Aluminium cladding and fire safety – know your fire rating
Alanod’s range of aluminium exterior surfaces are in high demand for use to create stunning visual effects on architectural structures. However, the Grenfell tower fire has shown the full devastation of what can occur when the wrong type of cladding panel is used in the wrong place.
ACM and ACP cladding
Typically, aluminium composite material (ACM) cladding consists of two skins of aluminium bonded to a polyethylene (PE), polyurethane (PUR), profiled metal or a mineral core. Although aluminium is non-combustible, during a fire the ACM panel can delaminate, exposing the core material to fire.
To make sure that tragedies such as Grenfell are avoided in the future, on 20 January 20201 Housing Secretary, Robert Jenrick, announced that a range of new measures were in discussion aimed at improving building safety standards. Amongst the proposed changes is a recommendation to ban the use of combustible cladding in buildings 11 metres tall (at present the ruling is for those 18 metres or over). Also, the independent expert advisory panel (IEAP) is supporting the view that ACM cladding that has an unmodified polyethylene core should not be used at all on residential buildings, no matter their height.
Right cladding, right place
So how can producers offer aluminium cladding that doesn’t only look stunning, but is bonded to the appropriate non-aluminium core for each application? This is where Euroclass ratings are important. The Euroclass system classifies different materials for façade cladding into non-combustible (rated as A1 and A2) and combustible (rated as B-F).
Euroclass classifications2
| Euroclass | Definition | Example materials |
|---|---|---|
| A1 | Non-combustible | Stone wool, glass wool, bricks, concrete |
| A2 | Limited combustibility | Some A1 materials with organic facings |
| B | Combustible | Some phenolic foams |
| C | Combustible | Phenolic, some polyisocyanurate (PIR) |
| D | Combustible | PIR |
| E | Combustible | Flame-retarded expanded polystyrene (EPS)/ extruded polystyrene (XPS), polyurethane (PUR) |
| F | Combustible | PUR |
| No performance determined (NPD) | Combustible |
High-rise and high-risk buildings and ACM cladding
On high-rise buildings and high-risk buildings – such as hospitals – non-combustible (A1 or A2 rated) cladding materials are recommended. Best practice is for the entire panel – so the aluminium, any lacquer or coating on it and the core – to be tested for combustibility as a unit (and contain a minimum of Class A2-s3, d2 or better materials, to meet BS EN 13501-1)3.
To be classified according to the Euroclass system, fire testing of the entire ACM panel needs to show:
- Flame spread
- Ignitability
- Smoke production
- Heat release
- Propensity for producing flaming droplets/particles
We don’t know when the final ruling on improving buildings safety standards will come into being, but one thing is for sure, we as an industry have a moral obligation to ensure that a tragedy such as Grenfell isn’t seen again because the wrong cladding core was used in the wrong place.