uPVC Window Replacement Costs for a 3-Bed House (2026 UK Benchmark)
A complete benchmark of turnkey replacement costs for standard 3-bed UK homes, covering factory supply, FENSA certified fitting, and heat loss reduction.
- Standard 3-bedroom UK home typically has 8 to 10 window openings (1 bay/large front, 1 kitchen, 1 dining, 1 landing, 3 bedrooms, 1 bathroom).
- Average turnkey replacement cost in 2026 ranges from £4,200 to £5,800 for white uPVC casement, or £5,800 to £8,200 for flush sash anthracite grey.
- Approved Document L requires minimum whole-window U-value of 1.4 W/m²K (or WER Band B/A+).
- Upgrading from failing 1990s double glazing (2.8 W/m²K) to modern 1.2 W/m²K units saves £160–£230 annually on gas central heating bills.
Key Considerations for UK Property Owners
Replacing aging windows and doors is one of the highest-impact thermal and security upgrades you can undertake. Under Approved Document L1B of the UK Building Regulations, all new replacement windows installed in existing dwellings must achieve a maximum U-value of 1.4 W/m²K, which modern A+ argon-filled double glazing comfortably beats at 1.2 W/m²K.
Beyond thermal performance, installations must satisfy Approved Document F regarding continuous or trickle ventilation, Approved Document K for safety glazing within 800mm of the finished floor level, and Approved Document Q / PAS 24:2022 for secure ground-floor accessibility.
Need an Accurate Turnkey Replacement Quote?
Use our interactive pricing engine to calculate frame costs, FENSA certified fitting, and gas heating savings instantly.
Launch Free Window Calculator