Comparing Aluminium vs Steel Windows

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Nick Dardalis

What are the significant differences when comparing aluminium vs steel windows? Where you need to replace old steel windows or want to add steel-styled windows and doors as part of a property project, steel windows are the genuine article.

Aluminium provides Crittall style aluminium windows made differently, costing less but taking design inspiration from the authentic product. We explain all the differences when choosing aluminium vs steel windows and some advice on what’s best for your project.

Some background on Crittall Windows the Company

crittall style windows in a loft apartment
Steel windows create timeless Art-Deco, Industrial, Heritage of Scandic-style glazing

The history of The Crittall Windows Limited and its iconic steel windows is well documented. Today, the Crittall® range of Homelight, Innervision or Corporate W20 windows provides some of the best and most luxurious windows 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. As a material, steel is top-end.

Adding a genuine steel window by Crittall or any other steel brand promises an altogether different look and feel. You also get the slimmest lines, phenomenal build, fit and finish with premium window and door hardware.

Steel also provides arguably the longest service life of any window material. If the steel window is a genuine Crittall product, you’re also getting one of the best window brands in the world.

aluminium vs steel windows in a modern loft apartment
When comparing aluminium vs steel windows, steel is slimmer, welded and the longest lasting

Aluminium Crittall style windows explained

Only the genuine steel product and brand give you the genuine article. Beware marketing messages such as Crittall Look, Crittall Style or Crittall replacement expecting to get exactly the same result. You’re not getting the same look, style or like for like replacement. What you are getting is a window with a similar overall appearance and feel. The sightlines are a little thicker, aluminium doesn’t come as a fire-rated version like steel can.

For homeowners looking to change their steel windows with a suitable alternative, aluminium still gives you beautiful looking windows and doors, outside or inside the property but never exactly the same.

The aluminium versions of steel windows provide similar lines, a grid-like appearance, the deep bottom rails, similar hardware and the thicker panel behind the door handles. As aluminium steel-look windows aren’t welded the also look different at the joints and are cheaper and faster to make. In aluminium therefore, aluminium windows will cost a lot less. There’s more product information about aluminium steel-look windows.

Even though there are manufacturing and visual differences comparing aluminium vs steel windows, the styling of these remains popular with many homeowners.

aluminium vs steel windows showing an example of aluminium grey windows
Aluminium Crittall style windows in the aïrMOD collection, made by Everglade Windows of London

Aluminium vs. steel windows.  How the two materials compare

The decision on what material is best depends on several factors. These include:

  • Whether the budget stretches to the authentic steel window
  • If windows are required as a replacement of existing Crittall or other metal windows
  • If windows, doors or screens are needed inside or for exterior glazing
  • Any specific planning constraints such as replacing like for like.

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.

Why aluminium Crittall style windows cost less

Aluminium steel replacement windows are cheaper than steel based fir several reasons and there’s more information about typical prices on aluminium steel-look versions.

  • Aluminium is a cheaper raw material than steel
  • The fabrication costs are less with aluminium
  • Wider availability also results in more competitive pricing
  • Powder coating and colouring aluminium can also cost less

Comparing aluminium vs. steel 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 is 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 PerformanceB and C Window Energy RatingsSome A Rated Windows AvailableN/A
Colour choiceFull RAL coloursFull RAL and other finishesAs originally supplied
Dual colour optionYesYesNo
Rust ProtectionYesAluminium does not rustNo
AvailabilitySpecialist CompaniesAnyone can fit aluminiumSpecialist Refurbishment only
Modern & Traditional ProductsYesYesN/A
Large Open SashesVirtually unlimited large sizes.Typically 3m2 maximumVirtually unlimited large sizes
Curved heads and Curved on planYesMore difficultYes
Fire Rating of the frameFire rating available No 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.

  • Steel windows are the 100% genuine article for Art-Deco, Heritage and industrial look
  • Bigger window and door sizes than aluminium
  • Fully welded construction.
  • Longer Lifespan
  • Available through specialist installation companies.
aluminium steel look windows


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.