Updated June 2026 · CW Doors & Windows
A complete guide to replacement house windows
Choosing replacement windows is a £4,000–£10,000 decision that most homeowners only make once or twice. This is the full guide we give our Leicester customers — frame materials, glazing specs, costs and what to prioritise.
Frame material — uPVC, aluminium or timber?
uPVC: cheapest, lowest maintenance, 20–25 year lifespan. Covers 90% of UK homes for good reason.
Aluminium: slimmer sightlines, more expensive (50–70% premium), best for large picture windows and modern extensions.
Timber: best for conservation areas and period properties. Higher maintenance (repaint every 6–10 years).
Glazing — double or triple?
Standard A-rated double glazing handles 95% of UK homes. U-value around 1.2 W/m²K.
Triple glazing makes sense on north-facing elevations or properties on very noisy roads. Costs about 25% more.
Always specify warm-edge spacer bars (reduces condensation) and laminated inner pane on ground-floor windows for security.
Cost ranges in Leicester (fully fitted)
Single casement window: from £450.
3-bed Leicester semi (typical 8–10 windows): £4,500–£8,000.
Larger detached property (12–16 windows): £8,000–£14,000.
Coloured frames add ~10%, triple glazing adds ~25%, sash windows add 40–60%.
Building Regulations and FENSA
All replacement windows must comply with Document L (energy efficiency). Your installer must be FENSA or Certass registered and will lodge the certificate automatically.
Without this paperwork, the windows are technically non-compliant and can cause issues at point of sale.
Planning the whole house
Many customers replace windows in stages, starting with the front elevation or the worst frames. That is fine, but ask for the same range and colour so later windows match. We keep a record of what we fitted so a second phase lines up.
Windows start from £450 fully fitted. The survey is free, measured within 5 days, and the quote is in writing with no hidden costs.
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