Comparing Aluminium vs. steel windows

Many homeowners get in touch asking for help and information to change their old steel windows with a credible aluminium alternative. The steel window replacement market is growing, with the majority of aluminium systems companies providing a steel replacement version of their aluminium window systems. When it comes to comparing aluminium vs. steel windows, which is best?

The history of The Crittall Window Company Limited and the Crittall® range of windows is well documented. Not only are Crittall the oldest window company in the world, but their range of steel windows and doors is also still widely used in residential and commercial property.

If you are thinking about replacing your old steel windows, we take a look at the key differences between a steel window such as those made by Crittall and the aluminium alternatives.

aluminium vs. steel windows

Aluminium vs. steel windows.  Why compare the two materials?

Many homeowners love the look of steel windows and want to recreate the metal window look in their home. We have worked with clients that have replaced their windows and doors and even provided New York style screens inside their homes. All of these products were made of aluminium. However, there is a strong argument that nothing beats the look, feel and manufacturing expertise of an authentic steel window. The reality is, as good as aluminium steel replacement windows can be, they will not possess some of the features found in a steel window. It makes sense therefore to compare aluminium vs steel windows and see what each can offer the customer.

For homeowners looking to change their steel windows with a suitable alternative, it is worth researching what both materials can offer so they can come to an informed decision.

How much do aluminium steel replacement windows cost?

Aluminium steel replacement windows will be cheaper than their steel counterparts. On price alone, aluminium as a steel window replacement is cheaper and within the budget of most homeowners. However, it is important to understand why steel windows are much more expensive. Much of this comes down to the entire manufacturing process that is very different to aluminium. Steel as a raw material is also more costly.

Comparing aluminium vs. steel casement windows.

Taking a typical steel and aluminium casement window there are several differences between the two. However, let us first dispel some of the myths about modern steel windows. Today’s steel windows are:

  • Incredibly secure utilising a variety of locking methods and passing current security tests with excellent results.
  • Thermally efficient to meet current Building Regulations.
  • Available as double glazed and fully weather-stripped windows with insulation.
  • Available in the full range of RAL, Syntha Pulvin and BS colours as well as other special finishes you cannot get in aluminium.
FeatureModern Steel WindowAluminium Steel Replacement WindowOriginal Steel Window
GlazingDouble GlazedDouble or Triple GlazedSingle Glazed
Strength3 times stronger than aluminium3 times weaker than steel3 times stronger than aluminium.
SecurityMeets all current standardsMeets all current standardsBasic locking
ManufacturingFully welded windowCrimped and mechanical jointsFully welded window.
Traditional HardwareYes mostly welded to the windowYes, mostly screwed or riveted to the window.Yes
Narrow Sight LinesSteel can be slimmer than aluminium.Aluminium is not as slim as steelSteel can be slimmer than aluminium
Life Expectancy60+years excluding paint finish.30-40 years excluding paint finish.Crtittall windows still functioning in buildings since the 1920’s
Thermal PerformanceMeets Current requirements.A Rated Windows AvailableN/A
Colour choiceFull RAL availabilityFull RAL availabilityLimited choice.
Dual colour optionYesYesNo
Rust ProtectionYesAluminium does not rustNo
AvailabilitySpecialist CompaniesAnyone can fit aluminiumSpecialist Refurbishment only
Modern or Traditional ProductsYesYesN/A
Large Open SashesVirtually unlimited large sizes.Typically 3m2 maximumVirtually unlimited large sizes
Curved heads and Curved on planYesYesYes
Fire Rating of the frameTypically 30 minuesNo fire ratingN/A
Residential and Commercial UseYesYesStill in use today

Aluminium Steel Replacement Windows Key Features.

  • The more cost-effective option.
  • Can be triple glazed.
  • Offers better acoustics if required.
  • More widely available.

Steel Windows Key Features.

  • Aluminium is not as strong as steel
  • Slimmer and enables bigger opening doors and windows.
  • Fully welded construction.
  • Longer Lifespan
  • Available through specialist installation companies.

Both Steel and Aluminium windows deserve their place in the market.

Many people have a negative perception of steel windows, and it is important to present steel in a positive light. Study our table, and you will see they are just as good as aluminium.

It is up to the homeowner to make the best decision on aluminium vs. steel windows, based on their budget and requirements. However, the old perception of steel windows being single glazed, draughty and unsuitable for residential use is no longer valid with the current range of products. Aluminium is an excellent alternative, but steel provides some useful features as well.

Images show Smart Systems Alitherm Heritage 47 windows, manufactured and supplied by Everglade Windows of Middlesex.

Crittall® is a registered trademark of Crittall Windows Limited and is unconnected to the Aluminium Trade Supply Website.

Published on July 9, 2017

Reader Interactions


  1. ed says

    What is the price difference? How much more expensive is a basic steel window over the same size aluminium ? We understand steel is more expensive the manufacturing process and fitting is more intensive but please give us an idea, are they 50% or 300% on average more expensive?

    • Nick Dardalis says

      Hello Ed.
      It depends on who is providing the windows, whether they are making them or buying them in, profit margins and other factors. Always best therefore to approach a few companies for a price and get comparable quotations.

      Kind regards

  2. Nikki says

    Hi Nick,

    Does steel have a multi point locking system, I am told aluminium is more secure because of the 5 point locking system and only one point on steel. Is this correct?

    • Nick Dardalis says

      Hi Nikki, yes modern steel windows depending on the brand/system do come with multi point locking. The more important thing is what security testing the windows have. It doesn’t matter whether they have five point locking or two point locking if they have both been subjected to the same test and passed it. As far as I know modern Crittall® windows do have very good security as a steel window as do others.

      Hope this helps

      Kind regards

  3. jim says


    which would be recommended for homes in a coastal location-say approx. 800m from surf beach, and 300m from closest point of interior boat marina?

    Thanks and Regards, Jim