Building Codes around the world are strengthening fire regulations and the Building Code of Australia (BCA) too has amended fire provisions for safer buildings.
With evolving fire regulations, fire compliance is critical for building professionals. It is thus timely to examine fire compliance for PVC permanent formwork wall systems for load bearing internal walls.
For building classes 2 – 9, part C of BCA Volume 1 applies for fire compliance. For building classes 1 and 10, parts 2.3 and 3.7 of BCA Volume 2 apply with a simpler approach compared to BCA Volume 1. In this article, we focus on BCA Volume 1.
Nick Gouskos, Senior Engineer at AFS Systems explains, “For internal walls, numerous factors impact the fire requirements of a wall. These include internal linings, load bearing consideration, intended use of the building and type of construction required.”
Fire Resistance Level
For load bearing, internal fire resisting walls, we need to determine the Fire Resistance Level (FRL) required for the type of construction and application. BCA clause C1.9(c) requires internal load bearing walls to satisfy Specification C1.1.
Gouskos adds, “The biggest misconception we hear with PVC permanent formwork internal walls, is that PVC permanent formwork walls are not concrete walls. This is completely inaccurate. PVC formwork walls designed to AS 3600, the Australian Standard for Concrete Structures, are deemed to be concrete walls.”
Specification C1.1 requires load bearing internal walls to be constructed from concrete or masonry or fire-protected timber. As PVC permanent formwork systems are designed to AS 3600, they are inherently a concrete wall and therefore meet Specification C1.1.
Specification C1.1 details the required FRLs for all wall types, the FRL provides three performance categories in minutes of fire resistance: structure; integrity; insulation.
In a fire, an FRL 90/60/30 wall will support the imposed loads for 90 minutes; integrity prevents hot gasses or smoke passing through the wall for 60 minutes; and the wall is insulated to maintain safe temperatures on unexposed surfaces for 30 minutes.
The FRL of a wall system is determined in accordance with AS 1530.4. A full fire test is usually required; however, an assessment report may be suitable if prior testing is sufficient.
PVC permanent formwork walls when designed and constructed in accordance with AS 3600, achieve similar FRLs to reinforced concrete walls, penetrations in PVC permanent formwork walls must also comply with AS 1530.4.
Internal linings of walls require fire hazard properties to comply with BCA clause C1.10 and Specification C1.10, internal linings shall be Group 1, 2 or 3 depending on the location within the building. Group 1 materials may be used for all buildings and wall applications. Material Group numbers and smoke growth rate index (SMOGRARC) is determined in accordance with AS ISO 9705 / AS 5637.1.
The material group number and SMOGRARC are key elements to consider, as internal wall materials must not increase the risk of fire spread or adversely impact tenable conditions during occupant evacuation.
PVC permanent formwork walls in load bearing internal applications are required to be tested and assessed according to AS 1530.4 which assesses the FRL of the system (penetrations shall be compliant with AS 1530.4); and AS ISO 9705 / AS 5637.1 which determines material group number and SMOGRARC.
For internal load bearing wall applications, PVC formwork systems designed to AS 3600 and compliant with the above are Deemed to Satisfy solutions.
Load bearing internal walls
AFS Rediwall® is a PVC permanent formwork load bearing wall system, for all walls designed in accordance with AS 3600.
Comprehensive fire testing demonstrates Rediwall achieves FRLs up to 240/240/240 and Group 1 classification. Penetration treatments approved for use in concrete walls ensure Rediwall® complies with AS 1530.4.
Rediwall® is a Deemed to Satisfy solution for load bearing internal walls.
Rediwall® details are available on the AFS Specification Finder, found on the AFS website homepage.
For further information on Rediwall contact the AFS Technical Team on 1300 727 237.