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Specification · Updated 2026

Where aluminium works best on modern projects

Aluminium is strongest where slim sightlines, larger openings, colour choice, stiffness and clean detailing matter more than a lowest-cost frame.

Large glazed openings where slim sightlines matter

Aluminium earns its place where the spec leads with a big opening and minimal frame. The strength-to-weight ratio lets a fabricator run slim profiles and tall sashes that PVCu and timber cannot match at the same dimensions, so more of the opening reads as glass.

Bifolds, sliders and lift-and-slide doors are the obvious calls. A single sliding pane carries serious glass weight on a narrow frame, and stacked or pocketed leaves clear the reveal. For full-height runs across a rear elevation, aluminium pulls ahead on sightline and span.

Specify aluminium bifold doors and aluminium sliding doors when the brief leads with glazed area and the install needs to hold flat over a wide opening.

Slim windows that hold thermal performance

Polyamide thermal breaks separate the inner and outer skins of the profile, so a slim aluminium frame still meets the performance the project is signed off against. The sightline stays tight without giving up on the glazing spec.

Casement and tilt-and-turn formats suit most modern elevations: flush lines, large panes, secure background ventilation and inward cleaning on upper floors. Match the glazing unit and frame to the U-value the design team is working to rather than chasing a headline number.

See aluminium casement windows and aluminium tilt and turn windows, and the energy efficiency page for how frame and glass combine.

Rooflights and structural roof glazing

Flat roofs and single-storey extensions are a strong fit. Roof lanterns and flat rooflights carry glass over a wide aperture on slim rafters, so daylight comes in without a heavy grid breaking up the view.

The frame holds its line under load and movement, and the finish takes weather without the maintenance a timber lantern needs. On a contemporary extension this is usually the cleanest way to bring top light into the plan.

Commercial entrances, framing and curtain walling

On commercial work aluminium is the default for high-traffic entrances and large facades. Entrance doors take repeated daily use on heavy-duty hinges and closers, and shopfront framing holds large glazed panels in a slim grid.

Curtain walling spans floor to floor as the building envelope, carrying weather resistance and heat retention across the elevation. Specify curtain walling under BS EN 13830 and doors and screens under BS EN 14351-1, with UKCA marking and a Declaration of Performance supporting the products supplied.

For commercial packages see commercial doors and framing and aluminium entrance doors.

Spec it with the right route

Steel-look and heritage details work the same way. Aluminium delivers the slim black profile of steel-look internal doors without the weight or corrosion risk of fabricated steel, and heritage door styles hold period proportions in a frame that meets current performance.

VitrineAlu fabricates to trade in North West England and is a Council for Aluminium in Building member. For pricing and lead times, send the opening sizes and glazing spec to us at the quote page.

Homeowners are not sold direct. Use find an installer to reach a vetted installer who fits VitrineAlu products.

Common questions

When should I specify aluminium over PVCu or timber?

Choose aluminium when the opening is large, the sightline needs to stay slim, or the frame carries heavy glass over a wide span. It suits bifolds, sliders, rooflights and commercial facades. For small standard windows on a tight budget, PVCu may be enough. Aluminium wins on span, slimness and finish life.

Does a slim aluminium frame lose thermal performance?

Not when it is thermally broken. A polyamide break separates the inner and outer skins, so the frame meets the performance the project is signed off against while keeping a tight sightline. Match the frame to the glazing unit and the target U-value rather than judging the frame width alone.

Is aluminium suitable for commercial curtain walling and entrances?

Yes. Aluminium is the standard choice for curtain walling, shopfronts and high-traffic entrances because it spans large facades on slim grids and takes repeated daily use. Curtain walling is specified under BS EN 13830 and doorsets under BS EN 14351-1, with UKCA marking and a Declaration of Performance supporting the supply.

Where does aluminium make the biggest difference on a modern extension?

On the glazed elements. Bifold or sliding doors across the rear, slim casement or tilt-and-turn windows, and roof lanterns or flat rooflights overhead all rely on the strength-to-weight ratio to keep frames slim and spans wide. That combination delivers the open, daylight-led plan most modern extensions are designed around.

Related VitrineAlu product types

Trade product type

Aluminium Bifold Doors

Slimline aluminium bifold doors that fold a whole wall of glass aside for garden openings, extensions and renovations.

Trade product type

Aluminium Casement Windows

Slimline and high-performance aluminium casement windows with clean sightlines and strong thermal and acoustic options.

Trade product type

Aluminium Tilt & Turn Windows

Tilt-and-turn and hidden-vent aluminium windows combining secure ventilation, easy cleaning and a clean facade line.

More VitrineAlu trade guidance

Bring light into living.

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Send sizes, drawings or a quick project brief. VitrineAlu will confirm the right product specification for the project at quote.