Double glazing prices in London and Hertfordshire vary far more than most price-comparison sites admit. As a rough guide, a standard A-rated uPVC casement window is typically £550-£900 supplied and fitted, a uPVC sash window £900-£1,600, and a large aluminium picture window £1,200-£2,500. A whole-house replacement on an average three-bed semi usually lands between £5,000 and £9,000 for uPVC, or £9,000-£15,000 for aluminium.
The material is the biggest single driver. uPVC remains the best-value choice for most homes - A-rated as standard, low-maintenance, and available in woodgrain finishes that suit period properties. Aluminium costs 40-70% more but gives you slimmer sightlines and structural strength for larger openings, bi-folds and roof lanterns. Triple glazing adds roughly 15-25% on top of a double-glazed unit and is worth it for noisy roads or north-facing rooms.
Style matters too. Sash windows cost more than casements because of the sliding mechanism and heritage detailing. Bay windows add structural work. Coloured or foiled finishes typically add 10-15%. Anything non-standard - shaped heads, Georgian bars, obscure glass, integrated blinds - should be priced line-by-line, not lumped into a headline figure.
Fitting and compliance are where cheap quotes quietly fall apart. A proper installation includes making good internally and externally, disposal of the old frames, FENSA certification, and a written 10-year guarantee. Skip any of those and the saving disappears the first time you have a leak, a failed sealed unit or a building-control query on sale.
The single biggest protection against surprises is a proper technical survey. Every Lifetime Glazing quote starts with a free home visit, followed by a technical surveyor's measure-up before manufacture. Because our uPVC and aluminium frames are made to order in the UK, the price you're quoted is the price you pay - no on-the-day upsells and no subcontracted fitters. Finance is available from 0% APR on eligible orders (subject to status), which spreads the cost without adding interest.
For an accurate figure on your own property, request a free no-obligation quote and we'll confirm the exact specification, glass performance and installation window before you commit.