A Beginner’s Guide to Secondary Glazing Parts

A Beginner’s Guide to Secondary Glazing Parts

Thinking of warming your home with secondary glazing? Great idea! But admittedly, the myriad of different types and styles can easily become confusing. That’s why we’ve prepared this handy beginner’s guide to help you get to grips with the ins and outs of secondary glazing parts.

So, if you can’t tell your edging from your brush gasket, don’t worry! Read on to discover everything you need to know…

Secondary glazing parts – the basics

First, you’ll need to understand the three core components that make up a secondary glazing unit.

Primary Panel

Secondary glazing is unique because it doesn’t require the removal of your original window. So, you’ll have one of the most important secondary glazing parts already with you – the primary panel, also known as the existing window. This is what makes secondary glazing perfect for listed properties or for windows that you’ve always loved and have no intention of removing.

Secondary Panel

Secondary glazing involves adding a second slim panel of glass to your existing window. This panel can be designed to suit a variety of window styles, including horizontal and vertical sliders, hinged casements, and even bespoke windows.

What’s more, you can also tailor the type of glass to suit your needs. Our standard offering is the 4mm toughened glass, which provides a 50%+ improvement in thermal insulation for your rooms.

Alternative options include Low E toughened glass, which features a thermal performance coating. Or if you’re more concerned about sound insulation, the Stadip Silence 6.4mm clear acoustic should do the job. There are also laminated glass, obscure glass, and satin glass options to meet your privacy and security needs.

There are incredible benefits that come with this second panel (and the gap in between the panels, below), from saving on your energy bills to preventing condensation.

Air Gap

Whilst this might not be a physical secondary glazing part, it is possibly the most important factor of all. Between the two panes of glass lies an air gap, and the wider this gap, the greater its insulating properties. The gap creates a barrier, preventing cold outside air from slipping into your home.

This is especially the case when it comes to sound insulation. If keeping out noisy neighbours is a priority, then we strongly recommend achieving a gap between 100-200mm. For thermal insulation, you’ll need a gap between 50-80mm.

Secondary glazing fittings and accessories

From sealants to tracking, there are many other important secondary glazing parts to be aware of…

Locks and handles

When the summer comes, you need to open your windows wide – and be sure you have a high level of security when they’re closed. That’s why handles and locks are so important. They vary depending on the type of window you have – some windows won’t have a handle at all, but most will have a handle with a lock incorporated in.

Some of the most popular secondary glazing handles include:

  • Cockspur handles – One of the most popular types of handle, this features an easy latch-and-catch system.
  • Espag handles – These feature a spindle at the back of the handle, which slots into the gearbox. Spindle sizes vary, so ensure that you’ve measured it before purchasing a replacement. These are frequently used with casement windows.
  • Tilt and turn handles – Like espag handles, these also feature a spindle and are frequently used with uPVC windows.


In glazing, sealants are used to seal any connections, either between the frame and the glass or the joint between two panes of glass. This prevents moisture from making its way through any small gaps.

Secondary glazing sealants need to be flexible to manage any movement from the frames or panels. They also need to be weather resistant and highly resistant to UV, as this can wear down some sealants extremely quickly. Make sure the sealant you use is compatible with the material of your frames. Generally speaking, though, silicone sealant is the most popular option.


As its name suggests, edging fixes around the edges of the glazing panels to neaten their appearance. One of the most important secondary glazing parts, this fitting covers the gap between the panel and the wall. If the gap is wide enough, there is also the option for edging with a frame attached.


Secondary glazing tracks keep the glass panels in place and serve as a partition between the different panels. There are options for fixed and sliding secondary glazing, so that the glass can move along the track. Horizontal sliders, in particular, make cleaning your glazing a breeze.

Bristle seals/brush gasket

When it comes to secondary glazing parts, you should never overlook the gasket. This is a seal that keeps the glass secure within the metal tracks. It can be made from rubber, but brush or bristle is usually a more insulative material. Gasket seals fulfil a range of purposes, including keeping the panes securely in place, reducing vibrations, providing a weatherproof seal, and insulating the windows in terms of sound and heat.

Frames and subframes

The frame surrounds the secondary glazing, providing support and insulation. It sits between the glazing unit and the wall. Within the frame, there can also be sub-frames, typically made from wood. These provide support and structure to the primary frame.

Fixing clips

Fixing clips can be used with edging to attach a glass panel across an existing window. Once the edging is in place around the glazing, the clips are attached to the edging, then screwed in place onto the existing window.

Secondary glazing installation and DIY kits for your home

There’s no need to be too cold this winter – or too hot in the summer! Secondary glazing parts work together to insulate your rooms from cold weather, sound pollution, condensation and many other issues.

If you’re feeling the chill but don’t want a huge disruption to your home, you’re in luck. With over 20 years’ experience, our secondary glazing installation process is quick and non-disruptive. And if you feel like taking on the task yourself, our easy-to-use DIY kits are the perfect choice.

Ready to get the ball rolling? Email our friendly team at [email protected]. Alternatively, get a free online quote today.


Clearview secondary glazing - the solution to significantly improved acoustic and heat insulation to your property, making your home or offices more comfortable, secure, greener and cost efficient to run. Achieved without the disruption of replacement windows, and without damaging the character of your building.

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