Folded sheet aluminium is aluminium sheet bent to specified dimensions and angles. This creates a profile that covers an edge, corner or junction on a building. It is widely used around façade systems, window frames, doors and roof edges because it can be precisely tailored to a construction detail.
The term refers to the forming process. A flat sheet is bent along one or more lines using a sheet metal folding machine. The result may be a simple angle profile or a profile with several flanges and return edges. The correct shape depends on where the component will be installed and the function it serves there.
How does folded sheet aluminium differ from standard aluminium profiles?
Standard profiles have a fixed cross-section and are generally supplied in stock lengths. Folded sheet aluminium is formed from sheet material for a specific junction. This allows widths, angles and folded edges to be tailored to the project dimensions.
This makes folded sheet aluminium suitable for details where no standard profile fits. However, it is not simply an arbitrary strip of metal used to hide a gap. The shape, sheet thickness, fixings and substrate must suit the application. The detail must also work with the façade construction and any ventilation or drainage provisions included in the design.
What shapes are commonly used for folded sheet aluminium?
The cross-section of a component determines how it can be installed and which surfaces remain visible. Common shapes include L-sections for corners, U-sections for enclosures and Z-sections for connecting two offset surfaces. Cover caps and profiles with multiple folds are also made for project-specific details.
A folded edge can stiffen the sheet and often gives the exposed end a neater appearance. The options are limited by factors including sheet thickness, bend radius and the space needed to install the component. The cross-section should therefore be finalised before production, preferably with a clear sketch showing all dimensions and angles.
Sheet thickness, alloy and surface finish
Not all aluminium sheet behaves in the same way during folding and installation. The chosen alloy and sheet thickness must suit both the fabrication process and the application. A longer or wider component may have different requirements for stiffness and fixing than a small corner piece. These choices form part of the technical specification for the detail.
Exposed surfaces may be painted or have another finish. The colour and gloss level are matched to adjacent façade components. Bear in mind that colour perception also depends on the lighting, the orientation of the sheet surface and differences between material batches. Protective film prevents damage in transit, but must be removed carefully and within the timeframe specified in the product information.
Where is folded sheet aluminium used?
Around façade systems and curtain walls
On aluminium façades, folded sheet metal is used for end faces, external and internal corners, junctions with building components and transitions between different façade planes. The detail then follows the dimensions and lines of the façade system. On a curtain wall folded sheet metal may be used along edges where the system meets a roof, floor, wall or another part of the façade.
Around window frames and doors
Around window frames and doors, folded sheet metal can cover a reveal, head or side junction. The profile bridges the transition between the element and the adjacent façade. Sightlines matter here: uneven joints or inconsistent angles stand out immediately beside straight window frame and door profiles.
At roof edges, fascia boards and parapets
Aluminium sheet metal is also used to finish roof edges, fascia boards and the tops or sides of parapets. The build-up must suit the underlying construction detail. Folded sheet metal does not automatically replace a waterproofing layer or other provision; the design and installation must work together as a whole.
In renovation work and repairs to junctions
In renovation work, bespoke components can cover an existing, irregular transition or connect a new façade build-up to retained building components. Accurate site measurement is particularly important, as walls and edges are not always straight, flat or square. Several components or adjusted joints may be needed to accommodate dimensional variations in a controlled way.
Why dimensions must be finalised before production
Folded sheet metal is made to specified dimensions. Any error in width, angle or the sequence of folds will therefore be reflected in the finished product. Recording only the overall dimensions is often insufficient. It must also be clear which side is visible, how the profile overlaps other components and where space is needed for fixings.
Site measurements must take account of the actual substrate and the intended joint layout. Measure at several points where the existing dimensions may vary. Also check whether adjacent components are already in their final positions. If measurements are taken before another building component moves, the fabricated sheet metal may no longer fit as intended.
Installation considerations
Folded aluminium sheet metal must be installed flat and with minimal stress. An uneven substrate can show through on the exposed surface. Fixings that are overtightened or incorrectly positioned can also distort the sheet. The fixing method depends on the detail, the substrate, the component length and the project's technical information.
Aluminium expands and contracts with changes in temperature. The detail must allow for this movement, particularly with longer components. Joint layout and fixing positions therefore need attention before installation. Sealant beads or seals should only be used where specified in the design and must be compatible with adjacent materials.
The page on aluminium finishing by ACS Montage describes the installation service. State in your enquiry who is responsible for site measurement, production and delivery; these are not automatically included in an installation order. For the usual steps from enquiry to inspection, you can also view the methodology for more information.
Practical checklist for folded aluminium sheet metal
Before ordering and installation, check at least the following:
- the final dimensions of all exposed surfaces, flanges and return edges;
- the angles and the sequence in which the sheet is folded;
- the exposed side and the direction of the surface finish;
- the specified sheet thickness, alloy, colour and gloss level;
- the condition, flatness and composition of the substrate;
- the overlap or junction with adjacent components;
- the chosen fixings and access to them;
- the joint layout and allowance for thermal movement;
- the installation sequence in relation to window frames, façade panels and seals;
- protection during transport, storage and installation.
To see how these details are used in completed work, view the projects featuring façades and aluminium finishing.
Frequently asked questions about folded aluminium sheet metal
Is folded aluminium sheet metal the same as aluminium sheet metal?
Sheet metal is the broader term for components made from sheet material. Folded sheet metal is bent along one or more lines. A flat cover plate is therefore sheet metal, but is not necessarily folded sheet metal.
Can folded sheet metal be made to measure on site?
The final folds are normally formed using suitable machinery, based on the recorded dimensions. Minor adjustments may be needed on site, but major dimensional corrections can adversely affect the shape, finish or fit.
Can folded aluminium sheet metal accommodate every construction irregularity?
No. It can finish a transition and accommodate minor dimensional variations within a carefully designed detail. An unsuitable substrate, missing waterproofing or structural problem must be assessed and resolved separately.
What information is needed for installation?
A dimensioned sketch, photographs, information about the substrate and a description of the intended junction are a good starting point. Also state whether the folded sheet metal has already been fabricated and which fixing or sealing details have been specified.
Have an aluminium detail assessed
Do you have a façade edge, window frame junction or another aluminium detail that needs installing? Use the contact page to share the location, photographs and any available dimensioned sketch. Also state whether the folded sheet metal has already been fabricated and who is arranging delivery.