New windows change how a home looks, feels and performs. The cost of window replacement in the UK depends mainly on style and size: a standard uPVC casement window usually costs £400 to £900 fitted, while sash windows, bay windows and tilt-and-turn designs cost more. Choosing well also improves energy savings, security and ventilation for decades.
This guide focuses on the window options available, what each style costs, the rules that apply to replacement windows, and what happens on fitting day, so you can plan the project with confidence.
Window styles and typical prices
Example: a three-bedroom semi
| Item | Indicative cost |
|---|---|
| 7 standard uPVC casement windows | £3,500–£5,500 |
| 1 bay window | £2,000–£3,500 |
| Removal, disposal and making good | Usually included |
| Typical total | £5,500–£9,000 |
Choosing the right windows for your home
- Match the period: sash or flush casements suit older houses and can protect resale value.
- Check performance: look for an A-rated BFRC label or a low U-value.
- Think about cleaning: tilt-and-turn or easy-clean hinges help on upper floors.
- Consider noise: acoustic or laminated glass helps on busy roads.
- Colour and finish: foiled or coloured frames cost more but avoid the “plastic” look.
Rules that apply to replacement windows
- Energy performance: replacement windows must meet minimum thermal standards.
- Escape windows: upstairs bedrooms and some ground-floor rooms may need an opening large enough for escape in a fire.
- Ventilation: trickle vents are often required, especially if existing windows had them.
- Planning: usually not needed for like-for-like replacements, but listed buildings, flats and conservation areas can have restrictions.
- Certification: a FENSA or Certass registered installer can self-certify and register the work.
What happens on fitting day
A typical house takes one to three days. Installers usually remove and replace one window at a time so rooms are never left open for long. Expect some dust and minor plaster or paint touch-ups around reveals. Before they leave, check every window opens, locks and seals properly, and ask for the keys to the locking handles.
Security tips
Ask for windows tested to the police-backed Secured by Design or PAS 24 security standard, with multi-point locks, internally glazed beads and laminated glass on vulnerable ground-floor windows. Some home insurers offer lower premiums for certified locks.
Prices reflect typical UK window installer quotes; rules summarised from building regulations guidance.
Independent guide – not linked to any window manufacturer or installer.