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Cost of Bay Windows Installed

Bay windows are a character feature in millions of homes and attract buckets of natural light - the average cost of a new bay window is around £1,200. However, there are lots of variables to factor into your budget!

One of the key things to look for in your quotations is whether your bay window price includes all the fitting or whether it's a cost solely for the supply of the glazing and frames.

Looking for an accurate cost of a new bay window? Fill out the form below and we'll put you in touch with local window fitters in your area - compare costs for free! Time complete - 30 seconds. 

What is the Average Cost of Bay Windows Installed?

The UK average bay window costs come in at £1,200 for a three-section unit, increasing to £1,650 for four sections and £2,150 for five as an indication.

A bay window can come in lots of sizes, shapes and formations, but the concept is that the window extends outwards from the flat wall of your property, creating additional space, light and extended views.

The variants include rounded bays, bow bay windows or oriel windows, so it isn't easy to pin down an accurate cost estimate without digging a little deeper.

If you're interested in a softer, curved bay window, you could choose a bow window as a slightly alternative structure, with similar prices varying by approximately £50 per project.

Calculating the Cost of Bay Windows Installed

No two properties are identical, so a window fitter will usually want to check the size measurements of your bay window space or attend your home via a scheduled site visit before they can offer a quotation.

That's because pricing depends on whether you have an old bay window you're replacing or want to remove standard windows and create a new structure for bay glazing.

There are four primary bay window styles:

  • Box windows are rectangular with neat, clean lines and precise corners that create an angular addition to your room.
  • Bow windows, which we mentioned earlier, are a smooth rounded shape and tend to produce more natural light with at least four or five sections to generate that gentle outline.
  • Circle windows are like a conventional bow window but updated with a circular, round frame design.
  • Oriel windows are a type of bay, but this is the name given to bay windows on upper floors - normally supported with brackets and installed in bedrooms on higher levels for an expansive view.

It's wise to consult with your local window fitter before you pick a style if you're unsure which to go for, as they will be able to share images of similar past projects so you can get a feel for the bay window layout best suited to your home.

Cost Factors in Replacing Your Bay Windows

The window style is just one cost element that feeds into your total bay window budget. Other factors that will change the price of your bay windows include:

  • The size of the window - bay windows are a great way to make smaller, darker rooms lighter or add depth to homes with lower ceilings.
  • How many sections you choose - curved bay windows necessitate more panels to produce a rounded effect. The more units you have, the more expensive your bay windows are.
  • Which materials and the quality you go for. Like every modern window, there are several material choices, colours and finishes at various price points.
  • The level of structural work required. The simplest option is replacing an old bay window with a like-for-like unit. However, if you're removing standard windows and building a bay, your contractor may need to price up structural work while expanding the opening.
  • The design complexity - non-standard window sizes, bespoke frames, unusual colours and intricate installation will all drive up your bay windows cost.
  • Location matters because home improvement works in the southeast, and London almost always costs more than other regions.

Homeowners with an exact budget can consult a window fitter to determine which choices will comply with their spending maximums or identify solutions with the right design feel without spending over the odds.

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Average Bay Window Costs By Size and Design

Bay and box windows are the most popular options, so we've summarised the UK average costs depending on the number of sections you require.

Number of sections Average bay window cost Average box window cost
Three £1,250 £1,250
Four £1,650 £1,650
Five £2,150 £2,100

As we've mentioned, there isn't a big price differential between these two related styles, so the bigger cost variances come when comparing different bay window frame materials.

Most bay windows come in a standard white UPVC - it's low cost, easy to maintain, and highly durable.

While basic white may be common, it is far from the only colourway available, and UPVC frames can be designed in multiple finishes, including a timber frame effect.

Genuine wood is also a viable option for bay window frames and looks fantastic on older properties but does require a fair amount of upkeep. Wooden window frames need to be treated and varnished every couple of years to remain in good condition.

A third option is to consider aluminium, which can be powder coating in different shades. Aluminium windows are sleek and modern and provided you get properly treated glazing, they can be as energy-efficient as UPVC.

The Benefits of Installing a New Set of Bay Windows

Bay windows have a certain charm that can be a great selling point if you come to move - but they also have a range of advantages in terms of security, insulation and living space.

From the outside, a bay window is elegant. Still, it has an array of material and design options to complement a modern property - grey UPVC frames, for example, have a contemporary feel.

Internally, a bay window maximises the area inside your room; in the same way, a Velux window in your attic can make a tight space feel significantly larger.

The rounded multi-panel construction increases the flow of natural light considerably, compared to standard flat panelled windows, and means you get better views of your outdoors.

Other advantages include:

  • Improved ventilation - there are numerous ways to structure your bay window, with easy-open panels to ensure you have a good flow of clean air through your home.
  • Low maintenance - a quality window will last for decades, and most bay windows will come with a guarantee of around 20 years.
  • Efficient - double or triple-glazed panels prevent heat from escaping, and you can have glass treated with low emissivity coatings, toughened laminate or soundproofing.
  • Secure - modern locking systems are highly effective, and the steel frame inside each window unit makes them robust.
  • Weatherproof - provided your bay window is installed professionally, it will be weatherproof and able to withstand even extreme conditions.

Many homeowners install a storage cabinet or bench underneath the arch of the bay in a living room or use the room as a dressing table space to make the most of the extra area.

Checkout this fascinating time lapse video of a uPVC bay window installation to give you a sense of what's involved:

Frequently Asked Questions - What is the Cost of Bay Windows Installed?

Next, we'll run through the common questions we receive about the average cost of bay windows installed.

Why Are Bay Windows So Popular?

A bay window projects out from the exterior wall of your home, creating a rounded bay space on the inside. You can use bay windows in living rooms and downstairs areas or on higher floors, typically to extend a bedroom. There are many design options, with typical bays either square or polygonal with multiple sides - the more panels you have, the more curved your finished bay window will be. The big selling point is that bay windows make a room lighter and brighter, free up extra space, and normally add value to your property if you ever decide to sell.

What Materials Can I Choose From for a Bay Window?

UPVC is the most common bay window material used for all modern double-glazing window types - but it's not the only option! Lots of people go for UPVC because it is cost-effective, highly efficient and easily available, and a coloured or timber effect frame can replicate natural materials well. Timber remains a possible option, and although treated hardwood can be fairly pricey, it looks exceptional when kept in good condition with regular maintenance and varnishing. The third material type is aluminium, which is strong and resilient and has excellent insulation properties.

Are There Any Negatives to Fitting a Bay Window?

Installation times for a bay window can be slightly longer than for more basic structures since your window fitter will need to place several panels alongside each other. The extra light flooding your property can also make it a little hotter inside during the summer - a UV glass protection coating or simply opening the smaller upper windows will help regulate the warmth. Generally, the more glass you have, the lower the overall energy efficiency of your home, so it's worth using double-glazing or triple-glazing (which would be the standard in any new installation).

How Can I Maximise the Insulation of My Bay Windows?

As discussed above, double glazing is preferable to single panelled glass and will ensure you don't lose insulation properties when you replace your windows. Another great solution is to use floor to ceiling curtains at night, which can add slightly to the energy-efficiency performance of a larger bay window. The easiest option is to go for triple-glazing and ask your window fitter for the highest energy-efficiency glass they have available.

How Does the Price of a Bay Window Compare to Other Styles?

Bay windows look great but aren't the cheapest type of window, primarily because the structure is more detailed and requires multiple smaller glazing panels. If you're on a tight budget and want to compare the costs of various windows, we've listed some of the most common below on a supply only basis.

Window style Average cost per window
Bay £1,000 - £1,300
Casement £150 - £575
Sash £550 - £850
Tilt and turn £450 - £600

How Do Bay Windows Open and Close?

Although the aesthetic impact of a bay window is somewhat different from other types, the functionality is very similar to a series of casement or sash panels. Casement windows open outwards or inwards on a side hinge, whereas a sash window slides up and down inside a frame. Some bays have a combination of fixed windows without an opening and then sash or casement fixtures on the smaller upper frames - there are lots of design options!

How Much is the Cost of Bay Windows Installed?

As we've seen, multiple variables will dictate your budget, including the size of the window, the material you choose, which glazing you'd prefer and how many panels you have built-in. Most bay windows start at £1,200 for a simple installation and can go anywhere upwards of £8,000 if you select a high-end material frame, treated or reinforced glass and sash window openings. UPVC is the cheapest material option and is the most widely available on the market, but timber and aluminium or a composite blend can also work well. Period properties and those in conservation areas normally opt for timber since there may be limitations on the alterations you can make to the exterior of your home. If you'd like a specific price, we'd recommend comparing quotes from three or more local suppliers and checking for a breakdown of what work is included within that cost.

How Expensive is a Large Bay Window?

The size of your window will undoubtedly affect the price.  If you decide on a UPVC bay window, you might be looking from £1,000 to £1,300 for a 250 cm x 150 cm white frame, with three panels included. If your opening is 300 cm x 150 cm, you'll likely need four panels, which costs from about £1,400 to £1,700, increasing again to £2,000 - £2,500 for a five-panel bay window across a 400 cm x 150 cm space. Adding coloured or wood grain effects will normally bump up the price by about 10% to 20% as an average.