Steel vs Aluminium Windows : What You Need To Know

• June 3, 2025
• General

When it comes to selecting windows for your home or commercial project, the choice between steel and aluminium can significantly impact aesthetics, performance, and budget. In other words, the steel vs aluminium windows decision plays a major role in how your property looks, feels, and performs for years to come. You might also see this comparison written as “steel vs aluminum windows”, but the key principles remain the same.

At Lightfoot Windows, our team has decades of experience in installing steel and aluminium window systems, and we’re here to help. Whether you’re an architect, developer or homeowner, we have the expertise needed to help you make an informed decision that balances style, performance and budget.

This guide will help you understand the key differences between these popular window materials and determine which might be the better choice for your specific requirements in any aluminium vs steel windows comparison.

Steel vs aluminium windows: which is best?

Both steel and aluminium windows offer sleek profiles and contemporary styling, but they differ considerably in terms of properties, performance, and price. Steel is exceptionally strong and allows for ultra-slim frames that maximise glass area, while aluminium provides a lightweight yet robust alternative that’s highly versatile in terms of design. Whether you’re renovating a period property or designing a modern space, understanding these distinctions is essential for making an informed decision that balances appearance, functionality, and long-term value.

At a glance: the benefits of steel and aluminium systems

Both materials offer significant advantages over alternatives like uPVC.

The unmatched tensile strength of steel allows for very slim sightlines while maintaining exceptional durability and longevity. Well-maintained steel windows can often last 60+ years. The inherent strength of steel also provides excellent security and very good fire resistance. Stylistically, the timeless aesthetic of steel windows suits both period and contemporary properties. Steel windows are also hot-dipped galvanised prior to being powder coated, providing excellent corrosion resistance when correctly maintained.

Aluminium windows also provide impressive corrosion resistance, which is particularly important in coastal areas. Lightweight yet strong, aluminium places less stress on building structures while remaining virtually maintenance-free and requiring only occasional cleaning. Aluminium is highly recyclable, giving it excellent sustainability credentials. A cost-effective solution that doesn’t compromise on quality, aluminium also allows for versatile design possibilities across both traditional and modern schemes.

Both materials allow for generous glazed areas that maximise the amount of natural light entering your property, creating brighter, more inviting spaces and enhancing views.

Cost differences

One of the first considerations for most projects is budget, and there’s a notable difference between steel and aluminium when it comes to initial investment.

Steel windows generally command a higher price point, reflecting their premium status, exceptional strength, and handcrafted nature. The manufacturing process for authentic Crittall steel windows involves skilled craftsmanship and specialist installation expertise, all of which contribute to their cost.

Aluminium windows are typically more affordable than steel. Aluminium frames offer excellent value without compromising on quality or appearance. The lower cost stems partly from the nature of aluminium, its more straightforward production methods, and easier handling on site.

Are steel windows more expensive than aluminium?

While steel windows may require a larger upfront investment, their exceptional longevity often results in strong long-term value. With proper care, steel systems can perform for 60 years or more, which may mean fewer replacements over the lifetime of the building.

Aluminium systems present a more budget-friendly option without sacrificing too much in terms of performance or aesthetics, particularly with our Alitherm Heritage profiles. For shorter ownership periods or tighter budgets, aluminium can be the more practical choice, while for longer-term investment, steel may be more attractive over the full life of the windows.

Thermal efficiency

With rising energy costs and current building regulations focusing on sustainability, thermal performance plays a crucial role in window selection.

Modern steel windows like our Crittall W20 TE range incorporate advanced technology to minimise heat transfer. While traditional steel has historically had lower thermal insulation properties, contemporary steel frames now offer impressive energy efficiency that meets or exceeds building standards. The W20 TE range can achieve a U-value as low as 1.4 W/m² K, delivering excellent thermal performance for a steel system.

Aluminium window frames would normally conduct heat, but modern aluminium windows feature sophisticated thermal break technology that dramatically improves their insulation capabilities. Our aluminium casement windows deliver excellent thermal efficiency, helping to maintain comfortable indoor temperatures throughout the year.

Both materials can achieve impressive energy performance ratings when properly designed and installed. In practical terms, both modern steel and aluminium windows can significantly reduce heat loss compared with older, single-glazed units and help homeowners manage heating costs while maintaining comfortable indoor environments.

Customisation options for steel vs aluminium windows

The ability to personalise your windows to complement your property’s character is essential.

Steel windows offer timeless elegance with distinctive slim sightlines that cannot be truly replicated. Steel frames can be finished in virtually any RAL colour to suit traditional or contemporary aesthetics, including the iconic black finish that defines the industrial look of genuine Crittall windows.

Aluminium windows are also highly versatile in terms of design and colour options. Our aluminium frames can be powder-coated in an extensive range of finishes, including popular anthracite grey and classic white. Modern aluminium systems can be crafted to mimic the appearance of traditional sash windows and other period styles while still delivering a clean, contemporary feel.

Both materials offer excellent opportunities for customisation in terms of glazing style, hardware options, and configurations, allowing you to achieve the precise look and functionality you desire from your steel vs aluminium windows.

Which is better for my project?

The ideal material depends largely on your specific project requirements and priorities:

Consider steel if:

• You desire the distinctive, slim sightlines that only steel can provide
• Maximum strength and security are top priorities
• You’re working on a conservation or listed property where steel replacement windows would be historically appropriate
• You appreciate the unique style and authenticity of genuine Crittall windows

Consider aluminium if:

• Cost-effectiveness is important without compromising quality
• You require excellent thermal performance from a modern system
• Lightweight frames would benefit your building’s structure
• Minimal maintenance is desired for a busy lifestyle
• You want a wide range of standard colour and design options

Why choose Lightfoot windows for your project?

As a premier UK Crittall windows supplier with decades of expertise in both steel and aluminium systems, Lightfoot Windows offers unparalleled knowledge and craftsmanship. Our specialist status within the Crittall network means we provide authentic products installed to the highest standards. We also offer:

• Expert, honest guidance to help you select the perfect material and specification for your needs
• Showroom displaying both steel and aluminium options so you can compare sightlines and finishes in person
• FENSA-accredited installers to ensure compliant, high-quality installations

We understand that choosing between steel and aluminium involves balancing aesthetics, performance, and budget. Our consultative approach ensures you receive informed advice tailored to your project’s requirements, rather than a one-size-fits-all recommendation.

Premium solutions for your next project: contact Lightfoot Windows today

Whether you’re leaning towards the timeless elegance of steel or the modern versatility of aluminium, Lightfoot Windows is here to help you make the right choice for your home or project.

Contact us today to discuss your requirements with our friendly experts. Complete our online contact form, call 020 8662 9090, or email general@lightfootwindows.co.uk
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Want to get a quick estimate on new Crittall windows? Simply visit our ‘Get An Estimate’ page, fill out the required information and one of our friendly experts will get back to you within 48 hours.