What is a composite window and what are their pros and cons?

contemporary house with composite windows
(Image credit: Velfac)

Just what is a composite window? You may well have heard of them, but do you know how they are made, what they cost or what they look like? If not, we are here to explain all.

With so many different windows styles available, choosing the right products for you and your home can be extremely tricky. You need to make sure that the windows you opt for not only look great but that they will also fit in with your budget and maintenance requirements. 

Here, we take a look at one of the main options out there — composite windows. We have spoken to the experts to find out exactly what they are and what they could offer you.

What is a composite window?

For many people looking to install new windows into their home, the choice tends to come down to aluminium windows, timber or composite. 

"Composite windows are windows with frames made of two different materials," explains Rebecca Clayton, communications director at IQ Glass. "These are most often timber on the inside of the window and aluminium on the outside."

"Increasingly used across the UK, composite frames combine external aluminium with inner timber to give the best of both worlds — an attractive timber internal frame protected by durable, low maintenance, sleek aluminium," says Ollie Chisman, sales director for domestic projects at Velfac.

Composite windows come in all shapes, sizes and colours so there is something to suit pretty much every style of house — that said, they are most commonly seen on modern and contemporary styles of property, where their unfussy external appearance looks particularly fitting.

cross section of a composite window

True composite windows, such as those from VELFAC, feature a high quality timber frame internally and a slim aluminium sash profile externally, along with double or triple glazing.  (Image credit: Velfac)

Are there different types of composite window?

Yes, not all composite windows are created equal. Some are simply clad in aluminium on one side rather than being solid aluminium. 

"Not all composite windows are the same, even if they all display wood and aluminium," explains Chiara Marfella on behalf of VELFAC. "VELFAC is one of the few 'true composites' compared to 'alu clad' windows. 

"Here is the difference between the two. With the sash and mainframe produced primarily from timber and only faced with aluminium, an aluminium clad window is essentially a timber window, where the external frame is covered with a layer of aluminium for protection. 

"True composite window systems, on the other hand, feature an independent aluminium sash on one side and timber mainframe on the other. In this case, the individual materials are easily distinguishable within the true composite structure and are bonded together to provide unique properties and excellent performance."

What are the advantages of composite windows?

Composite windows offer many benefits when compared to timber windows as well as other types of window — they are very thermally efficient, attractive and low maintenance, to name but a few of their advantages. 

"The advantages of composite windows is that they tend to offer a very high level of insulation due to the natural insulation characteristics of timber," says Rebecca Clayton. "The aluminium on the outside is then low maintenance which removes one of the downsides of using timber which requires ongoing maintenance through its life. It is easier to achieve high levels of insulation and they outperform plastic window frames." 

"Composite windows bring great design flexibility — the opportunity to create large windows, for example, and to specify different frame finishes inside and out," adds Ollie Chisman. "The composite design allows the construction of distinctive slim frames which maximise natural light while delivering excellent insulation, acoustic control and enhanced security."

To add to their many benefits, composite windows also have exceptional longevity.

"A composite window can offer an operational lifetime of up to 40 years, and both aluminium and timber are also recyclable, improving sustainability," says Ollie. "Composite windows are not the most expensive on the market, and when energy savings are taken into account, together with minimal maintenance costs, a composite system can prove to be the most cost-effective option for many projects."

composite windows

Composite windows such as these from VELFAC offer the best of both worlds — timber internally and sleek aluminium externally.  (Image credit: VELFAC)

What are the disadvantages of composite windows?

As with all things, there are one or two cons to composite windows when compared with some other types. The two main disadvantages that affect most people's choice is down to window sizes and cost. 

"The downside of composite systems when compared to aluminium is that the frame is thicker than a thermally broken metal frame and the frame size is similar to a plastic window," says Rebecca Clayton. "With aluminium you can achieve 20mm sightlines with floor to ceiling glass. This isn’t possible with composite systems. The size of window is also reduced when compared to aluminium framed systems." 

How much do composite windows cost?

Obviously the amount you pay for windows will depend on their size and how many you are ordering.

Composite windows are certainly not the cheapest option around — for that you will need to look at uPVC and softwood frames. At the upper end of the price scale lie aluminium, composite and hardwood.

Work on the assumption that composite windows will cost you between £10,000 and £25,000 — and expect to pay 25% more for triple glazing.

Natasha Brinsmead

Natasha is Homebuilding & Renovating’s Associate Content Editor and has been a member of the team for over two decades. An experienced journalist and renovation expert, she has written for a number of homes titles. Over the years Natasha has renovated and carried out a side extension to a Victorian terrace. She is currently living in the rural Edwardian cottage she renovated and extended on a largely DIY basis, living on site for the duration of the project. She is now looking for her next project — something which is proving far harder than she thought it would be.