Window styles
Triple glazed bay and bow windows
Bays are common on 1930s semis and Victorian houses, and they lose a lot of heat because they are mostly glass. Triple glazing a bay makes a noticeable difference to the room. The important part is structural: old bay frames are often holding up the brickwork or roof above, and replacement frames may need bay poles.
Summary
A bay window projects out from the wall in angled sections; a bow window curves in more, shallower sections. Triple glazed bays are built as several windows coupled together, and because many bay frames carry part of the wall or roof above, the structure has to be checked and supported before the old frames come out.
What you get
| Configurations | 3-light and 5-light bays, bows, square bays |
|---|---|
| Structure | Load checked; bay poles or support fitted where needed |
| Couplings | Angled or curved couplers between frames |
| Glass | Triple unit, argon filled, two low-e panes |
| Frames | uPVC, aluminium or timber |
| Typical lead time | 5 to 8 weeks |
Guide prices
Guide prices per window, supply and fit, including removal of the old window.
3-light bay
three windows, about 2.7 m across
£2,995 – £3,795inc VAT · £2,495 – £3,160 ex VAT
- Triple glazed throughout
- Old frames removed and taken away
- Fitted, sealed and made good
5-light bay or bow
five windows, about 3.5 m across
£3,795 – £4,695inc VAT · £3,160 – £3,910 ex VAT
- Triple glazed throughout
- Old frames removed and taken away
- Fitted, sealed and made good
Two-storey bay
ground and first-floor bays
£5,995 – £7,495inc VAT · £4,995 – £6,245 ex VAT
- Triple glazed throughout
- Old frames removed and taken away
- Fitted, sealed and made good
Guide prices, supply and fit. The written quote after your survey fixes the price for the specification shown; anything extra is agreed with you first.
Is it right for your home?
A good fit for
- 1930s semis and Victorian bay fronts
- Cold front rooms
- Two-storey bays replaced in one visit
Think twice if
- Bays with visible cracking above, which need a structural engineer first
- Listed buildings
Options
- Matching top-hung or casement layouts
- Bay poles hidden in the couplers
- Leaded or bar designs to match
- Coloured or woodgrain finishes
- Window boards and making good
The structural check
Before quoting a bay, the surveyor looks at what sits above it. Where the old frames are load-bearing, the new frames are fitted with bay poles or another support, so the weight goes through the structure and not the uPVC. If there is cracking or movement, we will recommend an engineer before going further.
Two-storey bays
Many 1930s semis have a bay on both floors. Replacing them together means one set of access equipment and a matched finish. Upper bays may need a tower or scaffold, which is quoted separately when needed.
Building Regulations by nation
| Nation | Replacement windows | Sign-off |
|---|---|---|
| England | 1.4 W/m²K, or a Window Energy Rating of band B or better | Competent person scheme or building control |
| Wales | 1.4 W/m²K, or a Window Energy Rating of band B or better | Competent person scheme or building control |
| Scotland | 1.6 W/m²K | No building warrant for a straight replacement; must meet the standards |
| Northern Ireland | 1.6 W/m²K, or a Window Energy Rating of band C or better | No building notice for a straight replacement; must comply |
Full regulations guide, with sources →
Questions about bay and bow windows
How much does a triple glazed bay window cost?
Our guide starts at £2,995 for a three-light uPVC bay, fitted and inc VAT; UK quotes run from about £2,000 to £4,500.
Do bay windows need bay poles?
If the old frames carry load from above, yes. We check on survey and include support in the quote where needed.
Can I change a bay to a flat window?
That is a structural and planning change, not a like-for-like replacement. Ask and we will explain what it involves.
Will the bay be warmer?
Yes. Replacing old double or single glazing in a bay with triple glazing cuts heat loss through the glass and makes the glass surface warmer, so the room feels less draughty.
Related products
Casement windows
From £695The standard side- or top-hung UK window, with a three-pane unit.
Learn more →
uPVC windows
From £695The lowest-cost way to get three panes of glass, in white or a woodgrain finish.
Learn more →
Whole-house replacement
From £5,695Every window and door replaced in one planned visit.
Learn more →
Period homes and conservation areas
From £1,295Heritage-style frames, and straight advice on what your council will accept.
Learn more →Bay and bow windows by area
England
- Bedfordshire
- Berkshire
- Bristol
- Buckinghamshire
- Cambridgeshire
- Cheshire
- Cornwall
- County Durham
- Cumbria
- Derbyshire
- Devon
- Dorset
- East Riding of Yorkshire
- East Sussex
- Essex
- Gloucestershire
- Greater London
- Greater Manchester
- Hampshire
- Herefordshire
- Hertfordshire
- Isle of Wight
- Kent
- Lancashire
- Leicestershire
- Lincolnshire
- Merseyside
- Norfolk
- North Yorkshire
- Northamptonshire
- Northumberland
- Nottinghamshire
- Oxfordshire
- Rutland
- Shropshire
- Somerset
- South Yorkshire
- Staffordshire
- Suffolk
- Surrey
- Tyne and Wear
- Warwickshire
- West Midlands
- West Sussex
- West Yorkshire
- Wiltshire
- Worcestershire
Scotland
Bay and bow windows: get your guide price
Use the guide-price tool, or book a free survey for a written quote that fixes the price.