There are many benefits associated with installing secondary glazing within your home or commercial property. For example, it can provide you with enhanced thermal insulation, stopping heat from escaping the home and lowering your energy bills consequently. If you live in a noisy area, they can also improve noise insulation, allowing you to get a good night’s sleep.

However, while the question as to whether or not you should install secondary glazing has a clear answer (yes), it can sometimes be difficult to determine which kind of secondary glazing is best – glass or acrylic.

In this article, we’ll dive deeper into the pros and cons of both glass and acrylic glazing so that you can make the best possible choice for your property.

What is secondary glazing? 

Secondary glazing refers to the installation of a secondary window fitted on the internal side of the external, original window. The process of installing secondary glazing has a long history, dating back to the 1800s.

While it is often confused with double glazing, as they serve a similar function, they are quite different. For example, when installing double glazing, the original windows often need to be replaced, whereas with single glazing, this is not the case. For this reason, it is a popular choice of installation for those looking to protect the integrity of period or listed buildings. After all, this means that you do not need to make any alterations to the property as a whole, ensuring its original character and charm remain. This also ensures that you act in accordance to all government regulations regarding the management and preservation of listed properties while ensuring it remains a hospitable space.

As touched upon above, there are many benefits associated with installing secondary glazing panels in your residential or commercial property. For example, in addition to their heat and noise insulation properties, they can also help with condensation control. This is because secondary glazing “actively reduces the development of condensation on both the primary and secondary windows,” which stops condensation and steam from clouding your windows and ensures their longevity. 

Overall, secondary glazing can create a more hospitable living environment within your home. For example, improved heat control often means that you can keep your home at a nice temperature throughout both the summer and winter months. This, in turn, often means better sleeping habits and improved immunity and health. As such, secondary glazing is an excellent way to transform your property for the better and could also add significant value to your home. 

Image of a Windows with the sun light shining through it

Photo by Amel Majanovic on Unsplash

What are the best materials for secondary glazing? 

Secondary glazing can be made with a wide range of materials. Frames can be PVC , Aluminium  or timber and the frames can be glazed with either glass or acrylic. However, glass and acrylic tend to be the most popular choices among property owners. 

Of course, the choice of which glazing you choose is dependent upon a variety of factors, from the property you are working on to your budget. 

Glass Secondary Glazing

Glass is the more traditional option for those looking into secondary glazing – however, there’s a reason why its use is continued to this day. 

A few different types of glass can be used to create secondary glazing panels, such as laminated glass or toughened glass.

Pros of Glass Secondary Glazing

There are many benefits associated with choosing glass secondary glazing panels.

  • Durable and long-lasting: Glass window panes remain popular due to the fact that they are incredibly durable and long-lasting. While secondary glazing is interior, meaning it is not exposed to the elements, choosing glass panes can still expand the lifespan of your windows/glazing as a whole.
  • Fire-resistant: Unlike acrylic materials, glass is non-flammable. As a result, installing glass secondary glazing can help to protect your property in case of fire.
  • Aesthetically pleasing: Glass secondary glazing has a clean, polished finish. Unlike acrylic, it does not “yellow” or age over time, making it a great choice for secondary glazing. Glass windows do not tend to scratch easily as plastic-based panels.
  • Easy to clean: Glass window panes are relatively easy to clean. As a result, they require very little in the way of maintenance.
  • Glass secondary glazing is more effective for thermal insulation and noise reduction as the glass types are more complex and the result is more effective.

Cons of Glass Secondary Glazing

  • Difficult to install: One of the drawbacks associated with glass secondary glazing is that it is harder to install than acrylic glazing. This is because it tends to be heavier than acrylic glazing.

Acrylic Secondary Glazing

While glass secondary glazing brings many benefits to homeowners, many property owners choose to install acrylic secondary glazing instead.

Acrylic glazing is typically made from several sheets of a type of thermoplastic known as PMMA (Polymethyl Methacrylate). PMMA is used for this purpose as it is a lightweight, shatter-resistant material.

Pros of Acrylic Secondary Glazing

There are many benefits associated with choosing acrylic secondary glazing panels.

  • Lightweight: Acrylic secondary glazing panes are lightweight, which makes them relatively easy to install when compared to glass secondary glazing panes, which may require professional installation. As a result, many people find that this is an excellent DIY project, though it is often far better to bring in the experts to assist you on this task. 
  • Shatter-resistant: According to various studies, acrylic sheets or panes are 17 times more shatter-resistant than glass. As a result, they are less likely to shatter on impact, which makes them an excellent choice for high-traffic or busy areas. 

Cons of Acrylic Secondary Glazing

  • Difficult to maintain: While acrylic secondary glazing panes are shatter-resistant, they are more prone to scratches than glass. As a result, many property owners find them difficult to maintain.
  • Prone to yellowing: Unlike glass, acrylic is prone to yellowing over time. This is caused by exposure to the sun and UV rays. As such, acrylic secondary glazing may quickly lose its lustre, meaning that the windows appear cloudy or discoloured. 
  • Less effective for thermal insulation and noise reduction

Glass vs. Acrylic Installation: Costs

When it comes to determining which type of secondary glazing is better, you may also want to take into consideration the cost of each product. While acrylic secondary glazing can be cheaper than glass, it’s important to note that glass secondary glazing has a much longer lifespan, and it will give you a better end result to the problem you are trying to resolve.

As such, while it may be more expensive to begin with, this is a worthwhile investment. It is also resistant to damage, meaning you are less likely to need to replace it. 

Glass vs. Acrylic: Which is better for Secondary Glazing? 

While both acrylic secondary glazing and glass secondary glazing have their benefits, glass is the better option. After all, glass is: 

  • Highly durable, meaning that it is more likely to stand the test of time. It is also resistant to scratches and other signs of visual damage, unlike acrylic, which can scratch easily. 
  • More effective for thermal insulation and noise reduction
  • Heat-resistant, providing you with extra peace of mind and protecting your property in the case of fire or similar events. 
  • Aesthetically pleasing, making them a particularly popular choice among those wishing to maintain the character of older or listed buildings.
  • Relatively easy to maintain and clean, saving you a great deal of manual labour and energy.


What window styles are available? 

When purchasing secondary glazing for your property, it is important to note that there are a wide range of window styles to choose from. This makes it easier than ever to find a product that matches your needs, no matter what kind of renovation project you are working on. Popular styles include: 

Sash Windows

Sash windows are the most common type of window style in the UK and are otherwise known as “vertical sliding sash windows.” When installing secondary glazing to these windows, great care must be taken to ensure that the glazing mirrors the external window so that functionality is not lost.

Horizontal Sliding Windows

Horizontal sliding windows are an incredibly versatile style of windows. At City Sound Glazing, we can install secondary glazing to 2, 3 or 4 sliding panels, depending on your current window style. Both styles of sliding windows are typically found in residential properties.

Fixed lift out

As the name suggests, fixed lift-out windows refer to windows that feature a removal glass panel, which is typically held in place by a master frame. They are perhaps the easiest style of secondary glazing to install. 

Casement (Hinged) Secondary Glazing

This style of secondary glazing is applied on hinged windows or even door frames. It is typically used within clinical settings, though it can serve many other functions. 

Find out more

At City Sound Glazing, we have years of experience when it comes to installing secondary glazing in properties throughout London. Whether you are looking to improve the sound insulation in a city-centre flat or heat insulation in a listed building, we’re here to help. 

If you’d like to find out more about our services, please do not hesitate to get in touch today. We’d be happy to answer any questions you may have, or to assist you in your property renovation project.