Aluminium expands and contracts with temperature. The coefficient of linear thermal expansion for standard facade alloys (6060-T5, 6063-T6) is 23 µm/m/°K - that is, 0.023 mm per metre per degree Celsius. This is a known, predictable property, and designing for it is straightforward once you understand the numbers.
How does aluminium compare to other facade materials?
Aluminium moves roughly twice as much as steel (12 µm/m/°K) and about three times as much as concrete (8-12 µm/m/°K). This is not a disadvantage - it simply means the fixing and joint design needs to account for it. Every aluminium facade system on the market accommodates thermal movement. The problems only start when fixings or joints are detailed incorrectly.
How much does a panel actually move?
Here is a worked example using real Australian conditions.
Take a 6-metre interloQ panel on a building in Sydney. Surface temperatures on a facade range from about 5°C on a winter night to 65°C on a dark-coloured panel in direct summer sun. That gives a temperature range of 60°C.
The calculation:
Movement = Length (mm) x Coefficient x Temperature Range
Movement = 6,000 x 0.000023 x 60 = 8.3 mm
That 6-metre panel moves about 8 mm between its coldest and hottest states. Not enormous, but enough to buckle a panel or pop a fixing if the detail does not allow for it.
For an element13 panel at 4,000 x 1,500 mm under the same conditions, the movement works out to 5.5 mm along the length and 2.1 mm across the width. Joint design must accommodate movement in both directions.
Does colour matter?
Yes. Dark colours absorb more solar radiation and reach higher surface temperatures. A very dark panel (charcoal, black, deep bronze) can hit 75-80°C in the Australian sun, while a light colour might only reach 40-50°C. That difference changes the temperature range from 60°C to potentially 75°C - and the movement calculation scales accordingly.
For the same 6-metre panel in a very dark colour:
Movement = 6,000 x 0.000023 x 75 = 10.4 mm
If your project uses dark colours on long panels, the movement allowance needs to reflect it. This is especially relevant for west-facing elevations, which take sustained afternoon sun.
How do Valmond & Gibson systems accommodate thermal movement?
Each system handles it differently, matched to how it is installed.
interloQ (interlocking rainscreen): The panels ship with pre-punched slotted fixing holes. One end of the panel is fixed firmly to establish a datum point. The remaining fixings use the slots, allowing the panel to slide freely as it expands and contracts. The critical installation rule: do not over-tighten slotted fixings. A snugged-up slot defeats the entire purpose of the detail and turns a sliding connection into a fixed one.
165CW (unitised curtain wall): Designed from the ground up for movement. The stack joint accommodates +/-25 mm of vertical movement, and mullion connections allow +/-10 mm of horizontal movement. The three-part bracket system provides controlled movement between the unitised panels and the building structure.
element13 (solid aluminium panels): These panels expand in both length and width, so the perimeter joint design must allow movement in two directions. Fixing details use a combination of fixed and slotted connections to manage bi-directional expansion. Joint widths between adjacent panels are sized during design to prevent contact at maximum expansion.
What about differential movement with the structure?
The building frame - whether concrete or steel - expands at a different rate to the aluminium cladding fixed to it. The subframe and bracket system must accommodate this differential movement. A concrete floor slab and the aluminium panel bolted to it will not expand by the same amount on a hot day. The bracket design absorbs the difference, which is why facade brackets use slotted or oversized holes as standard.
This is also why facade engineers specify movement joints at defined intervals in the subframe, not just in the cladding panels themselves. The subframe is part of the movement chain.
What is the most common mistake?
Fixing panels rigidly at both ends. When a panel is locked at each end, it has nowhere to go as it heats up. The result is bowing, oil-canning, or distortion - visible from the ground and difficult to fix without removing panels.
The principle is simple: fix one point, slot everything else. This applies to panels, to subframe members, and to any continuous aluminium element on the facade.
Where to find fixing details
Valmond & Gibson technical documentation for interloQ, element13, and 165CW includes fixing arrangement drawings that show correct slotted fixing layouts for thermal movement. These are available on request and are included in project-specific submittals. If you are detailing a facade and need the fixing arrangements, get in touch - the documentation exists to make the installation straightforward.
Related Reading
- Thermal Bridging in Aluminium Facade Systems
- Subframe Design for Aluminium Rainscreen Cladding
- Measuring for Aluminium Cladding: Tolerances and Best Practice
- Dissimilar Metal Corrosion in Facade Assemblies
Last updated: 4 April 2026