Comparing Aluminium vs Steel Windows

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Nick Dardalis

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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.

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16:42 30 Oct 23
Nick responded incredibly quickly to my enquiry (on a Saturday too!), and was able to offer invaluable advice on both aluminum systems and manufacturer / suppliers. Thanks Nick!
chris steerchris steer
16:18 09 Oct 23
Had a meeting with Nick during the grand designs show. Was extremely helpful and professional would highly recommend
Chris WesthorpChris Westhorp
19:55 13 Sep 23
Extremely helpful with pointing us in the right direction to find the products we required and suggesting firms that could reliably fit them.Nick was quick to reply and very detailed in his advice.Highly recommend reaching out to them.
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07:03 11 Sep 23
Update - A second email to nick for help on bifolds resulted in a detailed informative reply even on a Sunday ! This guy is so knowledgable and helpful .I approached Nick for an independent view on sliding doors v bifold and the different brand options . His reply was extremely detailed and prompt and allowed me to navigate this often confusing world in a much more informed way . Thanks so much Nick
Anthony CraigAnthony Craig
12:45 05 Sep 23
This is a must site for anyone looking for advice. Great service and very quick answers to questions. Nick has been of great help quiding us through the maze of aluminium products. Thank you
Philip DuffieldPhilip Duffield
20:24 26 Jul 23
I contacted Nick @ ATS for guidance on what aluminium sliding door systems would be suitable for an opening in an extension that is going to be both wide and tall. He came back really quickly with very detailed and incredibly helpful advice. He is clearly extremely knowledgeable about the systems on the market and their respective features and capabilities. If you’re feeling a bit lost by the overwhelming range of choices out there, I’d definitely recommend contacting him.
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17:25 19 Jul 23
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07:51 12 Jul 23
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09:24 16 Jun 23
Fantastic website full of valuable and pragmatic advice about product selection and comparison: no other website gives information like this. Truly written for public interest. Don't hesistate to reach out to Nick via the mailing system. He responds very quickly, is friendly, and has very sound and high knowledgable advice. I have already shared this with my friend planning her own grand design.
guard Charlieguard Charlie
12:28 14 May 23
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Benjamin LewisBenjamin Lewis
10:06 04 May 23
Nick is very helpful indeed. Extremely knowledgeable on bifolds which was in relation to my query. Great website as well, some very useful articles. Particularly appreciated the article that lists all the major bifold options in order of their sightlines! Thank you!
P JonesP Jones
08:07 15 Apr 23
I asked Nick some questions about an installation we were considering and he replied within hours with some very useful suggestions that will probably lead us to using a different make and supplier. Thanks, Nick. Great work.
Nicholas WallNicholas Wall
13:18 02 Apr 23
Looking for fair and honest expert advice on all aspect of aluminium windows and doors? These guys will arm you with all the information you need to make the RIGHT choice in a highly complex, crowded marketplace. post a question and you will get a very quick professional answer you can rely on being based on fact. Thanks guys!
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16:25 21 Mar 23
After a lot of research to find doors that would meet our unusual size requirements and feeling increasingly uncertain about the best way to spend our small budget, I stumbled on the ATS website, and I'm so glad I did! I contacted ATS to request advice and Nick promptly replied with a wealth of information, providing us with options and relevant contact details. I only wish I'd found them sooner!
Carol NortonCarol Norton
10:01 17 Mar 23
I've been so confused about how to achieve the look I'm after, and going round in circles with various window/door companies, trying to get away from the huge chunks of plastic currently around my windows. I didn't expect an email to a company found through a Google search to really help - but I was desperate, so I tried. I'm SO glad I did. Finally I have clear explanations from ATS of where I've been going wrong, exactly what I'm looking for, and a list of local companies that might be able to provide it! The response has excelled my expectations and I feel as if I'm finally inching closer to a home with which I'll be happy and comfortable: thank you.
David NunnDavid Nunn
20:54 14 Mar 23
It is rare that I write reviews, however after my very positive communication with Nick - enquiring about suitable slim sash aluminium windows for my project, I felt that a review was definitely warranted. I can reinforce the many positive reviews posted so far, Nick was very quick to respond, providing comprehensive detail, with excellent independent advice.In summary, great service, thank you Nick.
Chantal AuerbachChantal Auerbach
13:04 09 Mar 23
Nick from Aluminium Trade Supply was incredibly helpful informative and pleasant to deal with. He responded quickly to emails and was very knowledgeable. Highly recommend being in touch with Nick if you are considering new aluminium windows or doors.
Lee JonesLee Jones
20:21 22 Feb 23
I dropped Nick at Aluminium Trade Supply an email re high security slim sightline bi-folds and their alternatives and he responded that quickly (and so comprehensively) that I felt bad I’d not paid him for his time!Nick Sir your product knowledge is outstanding and you are providing a level of service that goes wayyyy above and beyond expectations. I’ll definitely make sure I mention Aluminium Trade Supply to anyone I encounter looking for a fenestration solution 🙏🏼
15:13 13 Feb 23
We are looking to replace some old UPVC patios doors with aluminium ones. The ATS website is a great source of advice in an area where clear information is sorely lacking. Having used the website, I then followed this up with a number of specific questions relating to our search, and Nick came back very quickly with clear, detailed and very useful advice.I have been very impressed with both the website and with Nick's advice. My only regret is that I didn't come across ATS before replacing various windows in 2021 - I'm sure it would have saved me a lot of grief and money! Thanks again Nick.
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17:47 01 Feb 23
So impressed with this company.Responded to my query quickly andgave valuable advice. Nick was extremely helpful and we were able to move forward with our project.
Adri LoloçiAdri Loloçi
11:21 08 Jan 23
Nick was super fast to respond and provided some great recommendations. I would recommend this website to anyone looking to find bifold or sliding aluminium doors.
Stephen HoustonStephen Houston
16:16 03 Jan 23
Looking for aluminium crittall style internal door and external patio French doors. Noted good reviews and thought would ask for advice. Comprehensive reply with excellent independent advice and lists of fitters who could provide products and installation. Great service.
Inga GeachInga Geach
08:25 21 Dec 22
Nick from Aluminium Trade Supply has been extremely helpful with navigating the jungle that is aluminium glazing for our upcoming extension project. His advice was prompt, detailed and always impartial. Very grateful for your input, thanks Nick!
Amanda BurtonAmanda Burton
10:54 16 Dec 22
Brilliant website and an excellent service. Nick provided not only detailed advice and supplier contacts, but highlighted the considerations of various products so I could make an informed choice. Our Sunvista minimal sliders were fitted this week and I couldn't be happier, stunning. Thanks once again for your advice and recommendations, invaluable!
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17:18 10 Dec 22
Very helpful advice given to my question, including the name of 3 different companies that i could try for the product being enquired about. Many thanks
Munim ChowdhuryMunim Chowdhury
11:45 13 Sep 22
Nick has been very helpful on signposting me to a number of partner organisations for steel/aluminium doors.
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17:26 31 Aug 22
My experience with this firm was exceptionally good and this is notalways the case as a female, dipping a toe into technical waters.I was spoken too with courtesy and at a level that helped me consolidate what was needed .On top of that I was given a list of companies and places where I could obtain the type of product I needed.I could not thank them enough and would certainly go there again and reccommend others do too.
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22:39 22 Aug 22
Contacting Aluminium Trade Supply is like contacting the Oracle direct. Advice is always comprehensive and balanced. On multiple occasions they have provided me with options that fully meet our objectives. Many thanks.
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20:25 14 Aug 22
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