If you’re wondering, “What is a bay window?” think of it as a window that extends outward from your home, creating a small alcove or “bay” inside. This classic feature combines three panes — one central window with two angled side panes — to form a semi-projection that adds both light and space to a room.
Bay windows have been popular in Britain since the Victorian era, valued for their elegance, panoramic views, and the cosy interior seating space they often create. While they tend to be more expensive than standard flat windows, they can dramatically enhance kerb appeal and make a living area feel brighter and larger.
What materials are bay windows made from?
Like most modern window types, bay windows are available in three main materials:
- uPVC – the most affordable option at around £2,250 per unit, low-maintenance and widely available.
- Aluminium – a mid-range choice at around £4,500 per unit, offering a sleek modern finish and good durability.
- Timber – the premium option at around £6,700 per unit, with a traditional aesthetic that suits period properties, but requiring regular maintenance.
Because bay windows are large and complex to install, prices are usually given per unit, rather than for a full property. It would be unusual — and very expensive — to have every window in a home as a bay.
How much do bay windows cost?
Bay windows are among the most expensive types of windows because they effectively combine three (or more) windows into a single unit. A typical bay will include one central pane with two angled side panes, though costs vary by size, material, and glazing choice.
On average, homeowners can expect to pay:
- uPVC bay windows – from £2,250 per unit
- Aluminium bay windows – from £4,500 per unit
- Timber bay windows – from £6,700 per unit
How Long Do Bay Windows Last?
- uPVC: around 20–25 years with minimal upkeep.
- Aluminium: up to 45–50 years, resistant to warping or rot.
- Timber: 40+ years if properly maintained with regular painting or varnishing.
The larger structure of a bay means that installation quality is critical — poor fitting can shorten the lifespan and lead to draughts.
Are bay windows energy efficient?
When newly installed, bay windows are as efficient as other double-glazed designs, keeping the heat in while letting in natural light. Over time, however, older timber bays may become draughty as the frames shift or degrade.
Bay windows also let in a lot of solar heat gain during summer, which can be uncomfortable in heatwaves. That said, modern glazing options and blinds can help manage this.
In winter, as the windows age, they may become more draughty. No matter how well they are installed, windows are a place where heat escapes from homes, although there are ways to minimise this.
|
Material |
Casement cost for an average 3-bed |
Bay cost per window |
Sash cost for an average 3-bed |
Tilt and turn cost for an average 3-bed |
Bow cost per window |
|
uPVC |
£4,500 |
£2,250 |
£6,500 |
£5,900 |
£2,250 |
|
Timber |
£14,000 |
£6,700 |
£18,000 |
£18,000 |
£6,700 |
|
Aluminium |
£9,600 |
£4,500 |
N/A |
£12,000 |
£4,000 |
What styles of bay windows are available?
There are two main types of bay windows commonly fitted in UK homes:
- Splay bay windows – the most common style, with side panes set at around a 45° angle to the central pane.
- Box bay windows – built at a 90° angle, forming a square “box” shape that protrudes from the property.
Bay windows can incorporate different opening styles, typically sash windows or casement windows, depending on the property and homeowner’s preference.
Bay window pros:
- More natural light – their projection design floods rooms with daylight, boosting mood and reducing reliance on artificial lighting.
- Extra space – the alcove they create inside the room can be used for seating, storage, or decorative purposes.
- Kerb appeal – bay windows are a striking architectural feature that can add character and value to a property.
Bay window cons:
- Cost – significantly more expensive than standard flat windows.
- Temperature control – can let in excess heat in summer and become draughty in winter if poorly maintained.
- Complex installation – requires skilled fitting, which can add to both time and expense.
What to look for in a bay windows quote
Once you’ve decided to buy your windows, you’ll want to get a few quotes together. You can use our expert tool to get prices in your area.
Your quote will be influenced by a few different factors including: how many windows you want, their shape and location, what materials you have chosen, and where you are in the country.
Windows will cost you more in London because the area commands higher wages for tradespeople, for instance.
Firstly, you will want to go through the quote with a fine-tooth comb. What have they included? Has anything been missed out? Is scaffolding in there? Do you need scaffolding? How long have they quoted for? Is that enough or too long?
Does the quote include the finish, colour, locks and handles you asked for?
If you have opted for in-house financing, which you should probably try to avoid since it will be more expensive than other loans, is the deal exactly as the salesperson described?
If there are any discrepancies between what you asked for and what’s in the quote, raise that now and use it as leverage for a discount. If the detail is not there, ask for it.
You will also want to check exactly what the guarantee covers so you can compare it to other deals.
How to get the best price for your new bay windows?
In a word, haggle. There are hundreds of window fitters in the UK and there will be dozens in your area. If you offend one by asking for a cheaper price, so what? Be bold.
Haggling is something of a lost art in the UK, since so much is bought online or in shops where no room for negotiation is allowed.
But for big purchases like cars, homes, windows and renovations, it can save you thousands of pounds.
The key thing is to understand your own priorities and those of the fitter.
