Most window comparisons are two-way. In practice a project chooses between four materials, and each fails in a different way — which is more useful to know than which one "wins".
This is a four-way comparison on the criteria that actually determine how a window performs over a building's life.
The four materials
Timber — the historical default. Good thermal performance, genuine visual quality, and a maintenance cycle that never ends.
Mild steel — still common in older Indian construction and in industrial applications. Strong and cheap; conducts heat readily and corrodes without sustained upkeep.
Aluminium — the modern lightweight option. Stiff, slim, fully recyclable, and a thermal bridge unless it has been thermally broken.
uPVC — rigid, non-conductive, dimensionally stable, and needing steel reinforcement for larger spans.
Compared on what matters
| Criterion | Timber | Mild steel | Aluminium | uPVC |
|---|---|---|---|---|
| Thermal conductivity | Low | Very high | Very high unless broken | Low |
| Moisture stability | Swells and shrinks | Stable but rusts | Stable | Stable |
| Corrosion | Rots | Rusts readily | Pits in coastal air | None |
| Pest risk | Termites | None | None | None |
| Maintenance | Repaint every 3–4 years | Anti-rust treatment | Washing; coating repair | Washing |
| Corner joints | Mechanical, move over time | Welded | Mechanical, can loosen | Fusion welded |
| Span capability | Good | Excellent | Excellent | Good with reinforcement |
| Sightlines | Slim | Very slim | Slim | Wider sections |
| Repairability | Fill and refinish | Weld and repaint | Limited | Section replaced |
How each one fails
More instructive than how each performs when new.
Timber fails by movement. Seasonal swelling and shrinking works on the seals and the joints. It is gradual, it is predictable, and it is arrested by maintenance rather than cured.
Steel fails by corrosion. Rust starts at any breach in the protective coating and spreads under it. Once established, it is difficult to stop without stripping back.
Aluminium fails at the joints and the coating. Mechanical corners loosen slightly under thermal cycling; coatings pit in salt air where they have been breached.
uPVC fails at the hardware, not the frame. Hinges, locks, rollers and gaskets wear. All are serviceable without replacing the window, which is the practical distinction — the failure mode is maintainable rather than terminal.
Cost across a building's life
Purchase price ranks them roughly: mild steel cheapest, then untreated aluminium, then uPVC and timber comparable, then thermally broken aluminium.
Whole-life cost reorders them substantially. Timber accumulates repainting every few years plus pest treatment. Steel accumulates anti-rust work. Aluminium accumulates coating repair, more so near the coast. uPVC accumulates occasional gasket and hardware servicing.
Over twenty-five years the ordering by total cost looks very different from the ordering by quotation — which is the argument for asking about maintenance before comparing prices.
Choosing by situation
Heritage or conservation project — timber, and budget honestly for its upkeep.
Standard residential, most of India — uPVC. Thermal performance without additional treatment, no corrosion, stable through monsoon cycles.
Coastal residential — uPVC, with attention to hardware grade rather than the frame.
Very large commercial spans — aluminium, thermally broken, where stiffness genuinely outweighs conductivity.
Industrial or utility, no thermal requirement — steel remains defensible where insulation is irrelevant and maintenance access is easy.
Why doors follow the same logic
Doors face the same comparison with the loads increased. A door takes more physical force than a window, opens and closes thousands of times a year, and carries its own weight on hinges throughout.
The material failure modes are identical — timber swells and needs repainting, steel rusts, aluminium joints loosen — but they appear sooner because the use is harder.
What changes for doors is that reinforcement and hardware grade matter even more. The section behind the lock has to resist force, and the hinges carry the leaf. A uPVC door with proper steel through the frame and leaf, and hardware specified for daily use, will outlast several sets of hardware without the profile itself needing attention.
The honest summary
No material is best at everything. Timber looks better and needs more. Steel is strong and corrodes. Aluminium is stiff and conducts. uPVC insulates well and needs reinforcement for span.
For the majority of Indian residential openings, uPVC's combination — low conductivity, dimensional stability through monsoon cycles, no corrosion, no pest risk, welded corners and minimal maintenance — matches the conditions better than the alternatives.
Where that combination is not what a project needs, one of the others will be the right answer, and it is worth knowing why rather than defaulting.
Frequently asked questions
Which window material lasts longest in Indian conditions?
It depends on what counts as failure. Timber fails by seasonal movement working on seals and joints; steel fails by corrosion; aluminium fails at mechanical corner joints and at breached coatings. uPVC's failure mode is hardware and gaskets, all of which are serviceable without replacing the window — which is the practical distinction.
Is steel still a reasonable choice for windows?
In industrial and utility applications where thermal performance is irrelevant and maintenance access is easy, yes. Mild steel is strong and inexpensive, but it conducts heat readily and rusts without sustained anti-rust treatment, which makes it a poor choice for residential openings where comfort and running cost matter.
How do window materials compare over twenty-five years?
Purchase price ranks them roughly as mild steel cheapest, then untreated aluminium, then uPVC and timber comparable, then thermally broken aluminium. Whole-life cost reorders them substantially once repainting, pest treatment, anti-rust work and coating repair are included — which is the argument for asking about maintenance before comparing quotations.
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