Sep 2018

The Dangers of Plastic Composite Panels

Plastic-based composite panels have been, and continue to be, a highly desirable construction material. They are energy efficient, cost effective and lightweight. But the panels are often made of highly combustible plastic materials, posing serious fire hazards. Composite panels are used extensively in the food industry, which in one 12-month period had over $600 million in losses linked mostly to these combustible elements of construction.

It’s important to remember that all plastic materials are combustible and burn with varying degrees of intensity. Automatic sprinkler installations are not always adequate to protect against a fire involving walls and ceilings made of plastic materials. With some burning plastics, for example, fire can propagate faster than standard automatic sprinklers can operate.

>Composite panels made of plastics are a source of concern for numerous reasons. The extent of the risk is not always recognized, and as a result, fire testing methods do not always adequately address the risk. Fire can spread inside combustible panels outside the reach of sprinklers or hoses, allowing fire to spread throughout an entire facility. That is why automatic sprinklers can’t adequately guard against fires involving walls and ceilings made of combustible composite panels. In addition, a building’s structure may complicate attacking a fire because of the risk of collapse.

Combustible composite panels were widely used throughout the 1970s and 1980s. Much of that construction still exists and drives the severity of present-day fire losses. Current construction should only use noncombustible types of composite panels to minimize property risk.

Composite panels generally use either foamed plastics or mineral wool as core materials. Panels using oil, oil and mineral, and plant and animal based insulation materials are all combustible. These include phenolic foam, polyurethane foam, polyisocyanurate foam, extruded polystyrene foam, expanded polystyrene foam, and multi-foils. Cellulosic fiber, sheep’s wool and cork based insulation are also combustible.

Noncombustible insulation materials include rock mineral wool, glass mineral wool, and cellular glass. Composite panels with noncombustible cores do not contribute significantly to the development of a fire. In fact, some of these panels have fire resistance ratings and can be used to form fire resisting/rated compartments within a building. And even though the combustible binders and adhesives used in constructing these panels may burn and char, the volume involved is not considered sufficient to sustain or contribute to fire spread.

Here are the characteristics of some materials commonly found in composite panels:

Table 5. Estimates of 2018 structure fires and property loss, by property use. Source: NFPA's survey of fire departments for 2018 fire experience.
  1. Expanded Polystyrene (EPS)
    • High heat release with toxic smoke
    • Fire can rapidly spread internally within the panels
    • Still in use
    • Cheap, inexpensive, easy to use
img 1
  1. Polyurethane (PUR)
    • Takes longer to become involved in a fire
    • Heat release rate equals or can exceed that of EPS (polystyrene)
    • Yellow, grainy closed cell texture
    • As “unacceptable” as EPS
img 2
  1. Polyisocyanurate (PIR)
    • Thermosetting – forms a strong char, preventing flame spread within the panel
    • <FM> and LPCB (Loss Prevention Certification Board) approved panels available
    • Wall, facade, internal and roofing panels all available with various <FM> and LPCB approval ratings
    • Currently the most popular panel for new construction where insurance industry approved panels are specified
hand feeling fire heat of fire on opposite side of a wall.
  1. Rockwool
    • Up to 240-minute fire rating available
    • Panels can be porous, allowing water ingress in wet areas
    • Poor walk-on properties allow delamination, leading to ingress of water and condensate from roof void to ceiling
    • Heavy – direct replacement for combustible panels at existing sites may not be possible. New sites may require more steelwork

Risk Logic advises that construction projects never use EPS, PUR or other combustible construction, but use only LPCB or approved panels installed strictly in accordance with the specific panel approval listing conditions and manufacturer’s installation instructions / guidance. In addition, careful management of existing combustible construction is essential. Contact Risk Logic with any questions you may have regarding property loss prevention for facilities using plastic composite panels.