Composite windows are an increasingly popular choice for homeowners seeking a balance of durability, energy efficiency and style. 

Modern composite windows combine the best qualities of materials such as wood, uPVC and aluminium, resulting in a durable product that can outperform traditional window options.

Although composite double glazing windows may have a higher initial cost than standard uPVC windows, they offer long-term value. The extended lifespan, exceptional performance and low maintenance requirements of composite windows make them a smart investment for many homes.

This guide explores composite windows, providing valuable insights into their unique features, benefits and cost considerations.

What is a composite window?

A composite window is made from a combination of materials – usually wood or uPVC and aluminium. The manufacturing process involves creating a strong, insulating core, often from timber or uPVC, and then cladding the exterior with a low-maintenance material, such as aluminium. 

This combination of materials offers wood’s natural beauty, uPVC’s insulating properties and aluminium’s weatherproof durability. Composite windows are engineered to provide the best features of each material while minimising their drawbacks.

Pros and cons of composite windows

Like all windows, composite windows have pros and cons. While they’re strong, durable and attractive, there are still considerations to weigh against other window materials such as timber, uPVC and aluminium. 

Pros of composite windows

  • Excellent durability and weather resistance: composite windows are engineered to withstand the elements, offering superior durability compared to traditional window materials. Combining robust inner cores and weatherproof outer layers creates a window that can resist rain, wind, snow and sun damage. This weatherproof design helps prevent issues such as warping, cracking or fading over time, ensuring your windows maintain their appearance and performance for decades.
  • High energy efficiency: composite windows offer excellent thermal insulation properties thanks to their multi-layered construction and advanced glazing options. The insulating core materials help prevent heat transfer, while the tight-fitting frames minimise drafts. Many composite windows also feature double or triple glazing, enhancing energy efficiency.
  • Low maintenance requirements: one of the key benefits of composite windows is their low maintenance needs. Unlike traditional wooden windows, which require regular painting and treatment, composite windows are designed to maintain their appearance with minimal upkeep. The outer layer is highly weather resistant and doesn’t typically require repainting. Simply wiping the frames occasionally with a damp cloth is usually sufficient to keep them looking clean and fresh.
  • Attractive, versatile aesthetics: composite windows offer a range of attractive design options to suit any home style, from traditional to contemporary. Many composite frames feature a wood-effect finish that mimics the natural beauty of timber without the associated maintenance requirements.

Cons of composite windows

  • Higher cost compared to standard uPVC windows: one of the main drawbacks of composite windows is their higher price point compared to more basic window options, such as uPVC. 
  • Heavier than uPVC windows: composite windows are typically heavier than their uPVC counterparts due to the dense inner core materials and sturdy outer layers. This additional weight can sometimes complicate installation, particularly in older homes with weaker wall structures. In some cases, extra reinforcement may be necessary to support the weight of the windows, which can add to the overall installation time and cost.
  • Limited colour options compared to painted wood windows: while composite windows offer a good range of colour options, they may not provide the same level of customisation as traditional painted wood windows. With wooden frames, homeowners can choose virtually any paint colour to match their design preferences. Composite windows, on the other hand, are typically limited to a set range of factory-applied finishes (but can sometimes be custom-made or painted in other colours).

Materials for composite frames

Several different materials are available for composite window frames, each with unique characteristics and benefits. The most common types are timber-aluminium, uPVC-aluminium and fibreglass composites.

Let’s explore these in greater detail:

Timber-aluminium (Aluclad)

Timber-aluminium windows, also called Aluclad windows, feature a timber core with aluminium on the exterior. 

Homeowners often choose Aluclad windows for their natural wood interior, low-maintenance exterior and excellent weatherproofing. 

The timber core provides good insulation, while the aluminium cladding protects against the elements. Aluclad windows are a great choice for period properties or homes with a traditional aesthetic.


uPVC-aluminium composite windows have a uPVC core with an aluminium exterior. These windows are chosen for their superior insulation, affordability and modern look. 

The uPVC core offers excellent thermal performance, and the aluminium cladding lends a contemporary appearance and weatherproof durability. 


Fibreglass composite windows are made from fibreglass, a strong, lightweight and highly insulating material. Fibreglass windows are extremely durable, with a lifespan of 50+ years, and they require minimal maintenance. 

They offer excellent energy efficiency and can mimic the look of painted wood. However, fibreglass windows tend to be the most expensive composite option.

What styles do composite windows come in?

Composite windows are incredibly versatile and can be manufactured in a wide range of styles to suit various architectural designs and preferences. 

Popular composite window styles

  • Casement windows: hinged on one side and opening outwards, casement windows are a classic and versatile option that suits many home styles. They provide excellent ventilation and can be mounted in pairs or with fixed panes for larger openings
  • Sash windows: featuring two sliding panels, sash windows are a traditional style particularly popular in period properties. Composite sash windows can replicate the authentic appearance of timber while offering modern performance benefits
  • Tilt and turn windows: with innovative hinges that allow the window to tilt inwards at the top or open fully from the side, tilt and turn windows provide flexible ventilation options and easy cleaning. They’re a popular choice for modern homes and apartments
  • Bay and bow windows: extending outwards from the main walls of the house, bay and bow windows create a striking architectural feature and can flood your interior with natural light. Bay windows typically have three openings, while bow windows are curved and have four or more
  • Picture windows: designed to maximise views and natural light, picture windows are large, fixed panes that don’t open. They’re often combined with other window styles, such as casements, to provide ventilation where needed
  • Bifold windows: with multiple panels that fold back on themselves, bifold windows can create an unobstructed opening that blurs the line between indoors and outdoors. They’re perfect for homes with beautiful views or gardens

In addition to these popular styles, composite windows can also be custom designed to suit your specific requirements. 

Many window companies offer bespoke design services, allowing you to create unique shapes, sizes and configurations to complement your home’s architecture.

How much do composite windows cost?

The cost of windows with composite frames varies depending on the type of composite, size, style and glazing. 

On average, expect to pay around £500 to £1,200 per window, including installation. Timber-aluminium windows start at about £500 each, while higher-end fibreglass windows can cost £1,000 or more per window.

Window typeMaterialSize (mm)Average cost (per window, excluding installation)
CasementuPVC-aluminium600 x 900£400-£600
Timber-aluminium600 x 900£600-£900
Fibreglass600 x 900£800-£1,100
SashuPVC-aluminium900 x 1200£700-£1,000
Timber-aluminium900 x 1200£1,000-£1,400
Fibreglass900 x 1200£1,300-£1,700
Tilt and turnuPVC-aluminium900 x 1200£500-£700
Timber-aluminium900 x 1200£700-£1,000
Fibreglass900 x 1200£900-£1,200
Bay (three-pane)uPVC-aluminium2000 x 1200£1,000-£1,600
Timber-aluminium2000 x 1200£1,600-£2,400
Fibreglass2000 x 1200£2,300-£3,100

These are rough estimates; actual prices may vary based on your specific requirements and location.

Additional factors that impact costs of composite windows

  • Size: larger windows, such as those for picture windows or patio doors, will generally cost more than smaller ones due to the increased materials and labour required
  • Style: complex window styles, including bay or bow windows, often have a higher price point than simpler styles such as casement windows. This is because they have more detailed manufacturing and installation processes
  • Glazing: upgrading to advanced glazing packages, such as triple glazing or laminated glass, can add to the overall cost of your composite windows. However, these upgrades can also improve energy efficiency, noise reduction and security
  • Customisation: bespoke colour options, decorative glazing or unique hardware finishes may incur additional costs compared to standard composite window configurations
  • Installation complexity: window installations that require structural alterations, such as lintel replacements or wall reinforcements, can increase the overall project cost

It’s best to consult with several local window suppliers and installers to get an accurate quote for your specific composite window requirements. They can assess your needs and provide tailored pricing based on your home’s unique specifications.

How long do composite windows last?

Composite windows can last 30-50 years or more with proper care and maintenance. 

To keep your windows in top condition, clean them regularly with soap and water, and inspect the frames annually for signs of damage or wear. 

Every 5-10 years, the window frames may need repainting or resealing to maintain their appearance and weatherproofing. The exact maintenance requirements will depend on the specific composite material. 

Expect to pay around £100-£300 per window for professional repainting or resealing.

Are composite windows worth it?

Composite windows offer a versatile, high-performance solution for homeowners seeking an attractive, energy-efficient and low-maintenance window option. 

Combining the best properties of materials such as uPVC, aluminium, timber and fibreglass, composite windows provide superb durability, weatherproofing and insulation.

While the initial cost of composite windows may be higher than standard uPVC or timber options, their long lifespan, minimal upkeep requirements and potential energy savings can make them a wise long-term investment. 

With a wide range of styles and customisation options, composite windows can seamlessly integrate with traditional and modern home aesthetics.

To ensure the best performance and value for your investment, work with reputable window manufacturers and experienced installers who can guide you through the selection process and provide expert installation.

Composite windows FAQs