What does composite mean? 

A composite material is composed from at least two or more constituent materials. The individual materials used to form the composite generally have very different chemical and / or physical properties and remain identifiable within the composite. The combination of the component parts results in a material that has unique properties and is superior to the individual elements. 

What are composite windows?

Composite windows are manufactured by combining two different materials, which together provide hybrid properties. There are currently two main types of composite window on the market - one comprises an aluminium-clad timber frame and the other an aluminium-clad UPVC frame. 

Aluminium-clad timber frame windows are produced largely of timber, while aluminium-clad UPVC windows are mostly made of UPVC. Both frame types are similarly overlaid externally with a powder-coated aluminium profile. This creates a more durable and longer-lasting product, which requires almost no maintenance. Aluminium-clad windows provide a stylish, sleek alternative to traditional timber or UPVC products. They also provide the opportunity to have a dual colour finish, so you enjoy greater design freedom inside and out.

Aluminium-clad timber or aluminium-clad UPVC? 

We are committed to delivering high performing, energy efficient windows and doors, which are both aesthetically pleasing and durable. As such, our composite windows have aluminium-clad timber frames, not UPVC. Why? We use timber for its substantial advantages over UPVC. Some of these include:

Aesthetics and Design 

Our timber frames make a stylish statement and come in a range of different profiles. They are custom-manufactured, unlike generally mass-produced UPVC frames. Engineered timber tends to be stronger than UPVC, enables more weight bearing and so facilitates production of larger, more impressive units than could otherwise be manufactured from UPVC. 

Sustainability and Performance 

Wood has low thermal conductivity, making the timber frame of our alu-clad windows an excellent insulator. Our best-performing alu-clad products deliver better insulation and U-values than UPVC windows. It is also more environmentally friendly to work with timber than UPVC. 


In the short-term, alu-clad timber windows are usually a more expensive option than alu-clad UPVC windows. However, when the lifecycle and thermal performance of each frame type are analysed, we start to see how the long-term cost benefits of timber - reduced heating bills, long lifespan - outweigh the initial savings of uPVC. It’s also important to consider the potential value increase to a property for each frame type. Installing timber frame windows in your house increases its potential value over and above uPVC installation.  

Why choose Norrsken's composite windows? 

When compared to all-aluminium, all-timber and uPVC products, composite windows provide numerous benefits. Our stylish timber frames are simply more thermally efficient than all-aluminium or uPVC products. The streamlined powder-coated exterior of our composite windows has near-zero maintenance requirements – whereas all-timber windows tend to need involved maintenance to last, and even UPVC windows require more upkeep than alu-clad models. The lifespan of composite models usually exceeds that expected for competition products and, in terms of production, thermal performance and disposal, they are more sustainable and - environmentally – the obvious fenestration solution. 

The blend of materials used to manufacture our composite windows work in combination to deliver exclusive hybrid properties superior to all-aluminium, all-timber, all-UPVC and UPVC-alu-clad products.

Frequently Asked Questions

What are composite windows ?

Composite windows are manufactured by combining two different materials, which together provide hybrid properties. There are currently two main types on the market - aluminium-clad timber windows and aluminium-clad UPVC windows.

Aluminium-clad timber or aluminium-clad upvc ?

We recommend timber composite windows for their many advantages over UPVC, including the durability and strength of engineered timber, better insulation and U-values than UPVC windows, a longer lifespan and the potential value increase to a property.

Are composite windows better than upvc ?

Composite windows provide numerous benefits compared to uPVC products. Timber frames are more thermally efficient than uPVC, while the streamlined powder-coated exterior has near-zero maintenance requirements. The lifespan of composite models usually exceeds that of uPVC windows and in production, thermal performance and disposal, they are less environmentally impactful.

Are composite windows worth it ?

Composite windows tend to be more expensive than uPVC models, but offer a wider range of benefits including better thermal performance, aesthetic appeal, a longer lifespan, use of more environmentally friendly materials and lower maintenance. They are certainly the smarter choice for a well-insulated home in the long run.

Can composite windows be painted ?

Our aluminium-clad timber composite windows can be finished in any RAL colour with a powder-coated finish. Dual colour finish - different colours inside and out - is available as standard, so there is no shortage of options when choosing the colour of your windows! Internally the windows can be repainted later if desired.

How long do composite windows last ?

With proper maintenance, composite windows can last upwards of 50 years - a considerable uplift from the 20-odd year lifespan of uPVC windows.

Who sells composite windows ?

At Norrsken, we supply and install beautiful, durable and energy-efficient composite windows and doors in many types of domestic and commercial projects. With U-values as low as 0.64, several of our models are suitable for use in Passive House, retrofit and low-energy projects.

choosing your colour scheme

What's trending? What do you need to consider?