With secondary glazing, you have quite a bit of choice over the materials you use. uPVC is one option, but you can also get frames made of aluminium and timber. 

So, which is best? 

That’s the question we answer in this post. We run through the pros and cons of each type of frame so that you can better understand which one to pick for your secondary glazing. 

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The Pros And Cons Of Aluminium Secondary Glazing

Aluminium frames were all the rage when the first round of double-glazing products hit the market in the 1970s. However, the use of this material in secondary glazing goes back to the 1910s. People would install additional frames behind their main facade to improve insulation and prevent nasty winter draughts.

Since then, homeowners and installers have become well-versed in the advantages and disadvantages of this frame type. While aluminium has benefits, it also carries considerable drawbacks.

Pros Of Aluminium Secondary Glazing

1. Improved Insulation

Like other secondary glazing options, aluminium frames offer improved insulation. The additional layer traps heat, preventing it from travelling outside and forcing energy bills up. It can also work in reverse – preventing hot summer air from entering your interiors.

Metal isn’t usually a strong insulator. However, aluminium has other benefits, including being lightweight and malleable, making it less prone to cracks.

2. Reduced Maintenance

Aluminium secondary glazing is also low maintenance compared to wood. It can last years in direct sunlight and doesn’t require repainting every few years.

Because of how the metal works, it also resists warping. Frames won’t change shape over the years, avoiding costly replacement.

3. Improved Fire Resistance

Aluminium also has the benefit of being more resistant to fire. While the material will melt at 659°C, it offers considerably more resistance than virtually any other material covered in the post.

4. Increased Security

Finally, some homeowners choose aluminium because it improves security. As a strong material, it adds a layer of protection to prevent “smash and grab” crimes.  

5. Discreet

Aluminium frames are in fact very discreet and can be painted to match the colour of the external windows. Must be more discreet than the chunky frames of timber and PVC. 

6. Weather Resistance

Weather resistance is another benefit of this type of glazing. Units can survive decades in the sun.

Cons of Aluminium Secondary Glazing

1. Not Thermally Efficient

While aluminium secondary glazing will improve insulation in your home, it is less thermally efficient than other options. For example, the underlying material is more conductive, allowing more heat transfer than modern uPVC and timber units.

2. Affordability

Timber is the most expensive. PVC is potentially cheaper, and Aluminium is in the middle price range. However Aluminium secondary glazing frames are easy to forge.

The Pros And Cons Of Timber Secondary Glazing Frames

Wood was the original material used in secondary glazing and is still in prolific use today. That’s because timber was readily available in towns and cities in the UK.

Over time, it has become a traditional and celebrated material. Homeowners often seek it out because of its character and charm.

However, as you will read, the timber frame secondary glazing story isn’t entirely rosy. Using wood has significant drawbacks.

Pros of Timber Secondary Glazing

1. Versatility

Versatility is one of timber secondary glazing’s main perks. You can paint it any colour to complement your room or home’s design.

If you paint your frames, it is best to do it off-site first. This approach lets you paint all the crevices and angles, giving the frame a more complete look. It also stops paint from getting onto your window frames or sills.

Timber is also straightforward to shape. This latter benefit is helpful if you live in a residence with non-standard or awkwardly shaped window frames.

2. Insulation

Timber secondary glazing also provides better insulation than aluminium. That’s because wood has better thermal insulation properties – up to ten times the thermal insulation capacity of concrete and over 400 times that of solid steel.

This excellent insulation comes from timber’s internal structure. The material contains billions of tiny gaps and air pockets that prevent heat from quickly travelling from one side of the material to the other.

Timber’s insulating properties are so good that many sustainability-oriented projects use it as an integral part of building design. Wood helps to retain more heat, reducing energy bills and CO2 consumption.

3. Beauty

Finally, wood offers outstanding aesthetics that many homeowners love. The material naturally complements traditional homes and interiors, preventing secondary glazing from standing out or disrupting a room’s theme.

Wood also offers warmth. Adding it to interiors makes them feel more natural and welcoming – ideal for anyone wanting to feel more hygge.

Cons of Timber Secondary Glazing

1. Susceptible To Moisture

Timber’s main downside is its susceptibility to moisture. Wood can absorb vapour from the air, changing its shape over time.

It is possible to reduce the amount of moisture the material absorbs by installing extractor fans and interior dehumidifiers. However, these options are expensive and don’t eliminate the risk entirely.

Furthermore, even if you do achieve a low-moisture environment, wood can still warp as it ages. The internal cellular structure can change shape, causing the material to shift and move.

2. Added Maintenance

Timber secondary glazing frames also require additional maintenance. Wood requires regular painting and protection to keep it looking its best compared to modern alternative materials, usually every three to five years.

The maintenance you have to do depends on the frames’ weather exposure. Luckily, secondary glazing sits behind your primary windows, making rain less of an issue. However, UV radiation and other factors can still fatigue timber, so it is something you will need to keep an eye on.

3. Bulkier Appearance

Wooden windows also have a bulkier appearance compared to some aluminium options. That’s because wood needs to be a minimum size to provide adequate strength to house the glazing.

Bulk is a problem for two reasons: aesthetics and light penetration. When frames are thick, it can make rooms dimmer.

4. Higher Cost

Finally, wood secondary glazing frames are surprisingly expensive. The high price comes from a combination of the cost of the underlying material and the processing involved in transforming it into a frame, so that’s something you’ll want to watch out for.

The Pros And Cons Of uPVC Secondary Glazing Frames

uPVC is the newest material for secondary glazing frames. Homebuilders began introducing it to the UK in the 1980s, believing it would provide a cheap alternative to existing technologies and bring down bills.

Since then, it has come to dominate the market. Aluminium and timber secondary glazing are rare these days.

Pros of uPVC Secondary Glazing

1. More Cost Effective

uPVC secondary glazing frames are more cost-effective than their timber and aluminium counterparts. Checkatrade data reveals that the average aluminium frame is over £475, compared to just £325 for uPVC.

2. Low Maintenance

uPVC secondary glazing maintenance requirements are also substantially lower than timber. To clean them, you simply wipe them down with a damp cloth.

3. Weather Resistant

Weather resistance is another benefit of this type of glazing. Units can survive decades in the sun.

uPVC manufacturers enable this through the use of various additives. These help frames resist UV radiation and mould growth, including biocides and titanium dioxide.

As such, most uPVC frames last over 20 years. Some can last as much as 35 years in areas exposed to less sun.

4. Lightweight

Finally, uPVC windows are exceptionally lightweight. This probably makes them more straightforward to handle and install, potentially reducing labour costs compared to timber windows.

Cons of uPVC Secondary Glazing

1. Aesthetics

Unfortunately, most homeowners think uPVC is less aesthetically pleasing than conventional timber or aluminium frames. Thick plastic frames aren’t most people’s idea of luxury.

However, while this was certainly true in the past, it is less of a concern today. Manufacturers have improved their production processes in recent years, making modern designs significantly better. Many uPVC options now look similar to classic wood, enhancing their appeal considerably.

2. Recyclability

Lack of recyclability was another issue that plagued uPVC windows historically. However, new recycling options are becoming available all the time that facilitate the reuse of the material.

3. Frame Colour Changes

After a while, the uPVC frames do change into a yellow colour which could be an undesired appearance for man.

Get Secondary Glazing London

If you want to learn more about Aluminium secondary glazing in London or get a free quote, call our team.