September 2008. Location: Rathnew, Wicklow, Republic of Ireland

Building description

The building was used as a warehouse and distribution centre, and is constructed of a steel frame with brickwork lower walls and Insulated Panels with a PIR core, approved to LPS 1181 Part 1 Grade EXT-B, installed as the upper wall cladding.

Of particular note is that there is a design gap between the drip flashing and the bottom edge of the Insulated Panels.

This gap above the drip flashing coupled with the corrugated profile of the Insulated Panels meant that the bottom of the insulating core of the Insulated Panels was exposed to any flame impingement on that part of the blockwork wall and the cladding above.

There was also a similar gap above the up-and-over door between the head flashing and the bottom edge of the Insulated Panels.

Fire

A truck had been parked across the two main “up and over” doors of the building to prevent unauthorised access during the night. Arsonists set the cab on fire and this quickly spread throughout the vehicle. The intensity of the fire and the proximity of the truck to the building meant that the panels were soon exposed to what is referred to in the investigation report as “prolonged flame impingement” during the 25 minutes before the fire brigade arrived (the isolated location meant that the alarm was not raised until 15 minutes after the fire started). At one stage there was also an explosion and a fireball projected onto the panel facing as conditions worsened.

Observations

An examination of the Insulated Panels both above and at the sides of the up and over doors showed the outer and inner skins to be intact with no deformation. In fact it was extremely difficult to prise open the outer skins to examine the inner core.

The lower edges of the Insulated Panels immediately above the up and over door on the right were prised open. The inner core had charred but had remained in-situ and there was no evidence of deformation or delamination. In addition, there was no evidence that the core of the Insulated Panels had assisted fire spread.

The proprietary wallboard at the right side of the up and over door (adjacent to where the front of the vehicle had been) had cracked as a result of heat. However, even at this location the outer and inner skins of the Insulated Panels were found to be intact with no deformation.

The lower edges of the Insulated Panels, immediately above where the proprietary wallboard had cracked with the heat, were prised open. The inner core had charred only at the edge nearest the roller-shutter door. The core had remained in-situ and there was no evidence of deformation or delamination. In addition, there was no evidence that the core of the Insulated Panels had assisted fire spread.

Comments

Key considerations were whether the panels contributed in any way to the spread of the fire and whether they helped prevent fire entering the building.

The report concluded that there were no signs of any spread of heat through the panel core, or that the panels contributed to the damage caused by the fire in any way. Furthermore, there was no delamination of the metal panel lining and the insulation core stayed in place, important points in maintaining system integrity and fire resistance.

Despite the ferocity of the fire, the inside of the premises was unaffected and business resumed as normal the next day.