Information about replacing Crittall Windows with aluminium.

If you live in a house with old Crittall® windows or other steel casements, what are the options replacing old metal windows with aluminium?  Is it also possible to improve your existing windows for better appearance, security and energy efficiency? In this article, we provide information on what to consider with steel window refurbishment and the aluminium options for replacing steel windows.

Products for the replacement of Steel Windows with aluminium.

replacing crittall windows with aluminium
Aluminium steel-look windows made by Everglade Windows of Middlesex.

If you do want to explore the aluminium options for replacing Crittall® windows,  we have compiled a list of some of the window ranges for you to consider.  It is worth stressing that these are not really “Replacements” as you are not replacing like-for-like.  These aluminium windows and doors are designed to offer an alternative product.  Steel windows remain the best option, providing a different construction, slimmer sightlines and a significantly longer life.

It’s also worth understanding the type of steel windows you’re replacing. Old metal windows have different names depending on when they were made. Windows from the 1920’s may be the type called Universal Range. From the 1960’s you’ve probably got W20 windows installed. There’s also a product called SMW standing for Standard Metal Window.

Smart Systems Alitherm Heritage 47.

The Smart Systems Alitherm Heritage 47 is a remarkably well-designed aluminium window. This window suite creates steel look windows, New York Screens and even has a steel look door.

We have seen many installations using Smart Systems, and it looks great as a slimline aluminium window.  The door, in particular, is excellent for its visual similarity, although again not precisely like a steel door. There are several specialist manufacturers of Smarts Systems Alitherm Heritage 47, one of which is Everglade Windows in Middlesex, Pioneer Trading in Essex, Duration Windows in Canvey Island and other large or small manufacturers.

Smarts Alitherm Heritage.

Smart Systems also offer another steel look window to give similar aesthetics and an aluminium alternative to steel windows known as W20. Called Smarts Alitherm Heritage, this version is widely used in listed buildings, heritage properties and developments where a replica window is required. Alitherm Heritage is made in a modular form enabling any window design to be created using aluminium couplers. Authentic looking beads, drip bars and other profiles complete the look.

Smarts Alitherm Heritage comes as fixed, side or top hung casements, pivot windows and single or double sash windows.

It is worth mentioning that the Smarts Alitherm 600, used as conventional aluminium windows, also gets used in steel-look installations. If the profile sightlines and appearance work for your project, Alitherm 600 is worth considering.  Again we stress these are aluminium alternatives in a similar style, but nothing beats the authentic steel product.

AluK Optio 58BW ST steel replacement

The AluK Optio 58BW ST steel replacement window comes from another leading aluminium systems company.

The slimline profiles enable this window to be used in the home as well as commercially. AluK’s window is designed to replace old steel windows offering very slim sight lines and a credible aluminium alternative with high security and excellent thermal performance.

You can choose between 58mm or 70mm frame depths to suit new build and replacement applications. Other options include double glazed units up to 32mm, excellent security and a choice of what AluK calls Bay, Heritage or Contemporary profile appearance.

Finally, the AluK Option 58BW ST window comes as a fixed, multi-light, casement, bottom hung and multi-light arrangement.

Reynaers CS 24 -SL

Reynaers’ CS24-SL stands for Concept System 24 Steel Look. Windows are casement windows with handsome proportions and another suitable aluminium window to replace old steel windows.

The aesthetics centre around the external sight lines that include sloping glazing beads with a similar look found in old steel casements. The outer frames are only 19mm sight lines and the opening vent sections 31mm. The mullion and transom sections are also thin at just 13.9mm.

You can use the Reynaers CS 24-SL Steel Look window to replace old windows or for new build homes and extensions. They are also suitable for commercial buildings as well. Reynaers CS 24-SL are security and weather tested and even comes with a matching door option.

Reynaers Slim Line 38 aluminium window.

Also available from Reynaers is the SL38 suite of windows offering flexible design options as well as windows that can open in or out.

You have a choice of three different looks with the Reynaers SL38. There is Classic, Ferro and Cubic. Each of these is intended to offer a different visual look to a sliding aluminium window.

Classic offers a sloping detail to the outer frame and the opening sash. Cubic gives you a flat frame and sash. Ferro provides a flat external frame, but the sash features a projecting square nosing. All three are beautiful windows that are entirely different in appearance to the others we mention.

With the Reynaers SL 38, you get excellent weather performance, extensive colour choice, good U-Values and high security. Double and Triple Glazing is also available.

Also recently launched from Reynaers is the Slimline 68 aluminium window.  While not a steel look system, Reynaers SL68 offers very slim frames that would make it ideal for more basic window designs without the many horizontal bars found in metal windows. Reynaers are incredibly well-designed windows and should be checked out with other brands.

SAPA Crown 52mm casement.

While not marketed as a steel replacement window, the SAPA Systems Crown Suite of windows with the slimline vent and square outer frame is an option. We have seen these used very successfully to replace old steel windows, particularly those in hardwood subframes.

The SAPA suite offers a choice of vent, frame and mullion profiles making for a very flexible window to meet most design requirements.

Schuco Window AWS 70.HI

Schuco windows also come in many different styles and options including a slimline steel look window. A Schuco AWS70.HI is a highly insulated aluminium window that creates inward or outward opening windows.

There are four variants available in the Schuco suite such as the Soft Linen Residential Line and Steel Contour. You can mix and match the sections to create a custom window. However, the Steel Contour is the one intended for metal window replacements. It is suitable for new build openings as well. Face widths of the window are 117 mm.

Schuco ASS70 HI windows in steel contour are those specially designed for steel replacements. With the Schuco window, you can expect all the engineering found in their excellent sliding and folding doors. Schuco is also known for windows with low U-Values and excellent security test results too.

Schuco brings automation to their windows giving you a motorised opening option as well, called Schüco Tiptronic.

Replacing old steel windows.

If you can afford the luxury and the price premium, new steel windows are the way to go. New windows will retain much of the authenticity of your outgoing windows and steel specialists can advise, with many having an extensive range of products to choose from.

Is the sunshine bay available in Aluminium?

crittall bay windows
Image courtesy of

If you have old steel windows with one or two curved glazed sides, you may be wondering if it possible to replicate these in aluminium? The answer is yes if your chosen supplier has the skills and the suppliers to do it.

Curving aluminium sections on elevation (to create curved head windows) is much easier than curving on plan such as sunshine bays. Bending the spacer bars that separate the outer and inner pane of a double glazed unit is easy for those with the knowledge and skills to do it. Curved glass is also possible, but you will pay the price for having all these standard sections sent to a specialist section bender.

What you need to do is seek out a specialist company that can create aluminium sunshine bay windows. You’ll find more suppliers of standard windows and fewer that offer curves and shapes. We can help put you in touch with these. The less experienced company will want your work but offer flat glass and angled bays using bay poles. If you wish to the curved window to match your original seek out a company that can do it.

Current Buildings Regulations are sympathetic to period windows.

If you live in a period property, one in a conservation area or with planning constraints, always check with your local Authority or Conservation Officer.

Many local authorities do make allowances for properties with traditional windows or those of historical importance or architectural significance. Always seek professional advice.

Consider fitting authentic Crittall® Windows.

It is worth extolling the virtues of these windows and just how good they are. The fact remains, that while there are excellent aluminium alternatives, steel windows, look different and are different.  Once again, if you want the 100% authentic product, check out the unique windows and doors by Crittall®.

Longevity, construction and appearance are just three great reasons also to consider a steel window.  Some windows are still working today more than 90 years after being fitted.  No aluminium or plastic product has this service life, nor is it likely they ever will.  Steel windows feature galvanised steel, durable finishes, quality hardware and are built to last. Steel windows are also the slimmest.

Steel remains a super durable material giving these windows excellent security even when they are as slimmer than aluminium. Choose a steel window today, and you will get all the style, energy efficiency and high security you associate with a new PVCu, aluminium or timber window. The only drawback to steel windows is their cost when compared to other materials. However, given how long they will last, it is an excellent investment in your home. As well as this, properties with authentic steel windows and also very desirable to prospective buyers.

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A typical house with original steel windows.  Consider replacing them carefully.

Refurbishment of old steel windows.

One fantastic feature of old steel windows is how they work with the overall appearance of a house. Period homes are a favourite with homebuyers because of their character and original features. Windows are one of these. If you want to retain your original metal windows, refurbishment is one option. There are nationwide specialists in the restoration and renovation of steel windows, or you can seek advice and a suitable company from The Steel Windows Association.

Early generation steel windows will not be galvanised and probably worse for wear from corrosion; not helped by many different coats of paint over the years. The window hardware on original windows can be hard to replace if broken, and the putty may have failed as well. We suggest you seek advice from one of the specialists in restoration and get some initial advice.

In considering a repair to old steel windows, security and energy efficiency remain poor by modern standards. There is little you can do to improve it and this will be one compromise.

How can you repair old steel windows?

In deciding whether to repair or replace your old steel windows, your key concerns may be:

  • Improving Security.
  • Improving Energy Efficiency
  • Replacing your old single glass with double glazed units.
  • Reduction in noise levels
  • Improvement in weather resistance.

Depending upon the condition of the existing windows it may be possible to improve them in many of these areas. New seals, new handles, replacement glass and general refurbishment, are all offered by expert companies.

While you will not get the advantages of brand new thermally insulated windows, any good refurbishment provides some improvement over the old windows.

So what are your options for new windows in aluminium?

Secondary double glazing for steel windows.

It is worth mentioning Secondary Double Glazing. Secondary double glazing is an excellent alternative for houses with old metal or single glazed windows.  With secondary double glazing, you will usually find little resistance from conservation officers. Secondary double glazing is also substantially cheaper than new windows of any material.

Modern secondary double glazing is fitted behind original steel windows and is available in fixed, swing, lift-out and even sliding windows, meaning you should be able to retain the authentic look of your windows when viewed from the outside.

interior steel doors

Conclusion and Next Steps.

It is worth mentioning finally that all of the above systems should work well if you need them fitting in stone mullions or hardwood subframes.

All of the above products will give you all the advantages of new double glazed windows that will improve your home over existing steel windows. For us, the Smart Systems Alitherm Heritage 47 and the Reynaers SL24 and SL38 are the more appealing aluminium window residentially.

Installers like Alitherm windows also having a matching Alitherm Door as a single or double door set.

There are other specialist independent companies whose business is aluminium steel replacements. Examples include the Heritage Window Company in London with their Benenden Range, Jennyfields in Hampshire with their great steel windows that also create sunshine bays.

What these companies often do is take an existing system like the Alitherm and tweak it. They work with the systems company to modify the profile to make it different from the standard product and frequently will get exclusivity to it. There’s nothing wrong with this way of creating a more bespoke window. Aluminium systems companies are in the business of selling bars of aluminium and if they can do this for an independent installer, they will.

If you would like more information about steel replacement windows, and where to see them, contact us today. We can help put you in touch with suppliers and installers and answer your questions about replacing Crittall windows with aluminium.

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

Main image shows Smart Systems Alitherm Heritage 47 Windows manufactured and supplied by Everglade Windows in Middlesex


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