Oriel windows, also called frameless box windows, are a current architectural trend among homeowners and architects.
Their modern features, which seamlessly blend functionality with striking aesthetics, fill a room with more light than a traditional window, adding a contemporary touch to any space. Oriel windows have the added benefits of providing innovative design solutions, such as a seating area and giving the room a more spacious feel.
- Residential homes: Oriel windows add light and a sense of space in kitchens, living rooms, or bedrooms.
- New extensions: Oriel window’s creative design possibilities add a bold modern statement to a new extension of an existing home.
- Commercial projects: Oriel windows add a statement of clever design to office buildings, retail spaces, and public structures by providing more light and seating areas.
Below, Door and Window Experts explores their key features, uses, and benefits.
What are Oriel windows?
Oriel windows are characterised by their three-dimensional, glass-box appearance. These windows project outward from the face of a building, creating a unique “pop-out” effect.
Oriel windows are not new; they have been around for centuries, with intricate designs in stone and wood featured in castles and churches and in the home.
Now manufactured in modern materials, all glass or a combination of glass and aluminium is the most popular choice to provide a modern, clean, slimline box aesthetic, making the box window a new popular term for this style.
Image Courtesy of John Knight Glass, Oriel Windows Experts in Liverpool, Cheshire and the North West.
What are frameless box windows?
Frameless box windows, a subset of oriel windows, take this design further by eliminating visible frames and using structural glass for seamless transparency.
The combination of structural glazing and silicone bonding allows for an uninterrupted flow of glass, making frameless box windows a modern design statement. These windows can serve as light-filled architectural features or functional spaces such as window seats.
Frameless box windows that can flood interiors with natural light are popular with architects, designers, and homeowners looking for clean, minimalist lines.
Image Courtesy of HBD Systems, Oriel Windows Experts for Hertfordshire, London and Home Counties.
What is the difference between an oriel window and a bay window?
Both protrude from the façade. However, the difference between an oriel window and a bay window is that the bay window reaches the ground, whereas an oriel window is canter-levered and does not reach the ground.
The benefits of oriel windows and frameless box windows
The unique architectural interest of the oriel and frameless box windows is their standout feature. They add depth and dimension to a building facade, creating a visually striking and intriguing feature that captivates the eye.
The cantilevered designs of oriel windows create a dramatic effect, making the glass box appear to float from the building’s façade. Extending outward and bringing in more light, oriel windows make rooms feel larger and more open.
The large, glazed surfaces maximise and enhance natural light, making interiors feel brighter and more spacious, particularly beneficial for dark areas or north-facing rooms to provide a sense of well-being.
With double or triple-glazing options, oriel windows enhance thermal performance, keeping interiors warm in winter and cool in summer. Solar coatings and insulated glass options help improve energy efficiency and reduce energy costs while maintaining indoor comfort. Whilst laminated or toughened glass ensures the windows are secure and long-lasting.
Image Courtesy of IQ Glass, nationwide experts in structural glazing, technical glass structures, and oriel windows.
Oriel windows and frameless box windows as a window seat
One of the standout features of Oriel windows is the opportunity to create a built-in window seat. The deeper sill provided by these designs offers a comfortable and visually appealing space for relaxation. Window seats are perfect for reading, enjoying a garden view, adding a cosy nook in your home or as additional space-saving seating for a dining table.
Image Courtesy of IQ Glass, nationwide experts in structural glazing, technical glass structures, and oriel windows.
Key features, design and technical considerations of Oriel windows and frameless box windows
Box frameless and oriel windows are suitable for new builds, extensions, and renovations, offering a unique way to modernise residential and commercial properties.
Box frameless and oriel windows are entirely bespoke and customisable. Sizes, shapes, and configurations are tailored to the specific needs of each project, allowing for creative freedom. Options include triangle, box and angled installations, floating glass boxes, and configurations with solid bases or painted spandrel panels.
Advanced glazing techniques, such as strengthening interlayers, allow box frameless and oriel windows to support themselves without additional steel reinforcements. The load-bearing capability of the glass ensures a robust design.
Frameless box windows use structural silicone to bond glass panels at the corners, eliminating the need for traditional frames, creating a seamless, uninterrupted view and enhancing the minimalist aesthetic. Opening window panels can be incorporated for ventilation, although this may require discreet framing or additional structural supports.
The glass finish can be customised with painted borders, tinted or frosted glass, and solar control coatings; for those seeking a more prominent design, a solid base or additional framing can be included.
Oriel windows can be fitted with high-performance double or triple glazing to meet project-specific thermal and acoustic performance requirements. Thermal insulation and solar control coatings can all be integrated to enhance comfort and energy efficiency. Acoustic glass can also be specified for noise reduction in urban environments.
Do Oriel windows require planning permission?
In most cases, window replacements don’t need planning permission if they replicate the size and style of the original design. However, new oriel windows, particularly those replacing flat window designs or protruding from the building’s façade constitute as a bay window and may require planning approval.
- Replacing an existing bay window: No planning permission is needed.
- Installing new bay windows at the front: Planning permission is typically required.
- Adding bay windows at the side or rear: Usually, planning permission isn’t necessary unless the property is listed or in a conservation area.
For upper-floor installations, specific regulations apply: side-facing windows must be obscure-glazed and either non-opening or set above 1.7 metres from floor level.
Oriel windows in conservation areas
Installing oriel windows in conservation areas can be more complex due to stricter planning controls aimed at preserving the area’s historical or architectural character. Article 4 restrictions often apply and vary between locations. It’s advisable to consult the local planning authority to confirm your project meets the necessary requirements.
Checking with local Building Control is always recommended.
Installation of oriel windows and frameless box windows
The structural glazing techniques of oriel and frameless box windows require specialist manufacturers and installers.
Any mistake in the installation of structural glass will result in water ingress. Therefore, the installation staff must be experienced with structural glazed products, such as box windows. There is no margin for error; glass panels must be manufactured and installed to the millimetre.
Oriel windows are installed by bonding the glass at the corners to create an almost seamless join.
Frameless box windows rely on advanced glazing systems like Invisio to create a seamless connection between glass panels, ensuring durability and aesthetic appeal with frameless transparency.
The fixing points between the window and the building are carefully concealed to maintain a clean finish. These can often be hidden beneath interior and exterior finishes for a seamless look.
Oriel and frameless box windows must be installed to comply with Part L Building Regulations to ensure compliance with standards for thermal efficiency (U-values), glazing strength, and structural integrity.
Your installation must comply with current Building Regulations to ensure compliance with standards for thermal efficiency (U-values), glazing strength, and structural integrity.
What materials are typically used to construct oriel windows and frameless box windows?
Typically, use only structural glass and, depending on how they sit and are supported, a cantilevered base or an aluminium support frame.
How do Oriel windows compare in cost to traditional windows?
Oriel windows are more expensive than conventional bay windows because no standard-size window exists. Every element of Oriel windows is bespoke and made to the precise sizes and designs required by the installation.
Additionally, the structural silicone used, the specialist sealing and the advanced glass types make this a high-end option for any property project, but one that adds a distinctive look to a home and has masses of user appeal. You can expect to pay upwards of £5000 for a standard-sized oriel window. Most important is the expertise of the company in creating your new windows. Always ensure they have experience, and always get a full explanation of the process. If you are unsure, contact us for details of specialist suppliers and installers.
We do not recommend buying these windows on a supply-only basis for your builder or anyone not trained in these windows to fit.
Examples of Oriel Windows
The gallery below shows Oriel windows manufactured by Glideline Ltd shwoing both large windows, and a version with a roof and without a roof.
The Oriel window with a glass roof above is a 100% bonded system that requires specialist installers as this is a technically challenging fit. The framed oriel window is simpler using a slimline aluminum frame and the window can also sit on a cill. A less complex installation is required here.
6 top tips for homeowners and architects when choosing oriel windows and frameless box windows
- Plan early: Incorporating oriel windows requires precise design and preparation. Working with architects and builders early ensures smooth installation.
- Planning permission: Check if planning permission is required
- Location: Check which direction your oriel window will face to consider the amount of light and solar heat gain and if you are being overlooked!
- Consider glass options: Choose the correct glass specification to balance light, thermal performance, and aesthetics.
- Research experienced installers: These windows require specialist structural glazing and installation expertise. Check out your installer’s previous projects.
- Building Regulations: Check that your installer is complying with Building Regulations.
- NEVER buy these windows on a supply-only basis for DIY fitting. Expert installation is required every time.
Oriel windows and frameless box windows represent the pinnacle of modern architectural design. Combining structural ingenuity with aesthetic appeal, they offer a versatile and customisable solution for enhancing any building.
Whether you want to add a striking feature to a contemporary home or update a traditional property with modern glazing, these windows provide endless possibilities.
If you would like help and advice choosing the right oriel windows and installer for your project, please get in touch.
For impartial advice and expert insights, explore the Door and Window Experts website—the UK’s leading resource for everything you need to know about windows and doors.
Image Thanks, Suppliers and Acknowledgements
Trade Supply and supply only of Oriel and Frameless Box Windows.
Glideline Ltd, based in Great Yarmouth are not only one of the most experience Cortizo systems manufacturers, but also provide frameless, oriel and box windows.
John Knight Glass is an excellent and established business that serves Liverpool, Cheshire, Chester, North Wales, and the surrounding areas. This company has extensive expertise in this type of window design. Here’s their Cheshire project featuring their oriel window creations.
HBD Systems are also very well known to this website and is another exceptional installer of windows and doors serving London, Hertfordshire and the Home Counties. The projects carried out by HBD Systems are first-class and worth seeing.
IQ Glass is one of the UK’s leading installers of advanced windows and doors and some of the most technically challenging structural glazing, structures, and bespoke designs. The IQ Glass Project Portfolio perfectly demonstrates the business’s expertise, trustworthiness and reputation. Featured image by IQ Glass.
