A complete guide to aluminium vs steel windows

Looking for heritage, Art-Deco or steel-look windows for your property project? The choice between aluminium and steel windows depends on many different factors, and both materials offer you outstanding new or replacement windows. However, the best product choice depends on some very important considerations too. Aluminium is the better option based on prices and product flexibility. Steel can be the better choice for certain types of properties where only the original material is suitable. When comparing aluminium vs steel windows, where they are being fitted is also important, for example, replacing existing steel windows, want to replace old plastic or wood windows and for a new building project or extension. Our guide to choosing between aluminium vs steel explains all you need to know.

Aluminium vs steel windows – which is best for you?

steel look black aluminium window in article comparing aluminium vs steel windows

Unlike choosing steel or aluminium for interior doors, based on styling, sightlines and what will work best inside the home, exterior windows and doors have altogether different considerations because they come with different expectations.

You will want your new or replacement windows to be secure, energy-efficient and functional. The distinctive design only this style of glazing creates is also vital in giving your property the right look and feel.

Are aluminium windows cheaper than steel?

In the vast majority of cases, buying aluminium steel-look windows will cost you less than steel windows. This is due to how steel windows are made compared to aluminium, with a more expensive welded construction than aluminium’s mechanical construction. Rest assured, quality steel-look windows and doors such as our own Exterior Collection are largely crafted by hand and with a meticulous hand finishing and final inspection process. Whilst aluminium windows will cost you less than steel, choosing the right aluminium product from a specialist and dedicated manufacturer of this style of glazing promises a similar exemplary fit and finish. Price is a key factor when comparing aluminium vs steel windows.

Aluminium windows help keep your project on track

You will find the lead times for aluminium windows shorter than for steel. If your project is on a tighter schedule, aluminium will let you complete your project faster, even with a special colour finish.

A more complete range of products with aluminium

Aluco steel-look bifolds in black in a luxury kitchen
You will not find bifold doors or sliding doors in steel, only in aluminium.

The significant advantage of choosing aluminium when comparing aluminium vs steel windows is the availability of other products with the same steel look. Both aluminium and steel products offer exterior single and French doors to match your windows. However, if large patio doors such as bifolds or sliding doors are part of your design, these are usually never available in steel.

Choosing the right material is essential when your design involves doors designed to connect your home to your patio area or garden and opening up your entire door aperture. Bifolds work best and are available from us with one of the best slimline and steel-inspired folding sliding doors. A considerable factor when comparing aluminium and steel windows and doors.

Aluminium vs steel windows – which is slimmer?

One of the reasons to compare aluminium and steel windows is because only these two window materials give you the thinnest possible windows. Using one of the best known steel window brands, with typical frame profiles as an example, here’s how an Aluco steel-look aluminium window compares. Our representative example is based on an Aluco window with standard profiles into new build openings.

Aluminium windows

Typical frame sightline with vent 58mm

Typical frame sightline fixed light 33mm

Glazing bar sightline 20mm or 25mm

steel windows

Typical frame sightline with vent 53mm

Typical frame sightline fixed light 36mm

Glazing bar sightline 19mm or 23mm

Therefore, the advanced design of Aluco aluminium windows provides an excellent alternative to the typical sightlines of one of the best known brands of steel windows, meaning you can choose aluminium over steel with confidence.

aluminium vs steel windows – specifications

Thanks to current Building Regulations and strict standards on profile and colour quality, glass, hardware and window components, both aluminium and steel windows are designed to last and enhance a property. Both come with excellent specifications, giving you a fantastic user experience with windows that are built to last and a genuine investment in your home.

Here are some of the similarities and differences when it comes to the general specifications and performance of aluminium and steel windows.

aluminium windows

Multipoint Locking – standard

Window Energy Rating B

Matching French Doors

Security Tested

Weather protection tested

steel windows

Multipoint locking – extra cost

Window Energy Rating B

Matching French Doors

Standard locking not security tested.

Weather protection tested

Are you replacing existing steel windows?

Aluminium provides an ideal replacement window solution if your property has existing steel windows. Assuming your property is not in a conservation area or listed, there is no reason why aluminium cannot provide similar styling, slim sightlines and the instantly recognisable grid-like pattern, thanks to the slim glazing bars, mullions or transoms. And you get the same great features inside with a fantastic choice of period, contemporary or Art-Deco-inspired handles and window accessories, just like period metal windows.

Original metal windows are usually much slimmer than new aluminium windows because of their solid frame with no thermal break and single-glazed design. As a result, aluminium windows will give you similar styling but frames that will always be a little thicker. The benefits of slightly thicker aluminium frames are better security, improved energy efficiency, lower heating bills, and vastly improved weather performance.

When replacing existing metal windows, the surrounding frame is also a factor. Original steel windows are fitted direct to the brickwork in stone mullions, stone surrounds or timber subframes. When comparing aluminium vs steel windows for this kind of window replacement, aluminium can work perfectly as a window replacement.

Replacing existing steel windows – is your property listed or in a conservation area?

If your home is listed or in a conservation area, you’ll need to seek advice from your Local Authority. Often the requirement is to replace the outgoing windows with exactly the same windows, in which case only steel will do.

If your Council or Local Authority is happy to consider aluminium windows, we can help you with drawings, window samples and other information, so do get in touch for expert help and advice.

For listed buildings with significant constraints on improving the existing windows, your only options will be specialist steel window refurbishment or the fitting internally of secondary glazing.

Colour options – aluminium vs steel windows

Both aluminium and steel windows provide substantial colour options with virtually any RAL colour. Special colours, and metallic finishes are also available with both products, even if made to order. Remember that smaller independent steel fabricators using their own brand and not a proper system may offer a reduced colour range. Check how the specialist smaller steel fabricators are coating the steel profiles and ensure these are painted by certified and approved colour applicators.

Aluminium vs steel windows and glass options

Just like colours, there is little to choose between aluminium vs steel windows for glass options. Both products provide the full range of single safety glass, textured, patterned, obscure, acoustic or enhanced security.

Aluminium has an advantage with thicker double-glazed units giving better glass performance compared to the thinner units used in steel windows.

Photography/Image Credits: Paul Craig
Photography/Image Credits: Paul Craig and Emma Merry Styling.


Aluminium in the steel look and our own bespoke windows and doors collection promises slim sightlines, the best possible quality, and beautiful colour finishes. We believe Aluco windows will be the last you will ever buy. When comparing aluminium vs steel windows, aluminium prices and lead times are better, and you get a larger range of products, such as bifold doors and front doors.

Aluco Aluminium is proud to design and manufacture some of the best, most authentic and hand-finished aluminium windows, with a unique style, quality and user experience. Made by us and installed by our trained and approved installers, Aluco windows and doors are available at our showroom in Huntingdon or around the country at our approved installer showrooms. Get in touch with us today to arrange a viewing.

Examples of aluco products installed

aluco windows and doors in a barn conversion

Industrial style Barn Doors – Cirencester

An installation of our premium industrial style barn doors in Cirencester Gloucestershire fitted to commercial premises used as a popular wedding venue.  Made from the Aluco Exterior Collection of steel-look doors and installed by L & L Installations Ltd, a very experienced and long-established glazing specialist in Tewkesbury.  Aluco Art-deco, heritage and steel-look doors for commercial ... Continue Reading

Steel look windows in Gloucestershire

Crafted by Aluco and professionally installed by L and L Installations, an expert Aluco and aluminium home improvement company, an installation of Aluco steel look windows in Gloucestershire to a beautiful character cottage. Our sophisticated slimline aluminium windows in the desirable steel-inspired and timeless style, create a fresh new look to this fine home whilst ... Continue Reading

Industrial style French doors in Wiltshire

The potential of an Aluco product to create captivating and focal-point designs is shown in this installation of industrial style French doors in Wiltshire. A bespoke screen spanning floor to ceiling creates a great entrance to a refurbished building use as an estate office in Lushill, Wiltshire. . Grey steel-look industrial style French doors in ... Continue Reading

Buying Guides

Unique features and benefits only with Aluco Windows and Doors

At Aluco, we pride ourselves on leading the way in designing and manufacturing external steel-look doors, windows and screens for your home. Aluco windows and doors come with our reputation for quality, innovation, style and authenticity. Even better, we’ve designed all Aluco windows and doors with several unique features whether as a product or how they’re designed. Here are the unique features and benefits only with Aluco. NO SLIMMER STEEL LOOK DOOR At Aluco, we understand that the beauty of ... Continue Reading

Glazing bars for aluco steel look internal doors, French doors design, showing doors in a brick opening for aluminium vs steel article

Sliding vs hinged internal doors – which is best?

Want to get the perfect interior door for your home or commercial space? You have the choice of sliding vs hinged internal doors, and both provide an excellent internal door solution. At Aluco, we specialise in manufacturing steel-look, Crittall®-inspired, industrial-style internal doors. Sliding internal doors create wide panels and more options when fully open. Hinged doors provide a classic look and are better for standard-size doorways. Here is an explanation of the differences between sliding and hinged internal doors to ... Continue Reading

picture of Aluco aluminium internal doors open with a dog sat between them

How to choose the perfect internal room divider

When it comes to selecting the perfect internal room divider for your home and for a commercial space like an office shop or café, the bespoke nature of Aluco internal doors and screens provides the best possible solution because of its fully bespoke and customisable nature. We’ve created our comprehensive buying guide to help you understand how our crafted and hand-finished internal room dividers offer you fantastic choices of designs, sizes, colours, and glass options. We will also explain why ... Continue Reading

Architectural glazing solutions blended with precision engineering to transform your living space into something truly extraordinary...

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National Coverage

Aluco Aluminium products are installed and supported by a national network of installers.

Reputation WindowsReputation Windows
12:27 19 Dec 23
Exceptional products, high end finish.The team at Aluco are fantastic, always helpful, quick to respond & offer support from quoting through to install.
Josh LumbardJosh Lumbard
09:26 18 Dec 23
Brilliant customer service from Kieran, very helpful and went out his way to provide us with a replacement part that was damaged during installation. Very satisfied with the quality and design of the doors we purchased
Alex AppletonAlex Appleton
08:52 19 Sep 23
We wanted to invest on a quality set of doors as one of the main focal points in a rather large extension of our home. After doing some research we settled on Aluco. Our contact from start to finish was Kieran, who was so helpful, constructive and knowledgeable. When installed we were so pleased as the fit was perfect, the finish outstanding. Not only did we consider the quality better than other options we looked at, the cost was nowhere near them. So much that our window/door fitters that we used on the job are now looking at them as an alternative. A solid 5 out of 5 and would definitely use again.
Andre HessAndre Hess
16:04 07 Aug 23
Great quality aluminium internal doors and quick professional service. Very happy with the products and buying experience. Kieran is super helpful!
john watsonjohn watson
20:53 01 Aug 23
After having a horrible experience with another company, we got in touch with Aluco and they couldn’t have been more helpful. As we are doing a self build, they helped us pick the right doors for the look we were after and to make the best use of our available space. We knew the doors and windows are a top quality product and couldn’t be more pleased with them when they arrived. Everyone we spoke to went out of their way to help and we felt they took a personal interest in resolving our predicament, so it’s a five star review from us for both the service and product.
15:14 22 Mar 23
Just completed house renovation, using all the internal bespoke doors with glass panels. Absolutely delighted with the quality of doors and service. I was assisted every step of the way in getting the right size and format of extremely tall door. Keiran has been exceptionally helpful to deal with over the months from ordering to completion. 10/10I never usually do reviews but but I would say the whole experience and end result that has been achieved has been amazing.
Sarah PattersonSarah Patterson
15:28 13 Mar 23
So pleased with our new Aluco bifold doors, the best we could find on the market! We wanted bifolds with maximum glass area and no bulky frame and the Aluco doors were the perfect choice. Stunning, deep matte black colour, high quality, great choice of hardware and a first-class service. Highly recommend!
Michael HanksMichael Hanks
12:56 10 Mar 23
I've been looking for sometime to find a professional company to fit my new windows and doors and I'm so pleased I found you guys! - Aluco's products are 1st class and so easy to arrange, I just called Aluco, spoke to a very helpful lady who put me in touch with my local installer. I would definitely recommend this product & company :o)
Pauls Mc CrarrenPauls Mc Crarren
10:15 10 Jan 23
I recently had 3 sets of ALUCO exterior crital styled steel framed doors fitted to my property as part of an ongoing renovation. After looking around at various options Aluco was the only manufacturer that I felt could deliver the style I was looking for. With most other companies I thought the design was bulky and not finished to the finesse Aluco has achieved . Based on my experience I can honestly thoroughly recommend this manufacturer and will look to use them again on any future projects
Richard HansonRichard Hanson
09:42 20 May 22
Aluco is leading the way in steel look windows and doors, they are high quality, competitively priced and offering excellent external and internal ranges. We are extremely happy to supply their products to our valued customers.