Introduction

In this article, we'll explain what aluminium retrofit double glazing is, explore the various benefits it offers and clear up some common misconceptions about aluminium double glazing.

This article discusses retrofitting aluminum joinery, but we also provide services to double glaze existing timber joinery, which you can learn more about here.

What is Retrofit Double Glazing?

Double glazing retrofit, such as Eversure reFIT services, involves refitting existing window and door frames with new double-glazing units. The original glass is removed and replaced with double-glazing units specified to comply with the latest safety standards.

Other window components such as rubbers, catches and stays are also replaced in our reFIT process, and in some cases, we can even update the layout of the windows/doors by removing aluminium profiles, or converting opening windows to fixed windows or vice-versa.

In terms of the actual double-glazing units, Eversure works with high-quality products, consisting of two separate panes of glass, sealed hermetically (airtight) around the edge with a thermal spacer system. The space between the two panes contains either air or argon gas. The glass itself can be tailored specifically to meet the unique needs of your home. You can view our glass solutions here.

Note: Although Secondary Glazing and plastic films are often marketed as retrofit double glazing, these are not comparable alternatives to 'genuine' sealed double glazing units which are now used for all new homes.

How do I know if my joinery can or should be retrofitted?

It’s rare for Eversure to come across joinery that cannot be upgraded to double glazing. However, just because we can retrofit joinery, doesn’t mean it's necessarily the best option. Our consultation process involves our sales team visiting your home and assessing your joinery. For example, if aluminium joinery is nearing the end of its service life, we would often recommend full replacement frames using our reFRAME service.

Benefits of Retrofit:

In most situations, our reFIT Ali service enables our full range of double-glazing solutions to be installed into existing joinery. This means you can achieve major improvements in many different areas including thermal efficiency, noise reduction, fading reduction and security. reFIT of your existing joinery includes replacing worn-out window components and it allows you to upgrade while minimising waste, keeping costs down and retaining the original character of your joinery.

Aluminium Retrofit (reFIT Ali) Installation, how is it done?

We’re going to look at the aluminium retrofit process in three separate parts, fixed windows (non-opening), opening windows, and doors.

Fixed windows:

Most fixed aluminium windows have a beaded glazing system. The glass is secured into a window frame with a combination of an aluminium bead and rubber wedges. Typically, single glazed fixed windows utilise beads that have a 45-degree slope back towards the glass.

The process starts with removal of the old beads, glass and rubbers. New rubber backing seals are then fitted into the frame, before the made-to-measure double glazing units are placed into the frame on setting blocks, so they’re not in direct contact with aluminium. We then fit brand new, colour-matched aluminium beads that are designed with a 90-degree angle instead of the 45. This enables us to utilise the full depth of the joinery and double glazing units sized to optimise the insulation space. Finally, new external rubber wedges are fitted to hold the double-glazing and new beads securely in place.

The Eversure reFIT services include bead solutions compatible with most joinery suites, so even if your joinery is on the older side, it’s highly likely that we’ll have a retrofit solution available. The photo below provides a cross-section, showing a fixed window before and after our reFIT Ali service.

Fixed Window Before

Fixed Window After

Opening Windows:

There are four types of opening windows: awnings, casements, sliding, and bi-folding. Awning windows open by pushing out from the bottom, with stays on the sides. Casements push out from the side, with stays at the top and bottom. Sliding windows open by moving on rollers, while bi-fold windows are hinged on the side and fold back in a concertina style. The reFIT Ali process for sliding and bi-fold windows and doors is the same. This is explained in the Doors section below.

For awning and casement opening windows, we refer to the entire moving panel as the sash. Sashes are usually rectangular captive sashes. This means the sash is assembled around the glass (much like a picture frame) with the glass 'captured' within a pocket formed by the aluminium profile. Rubber wedges are then fitted between the glass and aluminium to hold the glass securely in place.

The sashes connect to the frame using stays, allowing them to swing open and hold their position. Catches on the sash help pull it snugly into the frame when shut. The window frame includes rubber weather seals that the sash closes against. The sash must close tightly against this rubber seal.

The Eversure reFIT Ali service for opening windows includes removing the existing sash, stays and seals, and fitting a brand new opening window sash with new wedges, new seals and new stays and new catches (usually double-tongue for easy ventilation). The colour of the catches and the new aluminium sash will be matched as close as possible with the joinery colour. Additional hardware such as restrictor stays or security stays are optional for opening windows (but will be included where needed to comply with safety requirements).

Doors:

The three main types of doors are hinged, bi-folding and sliding.

Whether they are hinged, bi-folding or sliding, aluminium doors will be either beaded (like most fixed windows) or captive (like most opening windows). Occasionally they may have a hybrid glazing style with a mix of beaded and captive profiles on different sides.

If a door panel is beaded, the reFIT Ali process will be the same as for fixed windows, which you can find explained earlier in the article. For sliding doors, we install new rollers and a new colour-matched handle to ensure the door slides and latches well.

If a door panel is captive, we utilise an adaptor profile fitted into the existing door panel to provide the platform required to accommodate a double glazing unit. Like the new sash and bead profiles, these are colour-matched as closely as possible with the existing joinery. As this profile fits within the existing door panel, there will be a slight reduction in the viewing area (surface area of glass).

The photo below shows a close-up example of an adaptor profile that has been fitted into a sliding door panel. The exact position of the adaptor can vary depending on the type and thickness of the existing sliding door panel, and it won’t always sit flush with the face of the door panel.

Hybrid doors have both beaded glazing and captive glazing so require use of a combination of the above solutions, replacing the old beads with new beads and fitting adaptor profiles into the captive glazed sections of the door.

When reFIT ALI is not possible or desired for a particular door, we can install brand new doors. This can involve either fitting a replacement panel into the existing frame, or utilising our reFRAME Full service to replace the entire frame.

Additional Important Information:

Configuration Upgrades:

With most aluminium joinery suites, the frame that holds both fixed and opening windows is the same. Accordingly, fixed and opening windows are interchangeable, enabling fixed windows to be converted to opening windows (provided they’re within the appropriate size range) or opening windows to be converted to fixed windows.

We can also remove horizontal profiles (transoms) to create larger windows or door panels, which can modernise joinery and improve thermal efficiency.

Drainage:

Aluminium joinery consists of glass, rubber and aluminium and is designed to be 'water in / water out'. It's normal for water will find its way into the window frame between the rubber and glass/aluminium. The joinery is designed to channel water internally to drainage points, so that any water that enters will drain back out.

Faulty drainage can allow water to enter the house framing or the house interior and can also lead to premature failure of double glazing. Accordingly, care and attention to proper drainage function is an important priority for Eversure reFIT Ali installations.

Aluminium Retrofit Double Glazing 2025, an in-depth guide.