Bay Windows, Beautiful, Made-to-Measure Bay Window Installation
Turn a flat, tired elevation into a striking bay window that adds light, space and lasting value. Flush Sash UPVC handles it all, structurally surveyed, made to measure, and backed by a 10-year guarantee.
- Wide choice of styles and colours
- Competitive costs, no hidden fees
- 10-year guarantee, total peace of mind
25+ years in business
Certified installers
1000+ Home installations
10 Year guarantee
What Is a Bay Window?
A bay window is a window that projects outward from the main wall of your home. It follows the wall’s angle rather than sitting flush against it. Most bay windows are built around a central fixed sash. They are flanked by two angled side windows that open.
This gives you a wider field of view, more natural light, and genuine extra floor space inside the room. It’s this combination of light, space, and kerb appeal that makes bay windows one of the most requested upgrades on both period and modern homes.
Bay vs Bow Windows: What’s the Difference?
Bay and bow windows are often mentioned in the same breath, but they’re built differently. A bay window is angular and typically has three panels. It has a large fixed centre pane flanked by two side panels. These are set at a sharp angle, commonly 30° or 45°, forming a projecting box shape. A bow window curves rather than angles. It is made up of four, five, or six identical units.
These are set at much shallower angles, around 10° each, to form a gentle, rounded arc. Because of the wider angle, a bay window tends to create a deeper internal alcove. This is ideal for a window seat or storage nook.
A bow window projects less into the room but spreads a wider, more continuous sweep of light and view across its multiple panes. Bay windows are also generally simpler and slightly more cost-effective than a curved bow configuration. This is because they use fewer individual units.
How a Bay Window Is Built (Fixed Sash, Side Panels, Couplers)
Every bay window is built from individual units joined by couplers into one structurally sound unit. A fixed central sash gives maximum strength and the tightest seal, flanked by two angled side panels, casement, flush casement, sash, or tilt-and-turn, usually operable for fresh air.
The units lock together with corner couplers or bay poles, then cap the top and bottom with a headboard and seatboard for a rigid assembly. Since a bay window projects outward, it needs proper structural support, which is why we always start with a structural survey.
Bay Window Materials and Styles
The material and shape you choose shape how your bay window looks, performs, and lasts. From energy-efficient uPVC to sleek, modern aluminium, each option brings a different balance of cost, style, and maintenance. Below, we’ve broken down the choices so you can weigh them against your home and your budget. We’ll help you land on the right fit either way.
uPVC Bay Windows
uPVC is the most popular material for bay window installations, and for good reason: it’s affordable, low-maintenance, and can achieve A++ energy ratings thanks to a multi-chambered profile that traps heat far more effectively than older, single-chamber frames. It won’t rot, warp, or need repainting, which makes it a long-term choice for most homes.
Aluminium Bay Windows
Aluminium bay windows use slimmer sightlines than uPVC, which maximises the glass area and lets in more daylight, a real advantage on a bay, where the whole point is to open the room up. The frames are strong enough to support larger bay configurations, finished in a powder-coated RAL colour of your choice, and tend to suit contemporary or new-build properties.
Bay Window Replacement, Is It Time to Upgrade?
Signs Your Bay Window Needs Replacing
If your bay window is letting in draughts, showing condensation trapped between the panes, or has frames that are cracked, warped, or difficult to open and close, it’s a sign the seals or the unit itself have failed.
Other warning signs include visible frame rot, structural sagging, water leaks or staining around the seatboard, foggy or discoloured glass, and rising energy bills as the projecting structure loses more heat than a flat window. Discoloured or yellowing uPVC and outside noise becoming more noticeable indoors are also common indicators that it’s time for a bay window replacement.
Converting a Flat Window into a Bay Window
It’s possible to convert a standard flat window into a bay window, turning a single flat opening into a projecting, made-to-measure structure. This is a bigger job than a like-for-like replacement. It involves removing the existing window and frame, building a floor or brick support base beneath the new projection, fitting a load-bearing header above the opening, and adding a small roof canopy to shed water from the new structure.
Because of the structural work involved, it starts with the same structural survey as a new build bay installation. This confirms what foundation and support work is required, ensures insulation is specified correctly, and checks that any necessary planning permission is in place before manufacture and fitting.
Start your Project Today
Take the first step towards a more comfortable, secure, and better-looking home. Whether you’re replacing a single window or upgrading your entire property, our team makes the process simple from start to finish. You’ll get expert advice, tailored designs, and clear pricing with no pressure.
Colours
Handles
Cills
Obscure Glass
Glazing Options
Colours, Finishes & Cost
Whether you prefer traditional elegance or contemporary styling, our flush sash windows are available in carefully selected finishes designed to enhance your home’s character. Popular options include white, cream, anthracite grey, black, chartwell green, and realistic woodgrain effects. These durable finishes help maintain their appearance while supporting a cohesive design across your property.
Window Cills for Protection & a Perfect Finish
Choosing the right glazing can transform how your rooms feel and function. Flush Sash uPVC offers a range of decorative, obscure, and specialist glass solutions that help balance privacy, daylight, aesthetics, and security while complementing the architectural style of your property.
95mm Cill
Ideal for standard installations where minimal projection is required while maintaining effective weather protection and a neat finish.
150mm Cill
A versatile option suitable for many residential properties, providing additional projection and improved water management.
180mm Cill
Popular for deeper wall constructions and renovation projects where greater coverage and protection are needed.
250mm Cill
Designed for properties requiring substantial projection, making it suitable for deeper reveals and rendered walls.
Handles that complete the Look
Hardware is often the finishing detail that defines a window’s character. Our carefully selected handle collection combines aesthetics, comfort, and durability. Available in traditional and contemporary designs, these options allow homeowners to coordinate windows with existing doors, architectural features, and interior décor.
White OS
Satin OS
Chrome OS
Graphite OS
Bronze OS
Black LL
Antique Black OS
Gold OS
Chrome MT
Gold MT
Antique Black MT
Graphite MT
Chrome TD
Graphite TD
Antique Black TD
Gold TD
Glass Choices for Privacy and Natural Light
Choosing the right glazing can transform how your rooms feel and function. We offer a range of decorative, obscure, and specialist glass solutions that help balance privacy, daylight, aesthetics, and security while complementing the architectural style of your property.
Advanced Glazing for Better Performance
Modern glazing technology plays a major role in comfort, efficiency, and noise reduction. Our glazing solutions help create a quieter, warmer, and more energy-efficient home while supporting long-term performance and reducing heat loss throughout the year.
Triple
Glazed
Laminated
Glass
Square
Lead
Diamond
Lead
Internal
Georgian Bar
Enjoy Privacy without The Maintenance with Integral Blinds
Integral blinds are permanently sealed within the double-glazed unit, offering a stylish, maintenance-free solution for light control and privacy. Unlike conventional blinds, they remain protected from dust, moisture, and everyday damage, keeping them looking clean for years. Ideal for busy family homes, integral blinds combine modern convenience with improved energy efficiency and a sleek, uncluttered appearance that perfectly complements flush sash windows.
Book a Free Home Survey
Provide us details about your project.
How Much Does a New Bay Window Cost?
As a general UK guide, a like-for-like bay window replacement typically costs between £1,200 and £4,000, with most homeowners paying around £2,000 for a standard 3-panel uPVC bay on the ground floor, supplied and fitted. If you’re converting a flat wall into a brand-new bay window from scratch, costs rise significantly, usually £4,000 to £10,000+ because of the structural work involved, including lintels, foundation support and roofing.
What Affects Bay Window Pricing
Bay window cost depends on the size and number of window units in the bay, the shape you choose (splay, box or circle), the material (uPVC or aluminium), the glazing spec (double or triple glazing, Low-E coatings), and any extras such as Georgian bars, leaded glass or a non-standard colour finish. The complexity of installation, including any structural alterations, lintels or support work, and regional labour costs can also affect the final price, and converting a flat wall into a new bay will always cost more than a like-for-like swap.
Getting an Accurate Bay Window Quote
Because every bay window is made to measure, the only way to get an accurate price is with a free home survey. We’ll measure the opening, assess the structural support needed, and talk through material and style options before giving you a fixed, no-obligation quote.
Why Choose Us for Your Bay Window Installation
We handle every bay window from survey through to manufacture and fitting, so nothing is left to chance. Here’s what sets an installation with us apart.
Made-to-Measure Precision
Every bay window we install is manufactured to your exact opening, not adapted from a standard size. A full structural survey comes first, so the frame and support work are planned around your property. The result is a fit, seal and finish that’s precise from day one.
Energy-Efficient, A-Rated Glazing
Our bay windows use double or triple glazing with Low-E coatings, keeping heat in and draughts out. Multi-chambered uPVC and thermally broken aluminium profiles reduce heat loss further. A to A++ Window Energy Ratings are achievable depending on spec.
PAS 24 & Secured by Design Security
Every bay window is fitted with multi-point locking as standard, securing the frame at more than one point. It can also be specified to PAS 24 and Secured by Design standards on request. That’s certified security without compromising on light or views.
10-Year Insurance-Backed Guarantee
Every installation is backed by a 10-year, insurance-backed guarantee covering workmanship and product. That protection holds even if our business were ever to stop trading. Your investment stays protected long after our fitting team has left.
Recent Bay Window Installations
Take a look at some of our recent Bay Windows installations. Each project reflects our focus on quality, detail, and design.
Ready to Transform Your Home with a New Bay Window?
A bay window is one of the few upgrades that changes how a room feels from the moment it’s fitted: more light, more space, more kerb appeal. Whether you’re replacing a tired, draughty bay or converting a flat window into one for the first time, our team handles it from survey through to fitting, backed by a 10-year insurance-backed guarantee. Get a free, no-obligation home survey and find out exactly what your new bay window will cost, with no pressure and no hidden fees.
FAQs
Common questions we are asked the most about bay & bow windows
How much does a new bay window cost?
As a general guide, a like-for-like bay window replacement typically costs between £1,200 and £4,000, with most homeowners paying around £2,000 for a standard 3-panel uPVC bay on the ground floor. Converting a flat wall into a brand-new bay window costs more, usually £4,000 to £10,000+, due to the structural work involved. Your exact price is confirmed after a free home survey, reflecting your opening, chosen material, and any structural work needed.
What is the difference between a bay window and a bow window?
A bay window is angular, following straight lines out from the wall and typically adding more interior floor space, while a bow window curves in a gentler arc using four or more identical units and projects less from the wall.
Do bay windows add value to a house?
Bay windows are widely seen as a premium feature that adds kerb appeal, extra light from multiple angles and additional floor space, all of which are commonly cited as factors that can support a property’s value. That said, it’s a significant investment, and the cost isn’t always recouped pound-for-pound in a valuation; the main return tends to be in kerb appeal, comfort and how the home shows to buyers.
Do I need planning permission for a bay window?
It depends on the location and whether it’s new or a replacement. Adding a brand-new bay window to the front of a house usually requires planning permission, since it projects outward like a small extension. Replacing an existing bay window, or adding one to the side or rear of the property, usually falls under permitted development, but it’s always worth confirming with us at the survey stage, particularly on listed buildings or in conservation areas.
How long does bay window installation take?
A straightforward, like-for-like bay window installation typically takes half a day to a full day (around 4-8 hours) for our fitting team, once your made-to-measure unit has arrived. If the project involves major structural work, such as new lintels or additional support, the on-site installation can extend to 2-3 days.
Are bay windows energy efficient?
Yes, modern bay windows use double or triple glazing, Low-E glass coatings and multi-chambered uPVC or thermally broken aluminium profiles, which together can achieve A to A++ Window Energy Ratings. Because a bay window projects outward, it exposes more surface area to the outside than a flat window, so proper insulation beneath the seatboard and at the joints is essential to get the most from it, something we account for at the survey and manufacture stage.
Can I convert an existing window into a bay window?
Yes, an existing flat window can be converted into a bay window, though it’s a bigger job than a straight swap. It requires cutting into the wall, fitting a new load-bearing header, building an exterior support base, and adding a small roof canopy, all confirmed by a structural survey before manufacture begins.