Bay windows have been around for centuries. Unlike conventional windows that fit flush to the wall, bay windows protrude outwards, thus forming a bay within the room.
You’ll find bay windows on all sorts of stately homes and period properties. Sometimes, the bay is filled with a sofa or sitting area so people can sit in the window – hopefully with a good view – and enjoy plenty of natural light from the outdoors.
However, bay windows are also popular in towns and cities as they’re a clever way of increasing interior space. And of course, from the exterior, they look great and add a touch of class to the property.
This article will cover how much you can expect to pay for bay windows in the UK, factors that affect the cost, and other common questions surrounding their use.
Average Costs of Bay Windows
By collecting quotes from 7 primary sources and 6 secondary sources, we discovered the following quotes for bay windows. Prices include VAT.
Windows and labour
Labour costs will vary, with some suppliers including them at an all-in-one price (e.g. companies like Everest). Prices assume minimal alterations to the window aperture (opening).
| Material | Small Bay Window (1 to 1.5m) | Medium Bay Window (1.5m to 2.5m) | Large bay window (2.5m to 3.5m) | Extra-Large Bay Window (3.5m+) |
|---|---|---|---|---|
| uPVC | £600 - £1,000 | £1,000 - £1,800 | £1,800 - £2,500 | £2,500 - £7,500 |
| Steel | £800 - £1,200 | £1,200 - £2,000 | £2,000 - £2,750 | £2,750 - £7,500 |
| Aluminium | £800 - £1,200 | £1,200 - £2,000 | £2,000 - £2,750 | £2,750 - £7,500 |
| Timber | £800 - £1,500 | £1,000 - £2,250 | £1,800 - £3,500 | £3,000 - £8,000 |
| Labour | +£300 - £750 | +£400 - £850 | +£500 - £1,000 | +£750 - £1,500 |
Extra costs
Here are some extra costs to consider for bay window installations:
| Pitched Roof | +£250 + £500 |
|---|---|
| Adding Weight Bearing Support Wall | +£500 - £1000 |
| Internal Sitting Area | +£350 to £750 |
| Security Shutters | +£500 to £800 |
| Triple-Glazed High End Glass | +25% to 30% of window cost |
Fitting new bay windows will likely cost more than £2,000 for a standard project. Complex projects can easily cost more than £3,000 to £5,000 or more.
A complex project might involve creating a supporting wall to ensure the window can bear weight (e.g. for creating a downstairs bay window seating area).
Factors Affecting the Cost of Bay Windows
Bay windows come in various shapes and formats, but how do they affect the cost?
Window Size
Bay windows come in various sizes, from compact windows for small openings to larger windows for wide openings, e.g. in living rooms.
A small bay window closer to 1,200mm across will likely cost under £800 for a uPVC or steel frame, whereas a very large bay window measuring more than 2,400mm will almost definitely cost upwards of £1,000.
Panels
Bay windows come with multiple panels with a minimum of 3. The number of panels marginally affects cost, but the overall size is the bigger factor. Bowed or curved windows typically need over 5 panels to be effective.
Frame
The frame materials greatly impact the cost of any window. uPVC is the most common and cheapest material, with steel, aluminium and timber frames costing more. A timber frame window might cost some 50% more than a uPVC frame window.
Complexity of Design
If you’re swapping one bay window for another, that’s as simple as it gets. In this case, you’ll pay for the price of the window and probably 2 to 4 days labour for a standard job.
If, however, you’re fitting an entirely new bay window to replace a normal window, the builders will need to fit the window and supports, secure the roof and tile it if necessary, etc. This will cost significantly more.
Roof
A tiled roof will always cost more than a flat roof. Pitched roofs are harder to build and will likely take several days to complete for a large bay window.
Why Install a Bay Window?
Bay windows boast both aesthetic and practical benefits. Some homes have installed them already, so you might be looking to replace an existing window.
But if you’re considering installing a new bay window, or are wondering whether to add one to a new build house, here are the benefits:
Aesthetics
There’s no doubt that bay windows have excellent aesthetic qualities from the inside and outside.
On the outside, they change the overall shape of the house, and from the inside, they allow much more light into the home while adding a statement to any room.
Light
With more glass surface area, bay windows allow more light into the room. This is excellent for brightening up dull or shady rooms.
Views
Bay windows upstairs open up superb panoramic views. Perfect for adding a statement feature to an upstairs bedroom or even a loft conversion.
Types of Bay Windows
Bay windows vary in a few ways:
- Size: You can get small bay windows for bedrooms and large ones for living rooms
- Panels/sides: Bay windows typically come with between 3 and 8 panels.
- Shape: The bay itself can be boxy or rectangular with square sides, or bowed or circular with smooth sides.
- Frame: Like other windows, bay windows can be either uPVC, timber, aluminium or steel.
- Window type: Bay windows can be casement, sash or other types.
Bay windows can be installed off the ground or they might be built into the brick wall. By building the window into the brick wall, it’ll have ample support and will bear weight safely. This is perfect for adding a seat to a downstairs living room bay window, for example.
Floating bay windows can also be built to bear weight, but this is an additional design consideration and you’ll need to discuss it without your builder.
Maybe people wonder whether you can sit on all bay windows; the answer is that it depends on the specific build itself. Many cannot bear weight – so don’t assume you’ll be able to build a cosy sitting area in an upstairs bay window without specifying you want this to your builder.
Bay Window Shapes
There are a few different types of bay window shapes, as follows:
Box
Box bay windows have square, right-angled sides. They form a box shape, which can look good for some modern houses. The entire window, sides and roof can be built from glass – and sometimes even the floor of the window too. This can look quite dramatic on the right property.
Bowed
Bowed bay windows are gently curved in a bow. This rounds off the boxy appearance and suits most houses. They also allow more light in the home and typically have 5 or more sections.
Circular
More or less the same as bowed, but protruding further from the house in a semi-circle rather than a flatter bowed curve.
Oriel
Oriel windows are typically built on the 1st floor and above and are common on period properties. They provide panoramic views and are built into the wall.
Most homes will suit either bowed, circular, or box bay windows. There are plenty of options for these types of windows, so you’ll have a choice of sides, frame material, etc.
Roofing for Bay Windows
Bay windows protrude from the home, and thus, they usually have their own roofs. In some situations, the bay window is built into the wall that extends from the ground to the top floor, where there’ll be no roof.
Bay window roofs can be flat or pitched. Pitched roofs arguably look better, but need to be tiled, which costs more in installation and maintenance. Flat roofs are simpler and cheaper to install.
Building Regulations and Planning Permission For Bay Windows
Replacing an existing bay window with another, assuming no structural works, won’t require Planning Permission. Fitting a new one may require Planning Permission, particularly for projects on the first floor or above.
However, fitting a new bay window at the front of the house effectively counts as an extension and may require Planning Permission in some situations – it’s a bit of a grey area, and local interpretation applies, so always check with the local authority.
Building Regulations also apply:
- Approved Document B – Fire Safety. Windows must sometimes be large enough to escape through.
- Approved Document F – Ventilation. Windows must meet spec to prevent too much condensation.
- Approved Document K- Protection from falling, collision and impact. Glass must be Fensa-approved.
- There are additional regulations for windows fitted on the first floor and above.
Working with a Fensa-certified installer is crucial, as this will help ensure regulatory compliance.
When searching for window installers, look for Fensa and Certass membership and certification. Quality installers will back their work with a guarantee.
Get Prices on Bay Windows Near You
We’ve done our best to give you a good idea of what you can expect to pay for a bay window.
However, our guides are not a substitute for a fixed quote specifically for you.
We work with all the best window installers ready to price your job. Get free, no-obligation quotes in your local area and compare prices using the form below.
- Compare Multiple Quotes & Save Up to 40%
- Certified & Vetted Installers
- Free & No Obligation
- Local Bay Window Experts Near You
To Sum Up
Installing a new bay window can be a complex project, usually costing more than £2,000.
In general, it’s wise to budget more than £2,000 for anything but the simplest projects. Labour costs vary, but the project will likely take a few days to complete.
Installing a new bay window might be most economical when you’re extending or renovating the house.