The facts on fire risk and exposed insulation in industrial buildings
Sponsored: Kingspan Insulation | 9 March 2017
For many developers of industrial sheds, warehouses and other no-frills properties, adding extra internal linings beyond what the building code requires is not a priority.
According to an independent technical report undertaken by professional fire engineer Benjamin Hughes-Brown from Ignis Solutions, for many of these buildings exposed insulation on internal walls and ceilings counts as a ceiling or wall lining.
That means the insulation can also under the right circumstances meet the requirements of the National Construction Code in terms of fire safety.
The NCC has different requirements for this sector, compared to multi-residential, commercial or other properties.
Hughes-Brown says part of the reason is that typically people are not sleeping in a warehouse or factory, and it is often a simple building comprising a large room or single-level space.
“In a complex building a lot of people might not be aware of their surroundings or be remote from other parts of the building,” he says. This is why fire protection rules are stricter for most other sectors.
Another design aspect of the industrial building is that fire burns well vertically, but the horizontal transport of fire is not necessarily as easy in comparison, Hughes-Brown says.
So when you have a great big long space like a warehouse or logistics depot, fire simply won’t travel as rapidly through the building as it would up the various levels of a commercial or residential multi-storey.
In industrial and warehouse buildings there is also generally more separation from other neighbouring buildings, for example by concrete truck aprons and access routes.
Hughes-Brown says that under the rules, generally the only part of an industrial property that requires fire-rated internal walls will be any office building attached to the shed, factory or warehouse.
Another difference for this sector is that insulation is not a requirement for a building to meet code. Hughes-Brown says sarking and other weather-proofing elements are also not required.
Sometimes the choice to not use insulation at all, or to leave it exposed rather than covered by a lining, is about the added costs. Owners and managers of these properties are there to operate storage, or machinery, not to sell the building on aesthetics, Hughes-Brown says.
“Cladding or making wall structures aesthetically pleasing increases cost but does not necessarily give better performance or end up making people who work in there feel better. That is not the primary function of the building.”
Any owner or developer that does decide to install insulation for either comfort or functionality is therefore going above code minimum for amenity.
When the choice to install insulation and leave it exposed is made, however, there are rules regarding what standards it needs to meet in terms of fire safety compliance.
Hughes-Brown says the point of the standards is for the insulation, when used as a lining material, to have a sufficient resistance to the spread of flame so that occupants will have sufficient time to evacuate the building safely.
“Everyone’s focused on the fire – but insulation’s primary purpose is not to be fire proof; it is there to insulate.
“Non-combustible materials don’t always give you enough thermal performance. Whilst insulation materials that have combustibles are not considered non-combustible, they typically have greater thermal performance.”
So the standard required is that insulation mitigate and not contribute to the spread of fire.
Under the current NCC provisions, insulation products used as internal linings typically need to be tested to AS ISO 9705. Hughes-Brown says this is a full scale fire test conducted in a fire test room 3.6 m long x 2.4 m wide x 2.4 m high, which is installed with the material. It tests how a material behaves in an actual full scale fire event.
The results of the testing result in a Group Number, or fire property hazard classification, between 1 and 4, which indicates the performance of the material in a fire event. The highest classification is Group 1.
Common insulation products that require testing to AS ISO 9705 to achieve a Group Number include foil-faced glasswool insulation blanket, pliable reflective insulation membrane, expanded or extruded polystyrene, insulated sandwich panels and foil-faced rigid phenolic or PIR boards.
The Group Number then dictates what other conditions need to be met for compliance.
Warehouses and industrial sheds with exposed insulation need to ensure it is Group 1, 2 or 3, depending on which part of the building the insulation is installed in and whether or not the area is sprinklered. Full details of these conditions and minimum Group Number requirements can be found in Table 3 of Specification C1.10 of the NCC BCA Volume One.
Kingspan’s Air-Cell Insuliner, for example, has a Group 2 classification. This means it can be used in most areas of buildings apart from fire-isolated exits and fire control rooms.
It also meets the NCC’s requirements around Smoke Growth Rate (SMOGRA).
The SMOGRA matters because it’s a measure of how quickly smoke would develop, which in effect means how much a person’s visibility would be obscured by the smoke – affecting the probability of a safe escape, explains Kingspan technical R&D and accreditations manager Keith Anderson.
“A high smoke growth rate would also have an impact on smoke inhalation, which is the primary cause of casualties in fires.”
A figure of less than 100m2.s-2 x 1000 is required if sprinklers are not installed, and Insuliner has a SMOGRARC = 8.5m2.s-2 x 1000.
This in combination with the Group 2 classification means a sprinkler system does not need to be installed for areas where it is used as the wall or ceiling lining.
The builder or developer will have to provide evidence that the insulation materials are compliant to either the building surveyor or certifier tasked with ensuring the project meets the NCC requirements.
“In the majority of cases evidence needs to be supplied before occupation but should be provided as part of the product tender decision,” Hughes-Brown says.
- Read the full technical bulletin here