A ventilated facade is a cladding assembly where the outer screen is separated from the inner wall by a continuous air cavity, open at the top and bottom to allow air movement. It is the dominant approach for multi-storey aluminium cladding in Australia, and for good reason - it manages moisture, improves thermal performance, and extends the life of the building envelope by protecting the structure behind it.
If you are specifying or reviewing a facade system for a Class 2 to Class 9 building, understanding how a ventilated facade actually works - not just as a product, but as a set of physical principles - is essential to getting the detail right and avoiding problems that only emerge years after handover.
How Does a Ventilated Facade Work?
The principle is straightforward. The outer cladding is the first line of weather defence, but it is not expected to be perfectly sealed. Behind the cladding sits a ventilated air cavity - typically 20mm to 50mm deep - backed by a secondary waterproofing membrane on the building structure.
This is fundamentally different from a barrier wall system, where the outer cladding itself is the waterproofing layer. In a barrier system, the entire pressure differential from wind-driven rain acts across a single skin, and any breach in that skin allows water directly into the wall assembly. A ventilated facade works on a different premise: accept that some moisture will reach the cavity, and manage it there.
Three mechanisms do the work:
- Deflection. The outer cladding stops the vast majority of rainwater before it reaches the cavity. On a well-designed system, upwards of 95% of wind-driven rain never gets past the outer screen.
- Drainage. The small volume of water that does penetrate runs down the back of the cladding or the face of the membrane and drains out at the base of the wall through weep openings.
- Ventilation. Air movement through the cavity - driven by thermal buoyancy and wind - dries any residual moisture. Warm air rises within the cavity and draws cooler air in from the base, maintaining a continuous drying cycle.
In properly designed systems, a fourth mechanism also contributes: pressure equalisation. When wind acts on the outer cladding, air moves through joints and openings into the cavity, raising the cavity pressure toward the external pressure. This reduces the net pressure differential driving rain through joints and fixings. It is a subtle but significant effect, particularly on taller buildings and in higher wind zones.
What Are the Components of a Ventilated Facade Assembly?
A complete ventilated facade has six distinct layers, each performing a specific function. Getting any one of them wrong compromises the system, so it is worth understanding each clearly.
Outer cladding - the weather screen. This is the visible face of the building and the primary rain deflector. In aluminium facade systems, this is typically an interlocking rainscreen panel such as interloQ or a solid aluminium panel such as element13. The cladding takes the environmental load - UV, rain, temperature cycling, impact - so the rest of the assembly does not have to.
Ventilated cavity - drainage and drying. The air gap between the cladding and the insulation or membrane layer. Depth is typically 20mm to 50mm, depending on the system and the building’s exposure conditions. The cavity must be continuous and unobstructed to allow drainage and airflow. Blocked cavities - from mortar droppings, insulation bulge, or debris - defeat the purpose of the system.
Subframe and brackets - structural support. The cladding is fixed to the building structure via a subframe, which may be aluminium battens (such as conneQt), steel angles, or proprietary bracket systems. The subframe creates the cavity depth, transfers wind loads from the cladding to the structure, and accommodates building movement and construction tolerances.
Insulation - thermal performance. In a ventilated facade, the insulation sits continuous on the inner wall, behind the cavity. This is a critical point. Because the insulation is not interrupted by the cladding layer, it avoids the thermal bridging that occurs in systems where the cladding is fixed directly through the insulation. The result is a more thermally efficient envelope. For Type A and Type B buildings under NCC 2022, the insulation must be non-combustible.
Sarking or membrane - secondary waterproofing. This is the final line of defence against moisture reaching the inner wall. It sits on the face of the insulation or the inner wall, behind the cavity. NCC Volume 1 C2D10(6)(f) provides a concession for sarking less than 1mm thick with a flammability index of 5 or less, allowing its use within non-combustible facade assemblies without triggering additional compliance requirements.
Inner wall - structural backing. The structural wall behind the entire assembly. This may be concrete, masonry, or steel frame with lining. In a properly functioning ventilated facade, the inner wall is shielded from direct weather exposure, UV, and the majority of temperature cycling.
What Are the Performance Benefits?
The ventilated facade approach delivers measurable advantages across several performance criteria. These are not theoretical - they are observable on real buildings over real service lives.
Moisture Management
This is the primary advantage. Trapped moisture within a wall assembly is the single biggest cause of long-term envelope failure in sealed systems. It drives corrosion of steel framing, degradation of insulation, mould growth, and progressive deterioration of internal finishes. A ventilated cavity eliminates the conditions for trapped moisture by providing continuous drainage and evaporation. The assembly can tolerate minor imperfections in installation - a slightly misaligned joint, a small penetration - without catastrophic failure, because the cavity manages what gets through.
Thermal Performance
Continuous insulation behind the cladding is inherently more effective than insulation interrupted by fixings and cladding elements. The ventilated cavity also contributes to thermal performance, particularly in summer. Solar radiation heats the outer cladding, which in turn heats the air in the cavity. That heated air rises and exits at the top, carrying heat away from the building before it reaches the insulation layer. This passive ventilation effect can meaningfully reduce cooling loads on sun-exposed elevations.
Durability
The inner wall and structural elements are protected from direct UV exposure, rain impact, and the temperature cycling that causes expansion and contraction fatigue. The cladding takes the environmental load, and because it is mechanically fixed rather than adhesively bonded, individual panels can be replaced without disturbing the rest of the assembly. The practical result is a facade that degrades predictably and can be maintained without wholesale replacement.
Acoustic Decoupling
The air cavity separates the outer cladding from the inner wall, reducing direct sound transmission. This is not a substitute for dedicated acoustic treatment in noise-sensitive applications, but the decoupled mass-air-mass arrangement provides measurable improvement compared to a single-skin or direct-fix system.
Pressure Equalisation
In taller buildings and higher wind zones, pressure equalisation within the cavity reduces the net force driving rain through cladding joints. This is a significant advantage for systems with open or drained joints - the physics of the cavity work in favour of keeping water out, rather than relying entirely on sealant integrity.
How Do Valmond & Gibson’s Systems Fit?
Valmond & Gibson supplies aluminium facade systems designed around ventilated facade principles.
interloQ is an interlocking rainscreen panel extruded from 6060/6063 aluminium alloy. The interlocking profile creates inherent weather resistance even with open horizontal joints - water that reaches the joint face is deflected by the profile geometry before it enters the cavity. The system has been tested as a complete assembly to AS/NZS 4284 at plus and minus 1500Pa serviceability limit state, demonstrating weather performance under simulated wind-driven rain conditions. interloQ is available in powder coat, anodised, and woodgrain finishes, and can be installed vertically or horizontally.
element13 is a 3mm solid aluminium panel, typically installed with open joints on a ventilated subframe. In an open-joint configuration, element13 relies directly on the cavity drainage principle - water that enters through joints drains harmlessly down the back of the panel and exits at the base. element13 panels are PVDF-coated for long-term UV and corrosion resistance, and have been independently tested to AS/NZS 4284 at plus and minus 1500Pa SLS.
conneQt is an aluminium batten and adaptor system that forms the subframe layer. conneQt creates the ventilated cavity, transfers wind loads from the cladding to the structure, and provides the fixing substrate for interloQ or element13 panels. It is extruded from the same 6060/6063 alloy as interloQ, ensuring material compatibility across the assembly.
Both interloQ and element13 are non-combustible, tested by CSIRO to AS 1530.1. This is a prerequisite for ventilated facade use on Type A and Type B construction under the NCC.
What Should You Consider During Design?
Several design decisions determine whether the ventilated facade performs as intended over its service life.
Cavity depth. Deeper cavities provide better ventilation and drainage but increase the facade build-out from the structural wall. For most aluminium cladding applications, 25mm to 40mm is typical. Coastal and high-exposure locations may warrant deeper cavities. The key is maintaining continuous, unobstructed airflow from the base vent to the top vent.
Vent openings. The cavity must be open at the top and bottom of each storey, or at the top and bottom of the facade if continuous. Vent openings need to be sized for adequate airflow while preventing pest and debris ingress. Perforated flashings or mesh-backed openings are standard practice.
Insulation type. For multi-storey buildings classified as Type A or Type B, all insulation within the facade assembly must be non-combustible. This effectively limits choices to mineral wool or similar non-combustible products. Combustible insulation within a ventilated cavity creates an unacceptable fire risk regardless of building classification.
Membrane selection. The sarking membrane must be vapour-permeable enough to allow the wall assembly to dry inward (particularly relevant in air-conditioned buildings in humid climates) while maintaining water holdout performance. The NCC concession for sarking under 1mm with a flammability index of 5 or less keeps the non-combustible compliance pathway straightforward.
Fire stopping. While the NCC does not impose a specific DTS requirement for cavity barriers within non-combustible ventilated facade assemblies - because the cladding, insulation, and framing are already non-combustible - designers should consider cavity closers at fire compartment boundaries and around openings to limit smoke and hot gas movement within the cavity during a fire event.
The Bigger Picture
The ventilated facade is not new technology. It has been the standard approach for medium and high-rise cladding in Europe for decades, and it has become the dominant method for aluminium facade systems in Australian construction. The reason is simple: it works with the physics of moisture and heat rather than against them. Instead of demanding perfection from a single barrier, it builds in redundancy and manages what gets through.
For architects and specifiers, the ventilated facade is not just a product choice - it is a performance strategy for the building envelope. Getting the principles right at the specification stage means fewer problems at handover, fewer maintenance calls in the first decade, and a facade that performs predictably across its full service life.
Related Reading
- Rainscreen vs Direct-Fix Cladding: Which Approach Suits Your Project?
- Thermal Bridging in Aluminium Facade Systems
- interloQ Specification Guide: Everything You Need to Know
- Subframe Design for Aluminium Rainscreen Cladding
Last updated: 4 April 2026