The caloric value of building materials has a major effect on their performance during fire. Compare the PCS values of the most commonly used solutions for facade cladding and find out what this means for the fire safety of your building.
ACP and ACM: what are the risks in fire safety?
ACP (Aluminium Composite Panels) or ACM (Aluminium Composite Materials) are flat panels consisting of two thin coil-coated aluminium sheets, bonded to a non-aluminium core. The most common ACP core nowadays for facade application is the mineral filled polymer core with fire retardants. These materials are combustible and have a reasonable reaction to fire performance. ACMs with the highly flammable polyethylene core or polyurethane core without fire retardants have a very poor reaction to fire performance. In the aftermath of the Grenfell fire, they have been withdrawn or even forbidden for ventilated façade application in many countries. However, this composition is still available on the market. In case of fire, these types of panels can delaminate and expose this core, with all its consequences. The issue with an exposed core is even becoming bigger when profiled into so-called cassettes (a common application of ACPs). This type of ACM should be avoided at all times for ventilated façade application. Next to the combustible mineral filled polymer core with fire retardants, most major manufacturers of ACMs also offer products with a mineral filled non-combustible core which leads to a lower calorific value.
How is High Pressure Laminate (HPL) made?
HPL (High Pressure Laminate) panels are made of resin impregnated cellulose layers that are cured under heat and high pressure. Among these various layers are ones with overlay paper, decorative paper and Kraft paper. HPL panels consist of about 60-70% paper and about 30-40% thermosetting resins. All these materials are combustible by nature and therefore have a poor reaction to fire performance. This performance can be improved by adding flame retardants, but the calorific content of these materials remains high. High Pressure Laminate (HPL) panels contain lots of organic material that will ignite when heated. This makes it combustible and explains why the manufacturers choose to use fire retardants in these products. These are needed in order to pass an SBI test. However, to be sure of a totally fire safe solution, it is strongly advised to use non-combustible panels and do not risk the somewhat dodgy performance of panels that include fire retardants to ‘mask’ their high calorific value.
Fibre cement and fire safety
Fibre cement is a composite material, made of cement reinforced with cellulose fibres. Fibre cement boards can be pre-painted or pre-stained or this can be done after installation. The fire behaviour of fibre cement boards is very good, because of their low calorific content.
Stone wool fibres: fire resilient by nature
Rockpanel boards are made of highly compressed stone wool fibres from the natural material basalt (volcanic rock). The panels are finished with a decorative coating. For the binding of the fibres small amounts of thermosetting resin is used, creating a panel with a low calorific content and very good reaction to fire performance.