulation
  • Partially filled cavities will normally be 50 mm wide
    • Some full fill insulations create a >5 mm cavity to the inner face of the outer leaf for rainwater passage
  • The fire entering from the cavity from the swift box
    • Can enter a 50 mm uninsulated or partially insulated cavity and move freely
    • Can pass through 25 mm cavity
    • Cannot pass through 5 mm cavity
  • If the cavity is faced by a plastic insulation the insulation could ignite and combust
  • If foil faced the insulation is unlikely to ignite and not combust, and not readily spread flames
    • except at any points where the foil is damaged, missing and also at the joints
    • Then the insulation core is exposed and it will probably ignite and combust
    • The plastics core will become fuel and the ventilated cavity will continue to support combustion
  • If the project has already excluded all combustible materials from the cavity
    • Not using expanded polystyrene, extruded polystyrene, PIR or other plastic insulation
    • If the project has already excluded combustible materials with foil faces
    • Then the cavity filled with non combustible materials should not become a route for passage
      • g. Stone wool thermal insulation
    • But a cavity with no insulation may permit the flame to progress
      • But low surface spread of flame surfaces of the cavity will limit the spread,
      • As long as there is no combustible materials in the cavity no problems should occur
    • Embedded timbers, Wall plates and joist ends could be a relatively small problem
      • Protected by charring and preventing further combustion
    • Plastic or Bitumen based Cavity tray DPCs, PVC cavity closers, GRP lintels, etc.
      • could become a fuel and develop into a problem.

Conclusion 1

  • Above is my interpretation and response, I hope this throws some light on it,
  • Basically the back panel does not comply with the project requirement of A1 at material level
  • But at project level there is low risk if they got rid of all combustible materials from the building.
  • There may be other PVC or plastics components in the wall already.
  • But the designer should consider the size of the panel in the wall and its relationship to any other combustible components in the wall.

Information 2

  • Thank you for your comprehensive answer.
  • I have sent all of the supplier information to the potential customer to see what they come back with.
  • If they say no to Palight:
    • I might suggest this as a material
    • Fibre cement board by Cembrit
    • Although it would be more expensive in terms of labour,
    • It only comes in planks 150mm wide.
    • I doubt we can cut it with a laser cutter, but we do have a very efficient tile cutter that could do it.
  • I just hope common sense reigns.
  • Earlier today, I tried and failed to set light to a small piece of Palight
    • a lot of smoke and soot, but no flame.

Response 2

  • Fibre cement sounds right.
  • The lack if flame is the non-ignitability characteristic that is not considered by that EN

Information 3

  • Thanks – we made our original prototypes out of cement fibre-board.
  • They take a bit more labour.

© GBE NGS ASWS Brian Murphy aka BrianSpecMan
20th August 2019 – 21st August 2019

GBE Bird Box Back Panel Q+A
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20th August 2019 – 21st August 2019

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