Cladding

Question 1

COMPOSITE CLADDING PANELS

Answer 1

Composite cladding panels comprise an insulation core sandwiched between two sheet skins. They are used for roof and wall cladding and usually incur higher insurance premiums due to the risk of structural collapse (when self-supporting) and combustibility in the fire resisting performance of the insulated cores.
• Polystyrene (EPS)
• Polyurethane (PUR)
• Polyisocyanurate (PIR)
• Mineral wool
EPS materials are white with small beads of solid material. Visual differentiation between PUR and PIR materials (cream or pink honeycombed foam) is difficult and laboratory analysis is required. Composite cladding panels should not be mistaken for Celutex liner panels (with a thin foil face used in place of plasterboard in a conventional industrial lining system). Look for exposed core material at services penetrations, manufacturers identification, as-built information, and panel profiles that have longer distances between profiles compared to built-up systems.
The performance of different insulated cores varies by material. EPS is a thermoplastic material that burns shrinks and melts under extreme heat, contributing to rapid fire spread through the subsequent interstitial voids. PUR starts to degrade at around 250°C whereas PIR only starts to degrade at around 400°C.
The Loss Prevention Certification Board (LPCB) evaluates the performance of composite panels in fire spread (LPS 1181) and fire resistance (1208). Generally, EPS and PUR panels will not be LPC compliant. A list of approved products and services is issued by the Loss Prevention Council website.
If composite panels are found to be non-compliant then they may be replaced. This is subject to risk assessment with insurers. With appropriate analysis of the facts a proper and informed decision can be taken as to their use and suitability in particular circumstances. Clients should be advised of the risks and existence of these materials, but with a pragmatic approach the risks can be evaluated and balanced.

Question 2

High-pressure laminates

Answer 2

Usually a blend of natural fibres and thermosetting resins manufactured under high pressures and temperatures.
Poor fixing coupled with poor drainage and ventilation behind the panel is difficult to resolve without taking the cladding off – an expensive and disruptive operation, and for which it will be difficult to recover costs in buildings under multiple ownership.
NOT PASSED BS 8414

Question 3

Insulation

Answer 3

• Polystyrene (EPS)
• Polyurethane (PUR)
• Polyisocyanurate (PIR) BETTER
• Mineral wool