How an Aluminium Curtain Wall Is Installed
A curtain wall is the building’s outer skin — a non-structural aluminium-and-glass envelope hung off the floor slabs, carrying its own weight and the wind, but no building load. On an Airport City tower or a corporate headquarters it is the most visible thing about the building and the most demanding to get watertight. This guide explains how a curtain wall actually goes up, so a developer or project manager can tell a properly installed façade from one that will leak.
Aluminium Installers Ghana engineers and installs curtain wall across Ghana — see our Curtain-Wall Installation and Façade Engineering services — and the discipline below is what separates a sealed envelope from a wet one.
Stick vs Unitised — Two Ways to Build a Façade
Stick System
The curtain wall is assembled piece by piece on site: vertical mullions are fixed first, horizontal transoms locked between them, and glass or infill panels glazed into the grid afterward. More site labour, more on-site sealing, and slower — but flexible, lower in tooling cost, and well suited to lower-rise and irregular elevations. The stick approach is the common choice on much Ghanaian commercial work.
Unitised System
The façade is built as factory-made storey-high panels — frame, glass and seals already assembled — then craned into place and locked together on site. Faster on site, more consistent in quality because the sealing is done in a controlled workshop, and the usual choice for tall towers where site access and speed dominate. Higher tooling and transport cost.
| Stick | Unitised | |
|---|---|---|
| Assembled | On site, piece by piece | In factory, storey-high panels |
| Site speed | Slower | Faster |
| Sealing quality | Site-dependent | Workshop-controlled |
| Best for | Low/mid-rise, irregular | Tall towers, repetitive grids |
How It Anchors to the Structure
A curtain wall hangs off the building, so the anchoring decides everything. Brackets are fixed to the floor slabs or edge beams and the mullions hung from them. The anchors must do three things at once:
- Carry the dead weight of the glass and aluminium
- Transfer wind load — positive and negative — back into the structure
- Allow movement — thermal expansion of the aluminium and structural deflection of the building — without stressing the glass
Get the movement allowance wrong and the glass cracks or the seals fail. This is why the anchoring is engineered, not improvised.
Keeping the Water Out — The Rain-Screen Principle
A good curtain wall does not rely on a single line of sealant. It works on pressure equalisation: an outer rain-screen sheds most water, a drained and ventilated cavity behind it lets any water that gets in run back out through weep holes, and the inner line provides the air seal. Water is managed, not just blocked — because on a tall façade, sealant alone will eventually be breached, and a drained system survives that.
Sealing
- Gaskets — factory-set EPDM seals in the framing carry the primary weather line.
- Wet seals — structural and weather silicone applied where the design calls for it, in controlled conditions, to a real joint design.
- Movement joints — sized to absorb thermal and structural movement so the seal is never asked to stretch beyond its capacity.
On-Site QA — Proving It Before Handover
A façade is only as good as the test that proves it. Curtain wall performance is verified to real standards:
- ASTM E283 — air leakage (infiltration)
- ASTM E331 — water penetration under static air-pressure difference
- ASTM E330 — structural performance under positive and negative wind load
- AAMA 501 — methods for field (on-site) testing of installed curtain wall, including field water-spray testing of the installed façade
- EN 1090 — execution of the aluminium structure (EN 1090-3 for aluminium)
On-site water testing of the installed wall, before the scaffold comes down, is what turns “it looks finished” into “it is proven watertight.” We test, document and hand over.
Frequently Asked Questions
What’s the real difference between stick and unitised? Where the panels are assembled. Stick is built piece by piece on site; unitised arrives as factory-made storey-high panels and is craned in. Unitised is faster and more consistent on tall towers; stick is flexible and common on low- and mid-rise Ghanaian work.
How does a curtain wall handle building movement? The anchoring is designed to allow thermal expansion of the aluminium and structural deflection of the building, so the glass and seals are never over-stressed. Movement joints absorb the rest. Ignoring movement is a classic cause of cracked glass and failed seals.
Can a curtain wall be tested on site, not just in a lab? Yes — AAMA 501 covers field testing of the installed façade, including water-spray testing. On-site testing before handover is the honest proof that the envelope is watertight as built, not just as designed.
Is the 10-year warranty a standard? No. Our decade-long warranty is our own commercial guarantee on the installation. The standards above (ASTM, AAMA, EN 1090) are the industry test and execution standards; the warranty is a commercial commitment on top of them.
Build a Façade That’s Proven, Not Just Finished
We engineer the system to the elevation, anchor it to carry weight, wind and movement, seal it on the rain-screen principle, and test the installed wall before the scaffold comes down. See Curtain-Wall Installation, Façade Engineering and Structural Glazing, or call +233 27 011 3728 to discuss a façade across Greater Accra, Kumasi and Takoradi.