Insight / ACP vs Curtain Wall
The question is not ACP or curtain wall. The surface decides.
Curtain wall goes where a surface has to be seen through and has to carry wind and rain as one system. ACP covers the solid areas, hanging on framing behind it that carries the load in its place. Many buildings use both on different surfaces, so the decision that actually costs money is where the line between them falls.
When to use ACP, and when to use curtain wall
On most buildings the question about daylight closes the argument about cost per square metre before that argument starts.
Does the surface need to be seen through
If the space behind it needs daylight and a view, that surface is glass, and glass across a wide surface means curtain wall. ACP closes it. Settle this one first: no saving per square metre is worth an office floor that has lost its light.
What carries the wind load
Curtain wall carries wind pressure and rain as one system, spanning between floor slabs. An ACP panel spans nothing. It hangs on aluminium framing behind it, and that framing carries the load. So every ACP quotation needs to say what the framing behind it is: the same panel reads flat or rippled depending on how far apart that framing sits.
Where the waterline sits
In curtain wall, the line between outside and inside runs inside the system itself, through joints that can be tested as one assembly. In ACP it sits behind the panel: water does get through the joints, and is then drained back out at a chosen point. Both are legitimate, and each needs a different set of detail drawings.
The solid band between floors
The strip across the floor beam is the surface most often argued over. It can be spandrel glass inside the same curtain wall run, or ACP on its own framing. The second option adds one system junction on every floor.
Fins, ornament and angled elements
Elements like these sit outside both systems. ACP folded into a shape needs concealed joints, which then have to be sealed, plus a backing frame to hold the shape up. For some shapes, an extruded aluminium profile can make the same element in a single length with fewer joints.
How tall the building is
Height makes both decisions more demanding. ACP core type has to be specified with the building's height and use. Curtain wall can be stick or unitized; geometry, panel repetition, installation access, and project performance criteria determine the choice.
What an ACP price covers, and what a curtain wall price covers
A per-square-metre figure for ACP and one for curtain wall measure different scopes, so setting them side by side is not yet a comparison.
A curtain wall price needs to cover its system: framing, a wind load calculation, drainage, and joints. An ACP quotation can include panel and framing at different scopes. Comparison starts to mean something once both quotations show the same work on the same surface.
If what you need is an installed price for ACP against a scope somebody else has already fixed, that work has its own market and we are not the right firm for it. If the framing, the junction detail and the liability for a leak are things you are buying, then the two figures in front of you are measuring two different things.
What the acronym stands for, what is inside the panel, how the core types differ and why a surface ends up rippled are not covered here.
Who owns the junction line
On a real building ACP and curtain wall are used together. Everywhere the two meet there is a junction line that has to be drawn, and that line frequently falls outside the scope of both parties building it.
The glass is built by one party working to its own system drawings. The ACP is built by another, sometimes from a different supplier, working to its own framing drawings. Between them sits a few centimetres that has to hold water out, absorb thermal movement, and still look clean from street level.
That junction line can be missed in a quotation. When it is first argued over after panels are ordered, resolving it becomes extra work that was not budgeted. A leak that shows up after the building is occupied can start on this line.
When we hold both systems in one scope, the junction can be drawn and carried in the same set of drawings. Where scopes are split, the owner of the detail needs to be named in the specification.
So the order that saves money starts from the job each surface has to do: pass light, carry wind, or make a shape. Material follows from that, and the junction line between two materials gets drawn at the same time.
Questions we get asked
Most arrive while the facade specification is still being written.
- Which is cheaper, ACP or curtain wall?
- The system name is not enough to answer that question. A surface that needs to be seen through needs glass; a solid surface can use ACP or spandrel. Price can only be compared once framing, junction detailing, installation access, and responsibility at the joint appear in both quotations.
- Can ACP be used across a whole facade?
- Technically yes, on surfaces that genuinely do not need to be seen through. What changes is the space behind it. An office floor with no glass loses daylight and its view, and the cost of lighting it artificially runs every day the building is occupied. In practice ACP closes the solid areas while the surfaces occupants look through stay glass.
- What is the difference between ACP and curtain wall?
- Curtain wall is the outside wall itself: it replaces the building's wall, spans between floor slabs, and carries wind and water as one system. ACP is a surface fixed to framing behind it, and that framing is what carries the load. As a decision, the difference is whether you are buying a system or buying a surface, and many buildings use both on different parts of the elevation.
- What changes when ACP goes on a high-rise?
- At that height the core type stops being a budget question. Two panels with different cores look identical once installed, then behave very differently in a fire, and what decides that is not the brand but what sits in the middle. The core type therefore gets specified alongside the building's height and its use. Which requirements apply is set by local building regulations and the project's fire consultant, not by the panel supplier.
- Who carries the junction between ACP and curtain wall?
- The party whose drawings cover that line. On a two-supplier project, the line needs an explicit owner. When we hold both systems in one scope, the junction can be drawn and carried in the same set of drawings. Where scopes are genuinely split, name the owner in the specification before panels are ordered.
- For fins and ornament, ACP or extruded aluminium?
- For some shapes, an extruded profile can be the more suitable alternative. ACP folded into a fin needs concealed joints and backing framing. A single extrusion can make the same profile with fewer joints, but size, support, finish, and package cost still need to be compared on the same drawing.