What are the Fire Ratings of SIPs?
Structural Insulated Panels (SIPs) have gained widespread popularity in modern construction due to their superior insulation, strength, and ease of installation. However, a critical consideration for their use is fire performance. This article explores the fire ratings of SIPs, focusing on Formance SIPs, and how these panels comply with safety regulations while still providing energy efficiency, structural reliability, and additional fire safety benefits due to airtight construction.
SIP Composition and Fire Resistance
SIPs typically consist of a core of Expanded Polystyrene (EPS) sandwiched between Oriented Strand Board (OSB) skins. The fire resistance of these panels is influenced by the materials used:
- Oriented Strand Board (OSB): OSB is a wood-based product, and like all timber materials, it has inherent fire resistance. The density of the OSB used in Formance panels is 560kg/m³, which meets the requirements for fire protection as Group 3 timber under the New Zealand Building Code (NZBC).
- Expanded Polystyrene (EPS) Core: The EPS core used in Formance panels is fire retardant and complies with AS1366.3:1992 Table 2 - Flame Propagation standards. Formance SIPs utilize non-HBCD (non-Hexabromocyclododecane) fire retardant EPS, reducing potential environmental harm without compromising fire safety.
Compared to metal skinned panels, SIPs have a timber composite skin which protects the EPS core for a period of time while also providing a base onto which linings, such as plasterboard, can be fixed. Formance SIPs are trimmed with solid timber; so, do not rely on folded or riveted metal connections.
Fire Performance Compliance
SIPs must meet strict building code requirements to ensure occupant safety. In New Zealand, Formance SIPs comply with the following key provisions of the New Zealand Building Code:
- Clause C3.4(a): Formance SIPs are compliant with fire safety regulations, specifically addressing how fire affects areas beyond the source. This ensures that the spread of fire is mitigated, protecting adjoining areas.
For standard residential applications, Formance SIPs alone meet the NZBC fire requirements. However, in situations requiring higher fire protection, such as for exterior walls closer than 1 meter to a property boundary, an additional fire-rated lining or cladding may be required to achieve compliance.
Production Testing
Formance panel samples are regularly tested during production to ensure the efficacy of the FR additive to the EPS. A flame is applied to the surface for 5 seconds then removed to check that the EPS self-extinguishes.
Formance SIPs Before and After Flame Testing
Airtightness and Fire Safety
One of the often-overlooked advantages of SIP homes is their inherent airtightness, which enhances fire safety. SIP houses, including those built with Formance panels, are engineered to provide a high level of airtightness, typically achieving air change rates in the range of 0.2 to 1.5 air changes per hour (ACH) at 50 pascals.
This high level of airtightness is not only beneficial for energy efficiency but also plays a critical role in fire scenarios. In a fire, flames require oxygen to grow and spread. The airtight construction of a SIP home restricts the airflow and reduces the amount of oxygen available to feed the fire, slowing its progression. As a result, fires in airtight SIP buildings are less likely to grow rapidly compared to conventional structures, which often have more gaps, cracks, and ventilation pathways that allow fire to draw in more air.
By limiting the fire's access to oxygen, the SIP structure buys valuable time for occupants to evacuate and for firefighters to control the blaze. This makes airtight SIP homes a safer option in fire emergencies, as the fire is less likely to spread quickly throughout the building.
Intertenancy Fire Protection Details
For projects that require intertenancy walls—such as multi-unit dwellings or commercial buildings—specific fire protection details are essential. Formance offers tailored solutions to meet the fire and acoustic separation requirements between tenancies. These intertenancy systems can include additional fire-rated linings or specific construction methods that provide enhanced fire resistance and soundproofing.
Formance has developed a range of tested and compliant intertenancy solutions to suit various building configurations. Whether you are designing townhouses, apartments, or other shared living spaces, we can provide the technical details required to ensure full compliance with New Zealand Building Code fire safety regulations.
If your project involves intertenancy walls or has specific fire protection needs, please reach out to the Formance team. We can supply detailed construction drawings and offer guidance to ensure that your project meets all relevant fire and acoustic requirements.
CodeMark Certification and Assurance
Formance SIPs hold a CodeMark Certificate of Conformity, which assures builders and designers that the product complies with the New Zealand Building Code (NZBC) in several critical areas, including structure, durability, and fire performance. The CodeMark certification simplifies the approval process for SIP buildings by confirming that the panels meet all necessary standards, including fire safety.
Practical Considerations
In practical construction, fire protection measures extend beyond just the materials used. Proper sealing, installation of services like electrical wiring and plumbing, and airtight construction are critical to enhancing the fire safety of a SIP-built structure. By reducing gaps and potential fire spread through airtight installation techniques, the fire performance of SIP buildings can be optimized.
Conclusion
The fire ratings of SIPs, specifically Formance SIPs, ensure compliance with stringent building codes while providing energy efficiency and structural strength. Through a combination of fire-resistant materials like OSB and fire-retardant EPS, Formance SIPs meet the demands of modern construction while ensuring safety. The inherent airtightness of SIP homes provides an added layer of fire protection by limiting the oxygen available to fuel a fire, slowing its spread, and enhancing occupant safety.
For applications requiring higher fire protection, additional fire-rated linings or claddings can be easily incorporated into the building envelope, making SIPs a versatile choice for both residential and commercial projects. With CodeMark certification and proven compliance with NZBC fire provisions, Formance SIPs offer peace of mind for builders and designers looking for a high-performance, energy-efficient, and fire-safe building solution.
If your project has specific fire safety needs, such as intertenancy details, don’t hesitate to contact the Formance team for tailored solutions and technical guidance.