Recent media attention on the use of non-compliant building products has sharpened the focus on building professionals to ensure their projects are accepted by certifiers and surveyors alike.
Part of this increased scrutiny means verifying all external and internal wall systems comply with the relevant Performance Provisions of Volume 1 or 2 of the Building Code of Australia (BCA).
Permanent formwork wall systems have the same BCA provisions as conventional wall systems. For external walls, this includes factors such as structure, weatherproofing and thermal resistance, and might also include fire performance. Internal walls require adherence to the provisions for structure, as well as fire and acoustic performance.
Although these provisions are detailed within the building code, misconceptions still remain about permanent formwork systems, especially PVC-based formwork, explained Nick Gouskos, Senior Technical Engineer at AFS Systems, a CSR Limited Company.
“These mostly relate to spread of fire and combustibility performance,” he added.
The reality for PVC formwork systems is that PVC used for most permanent formwork systems contain flame retardants within the PVC mix. This helps improve its behaviour when exposed to fire, as the PVC does not propagate fire spread and self-extinguishes when the fire source is removed.
“Another misconception is that when PVC is exposed to fire the smoke is excessive,” Gouskos said.
However, successful testing in accordance with AS5637.1 (AS/ISO9705) and AS1530.3 has proven that smoke developed when PVC permanent formwork systems are exposed to fire meet the ‘Deem-to-Satisfy’ provisions of the BCA.
“PVC based formwork systems are some of the most rigorously tested products, especially with respect to fire performance,” Gouskos added.
Five important factors
Typically, PVC permanent formwork systems must be compliant with the following pillars of the BCA:
1. Structural
PVC formwork systems provide load bearing and non-load bearing reinforced concrete walls to buildings. Concrete walls must be designed in accordance with AS3600.
2. Fire
PVC formwork systems are tested and assessed in accordance with a wide range of fire tests, which can include:
- AS5113: determines flame spread over an external wall;
- 3: confirms ignitability, flame propagation, heat and smoke release indices;
- 4: assesses the Fire Resistance Level (FRL) of the system; and
- AS ISO 9705/ AS5637.1: determines material group number and Smoke Growth Rate (SMOGRA).
3. Weatherproofing
External wall systems are subject to water penetration and weather tightness assessment to confirm compliance with BCA (Volume 1) weatherproofing Performance Requirement FP1.4.
4. Acoustics
Concrete provides acoustic performance such that wall systems greater than 150mm thickness achieve the airborne sound reduction targets of the BCA. Separate stud walls or resilient mounted furring channels may be used to achieve the impact sound rating requirements.
5. Thermal
External walls require a thermal insulation rating, and in general all concrete walls will require additional insulation. Technical manuals for the wall system should provide recommendations for added insulation necessitated by the climate zone.
Designed for purpose
AFS Rediwall is a CodeMark Certified, PVC permanent formwork system for use in load bearing and non-load bearing reinforced concrete walls. The Rediwall Codemark Certificate confirms compliance to the BCA pillars listed above.
Rediwall applications are designed in accordance with AS3600, as all reinforced concrete structures are required to.
A detailed Fire Engineering assessment of the Rediwall system has been conducted in addition to comprehensive fire testing, which documents varied conditions and applications to provide fire engineered solutions to provide further supporting to project Fire Engineers & Certifiers.
Rediwall has been successfully tested and assessed to achieves an FRL up to 240/240/240, has a Group Number 1 classification for internal walls and passed AS5113 for no flame spread for external walls
Rediwall presents a weatherproof external wall system and lends itself to any cladding system.
Rediwall systems have numerous construction options to achieve acoustic performance requirements.
Rediwall construction options ensure wall systems achieve target thermal R values for all climate zones.
Rediwall system options are available on the AFS Specification Finder which can be found on the AFS homepage.
To ensure your next project is certified, specify AFS Rediwall CodeMark Certified PVC formwork for your load bearing and non-load bearing, external and internal walls. For further information on AFS Rediwall contact the AFS Technical Team on 1300 727 237.