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Bay window guide

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Bay windows are seen in all types of houses – from Tudor and Georgian period homes to modern new builds – thanks to their increased internal floorspace, plentiful natural light and architectural interest. 

This type of window looks fantastic when installed correctly, but the devil is in the details. The wrong choices in shape, form or material could impact the appearance of a home dramatically. So, our experts have created this guide to help you consider every aspect from start to finish.

What is a bay window?

A bay window projects outwardly from the main walls of a property, creating an alcove within the room from which it projects. Bay windows offer a distinct architectural feature to a property, adding character to both the interior and exterior. The most common style for a bay window is a larger sash in the centre with two smaller sashes on either side, though the configuration can vary with different architectural design options, such as bow windows and box bay windows. Bay windows offer more space inside the home and improve the amount of light and ventilation entering a room.

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What are the styles of bay windows?

Bay windows can be created in many custom-made styles to suit the architectural requirements of the homeowner, with plenty of size, angle and window quantity configurations being possible in a wide range of materials and glazing types.

The most popular styles are listed below:

  • Traditional canted bay window
  • Box bay window
  • Bow bay window
  • Corner bay window
  • Oriel bay window

Each of the above bay window styles have distinctive designs. 

Traditional canted bay window

Canted bay windows are the most common style of bay window. (Adobe)

The traditional bay window, also known as a canted bay window, is a style that is commonly seen in homes built in Victorian and Edwardian architectural styles. This design has a large central fixed window with two smaller windows positioned at a 30- or 45-degree angle on either side, creating a projection beyond the front of the property.

Box bay window

A more modern aesthetic is achieved with a box bay window. Rather than the two angled side panels of a traditional bay window, a box bay window has a wider central window, and the two smaller windows at each side are set at 90 degrees, creating a rectangular shape.

Bow bay window

This bow oriel window features two openable casement windows and three central fixed sashed. (Adobe)

A bow window typically has four or more sashes rather than the three typically used in a traditional or box bay window. These windows are joined together at smaller angles, allowing for a more curved or bow-like appearance.

Corner bay window

A corner bay window is positioned at the corner of a building and is typically configured as a larger central window flanked by two smaller side windows fixed at 90-degree angles. Corner bay windows offer views from the property and allow extra natural light to enter the room.

Oriel bay window

While most bay window styles will see the window affixed to brickwork from the ground that follows the angles of the window, oriel bay windows are supported by cantilever brackets or structures, meaning that only the window protrudes from the property and the design does not reach the ground.

Double storey bay window

Double storey bow bay windows on post-war home. (Adobe)

In Tudor, Georgian, or sometimes Victorian homes, bay windows can be continued up to the first floor. This creates a sense of drama to the architecture, and provides extra space in rooms upstairs, such as bedrooms or bathrooms. 

Bay window opening styles

The decision on the opening style will be informed by the house’s era of design and build. Generally (although there are exceptions to every rule), Tudor design used casement windows with leaded glazing, Georgian bays are seen with sliding sash windows and more-modern homes use a fixed central sash with opening windows on the side panels. 

Bay window materials

When choosing the best materials for a bay window, it is important to consider several factors, such as durability, budget, maintenance and preferred aesthetics. Here, we provide information about the most widely used window frame options for bay windows and look at the benefits of each.

Some popular materials for a bay window include:

  • Unplasticised polyvinyl chloride (uPVC)
  • Wood
  • Aluminium
  • Composites

uPVC window frames are made from a form of durable plastic. They are typically the most cost-effective option when installing bay windows and come with a range of colours, opening and hardware options. uPVC windows are renowned for being durable and long lasting while requiring little maintenance. 

Wooden window frames can offer a more charming aesthetic to any home, enhancing the character and appearance of both traditional and modern properties. Wooden frames offer a great deal of versatility when it comes to design, allowing for style and design preferences that complement the home.

Aluminium windows are a popular choice for many homeowners, offering architectural style, slim profiles and the ability to powder coat in any colour. Aluminium framed windows are incredibly low maintenance, durable and resistant to rust and rot. They usually come with a higher up-front cost.

Composite framed windows are made to look like wooden window frames but are a combination of wood, vinyl and fibreglass. This combination of materials allows for the appearance of wood while being more durable and requiring less maintenance than actual wooden window frames. 

When considering materials for a bay window, maintenance, aesthetics, budget and design will all be important factors. The best material will ultimately come down to the individual homeowners preference for the unique benefits and design features of each.

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Bay window glass options

There are several glass options that can be used in a bay window. The most popular glass options are listed below:

  • Double-glazed glass
  • Triple-glazed glass
  • Decorative glass
  • Frosted glass
  • Tinted glass
  • Low-emission glass

Double-glazed windows are typically the most popular choice for modern bay windows, to meet current building regulations. Double glazing reduces exterior noise and heat transfer, keeping the indoor temperature comfortable. Plus, it is more energy efficient than single-glazed glass. Double-glazed glass is manufactured with two panes of glass separated by an air-sealed space.

Triple-glazing is manufactured in the same way as double-glazing but has an extra pane of glass and an extra air-sealed space between the second and third panes. Triple glazing offers greater energy efficiency and allows for even less exterior noise to enter the home than double glazing. However, triple glazing can increase the costs, due to the higher quality and increased manufacturing involvement.

Decorative glass for bay windows can be configured to meet practically any design requirements to add a desired aesthetic to the home. Popular styles of decorative glass include leaded, stained or patterned glass.

Frosted glass is typically used in windows in rooms that require privacy, such as bathrooms or downstairs spaces in homes on busy roads. Frosted glass obscures the view through the window while allowing natural light to enter the room.

Tinted glass reduces the amount of light and heat being transmitted via a window. It is popular for windows exposed to a high amount of glare from the sun. Tinted windows will help to reduce the strength of the UV rays entering a room.

Low-emission glass (also known as Low-e) is very energy efficient, reducing the amount of heat radiating from a window during the colder months. This is achieved with a thin film layer on the glass that reflects heat back inside the property rather than allowing it to escape via the glass. While Low-e glass reduces the strength of the UV rays entering a property, it also impacts the amount of natural light coming through the window.

The type of glass selected for a bay window will depend on the specific requirements of the homeowner and any desired features relating to privacy, design, energy efficiency, noise reduction and UV ray reduction.

How much do bay windows cost?

The number of window panes required, the size and style of the window, specifications, the materials used for the frame, the glazing options and any design or hardware additions will all affect bay window prices. The cost of a bay window can also vary by property type, the supplier used and the regional location of the property.

The average cost for a traditional bay window can vary greatly based on the materials used. For example, the average cost of a uPVC bay window is between £1,250 and £1,950, while the average cost of a wooden-framed bay window is between £2,750 and £3,300. The same variations apply when looking at costs depending on the type of glass used. The average cost of a uPVC double-glazed bay window is between £1,250 and £1,650, while the average cost of a triple-glazed bay window is significantly more expensive, costing between £2,000 and £2,300.

The property type will impact the cost of adding bay windows, due to the number of windows required. A flat typically has one bay window, while a terraced or semi-detached property typically has two bay windows. A detached property normally has between two and four bay windows, and sometimes even more depending on the property style. It will be important to bear in mind that if you’re renovating the windows of a period property that the moulding styles should always be replicated, in order to retain the heritage style and charm. This could also come at an increased price, but neglecting these design details will be reflected in house value. 

It is important to consider that the addition of extra security features or upgraded hardware will typically add to the costs involved. The costs of any remedial work to the dwarf brickwork below the window might also require close attention.

Keep in mind that the cost of bay windows will vary based on the manufacturer and supplier used, so it is advisable to request quotes from several suppliers to get an average price for bay windows. It is a good idea to request quotes from reputable companies that offer the expected assurances and guarantees for the installation of bay windows.

Timber bay windows provide a sense of character that uPVC and aluminium can’t replicate, but they might not suit every budget. (Adobe)

Bay windows pros and cons

When considering bay windows, it is important to consider both their advantages and disadvantages.

Some advantages of bay windows include:

  • More natural light and space in a room. Because bay windows protrude from a room, there is a distinct advantage in that additional internal space is gained, and the larger window area adds to the amount of natural light coming in, making for a bigger and brighter room.
  • Better views and increased ventilation. The larger window area and shape of a bay window offer panoramic views of the space outside. What’s more, the higher number of openings in a bay window improves ventilation when compared with a standard sash window.
  • Increased character and aesthetic appeal. Bay windows are typically seen in Edwardian and Victorian style properties and are considered to add character to a property, while box bay windows add a more modern aesthetic to a home.

Some disadvantages of bay windows include:

  • Higher costs. The cost of bay windows is typically significantly higher than the cost of flat windows, due to the more skilled approach required in the installation of bay windows and the additional window materials used.
  • Lower energy efficiency. As bay windows protrude from a property and have a larger glass area than flat windows, they are typically less energy efficient. Upgraded glazing options can improve energy efficiency, but these come with a higher up-front cost, so energy cost savings in the long term should be considered.
  • Less privacy. When a bay window is positioned at the front of a property that is exposed to the road, privacy can be compromised, though this can be remedied with the addition of blinds, shutters, curtains or obscured glass.
  • Higher maintenance. Because bay windows protrude from the exterior of a property, they are more exposed to the elements, resulting in more maintenance being required.

It is advisable to consider all the pros and cons of bay windows, in addition to your own individual requirements, when deciding on adding or replacing bay windows.

What to look for in a bay window quote

When getting a quote for bay windows, it is important to look at the design specifications, the cost of installation, the reputability of the window fitter and guarantees offered by the supplier or fitter. Also, research in advance if you qualify for any windows grants to ease the cost of installation.

When looking at the costs for bay windows, it is important to consider the number of bay windows required, the bay window style, the frame material and any additional features you may wish to add, such as upgraded glazing, design or security features. The number of bay windows required and their sizes can cause the overall cost of bay windows to vary. On average, a double-glazed bay window will cost between £1,250 and £3,300. 

While cost is an important factor when choosing a supplier for bay windows, it is essential to keep in mind that specialist installation skills are required for fitting a bay window and reputable companies will ensure that your new windows are of good quality and installed properly.

It is advisable to understand what manufacturer and fitting guarantees are offered by the window fitters you obtain quotes from. Guarantees can help if the window standard or fitting quality falls short of expectations and can maximise the lifespan of your new windows. 

When considering new bay windows for your home, it is a good idea to obtain multiple quotes from local window installers to find the best value and to get a more accurate idea of the cost of bay windows that meet your specifications. 

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Frequently asked questions

Bay windows are typically more expensive than standard window designs. The additional costs involved are due to a few factors, including installation requirements, materials used, design requirements, custom requirements and glazing options.

Bay windows are normally more complex to install than casement or tilt and turn windows. This complexity requires more time and skill from the bay window installer, which will typically incur higher installation charges.

As mentioned earlier, there are several styles of bay windows, ranging from the simpler traditional canted and box bay window styles to the more intricate bow and custom bay window configurations. Typically, the more complex the style of bay window required, the higher the cost will be.

While the cost of bay windows is generally higher, they do offer benefits that cannot be achieved with standard windows, including panoramic views, more natural light, increased indoor space and greater aesthetic and architectural appeal.

There are a few variables to consider when looking at bay uPVC window prices, including the size of the window, the number of windows in the bay window configuration, the glazing options, the supplier and installer and any other design, security or hardware specifications.

The approximate cost of a uPVC bay window is between £1,500 and £4,000, though installation requirements and the complexity of the bay window style could alter this estimate. 

Painting existing window frames has grown in popularity in recent years, with new technologies meaning that most bay window frame materials can be painted.

Painting wooden bay window frames is easily achieved by sanding and preparing the window frame and then painting it with exterior grade wood paint.

uPVC, aluminium and composite bay window frames can be painted with specialist paints as a DIY project or by hiring a professional window frame spraying or wrapping company.

It is always recommended that the appropriate paint is used when painting a wooden, aluminium, uPVC or composite window frame. Painting window frames can impact the window warranty, so it is important to check this prior to painting a bay window frame.

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Liz is a distinguished author and a leading voice in the realm of home improvements. With an unwavering dedication to sustainable living, she brings a wealth of expertise as a home improvements connoisseur, specialising in energy-efficient enhancements.

With a particular emphasis on reducing energy consumption, Liz’s passion shines through in her advocacy for upgrades like double glazing windows. 

Through her insightful writing, Liz empowers homeowners to embrace greener lifestyles without compromising on comfort or style. Her articles, guides, and expert opinions provide practical, step-by-step advice for those eager to make a positive environmental impact. Whether you’re a DIY enthusiast or a homeowner seeking to curate a more sustainable space, Liz offers a wealth of knowledge to inspire and guide your home improvement journey.


Amy Reeves


Amy is a seasoned writer and editor with a special interest in home design, sustainable technology and green building methods.

She has interviewed hundreds of self-builders, extenders and renovators about their journeys towards individual, well-considered homes, as well as architects and industry experts during her five years working as Assistant Editor at Homebuilding & Renovating, part of Future plc.