Steel vs Aluminium Windows: How to Choose
Steel and aluminium are the two materials people weigh up when they want a slim, modern window. Both can look minimal, but they behave differently. This comparison covers the points that actually affect the decision.
Sightlines and aesthetics
Steel is stronger, so it achieves the slimmest sightlines and the authentic crittall-style grid. Aluminium frames have improved but generally need a wider section to carry the same glass.
If you want a genuine heritage look — especially in a period or conservation property — steel is hard to beat.
Strength and longevity
Steel windows are renowned for longevity; properly galvanised and finished, they last for decades and resist warping. Aluminium is light and corrosion-resistant but softer, which is why it needs more frame to stay rigid.
For large doors and tall screens, steel's rigidity is a real advantage.
Thermal performance and cost
Both materials conduct heat, so both rely on a thermal break for good efficiency. Thermally broken steel (such as a W50 section) and modern aluminium both perform well with insulated glazing.
Aluminium is typically the cheaper option up front. Steel costs more, but buyers choose it for the unmatched sightlines, character and lifespan — it is a long-term investment rather than the budget choice.
Frequently asked
- Is steel more expensive than aluminium?
- Usually yes. Steel commands a premium for its slimmer sightlines, strength and longevity, while aluminium is the more budget-friendly option.
- Which lasts longer?
- Both last well when made properly, but steel is exceptionally durable and rigid, which is why heritage steel windows often survive a century.
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