Sash Window Replacement Cost Guides
Replace when timber rot exceeds 40%, box frames are collapsed, or you want modern thermal performance. Replacement costs £600-£2,200 per window depending on material, glazing, and period detailing.
Replacement Guides by Material and Style
UPVC Sash Windows Cost
UPVC vs timber comparison, woodgrain finishes, A+ energy rating. £600-£1,200 per window.
Double Glazed Sash Windows Cost
Slim double glazing retrofit vs new replacement, U-values, conservation area approval. £800-£1,600.
Wooden Sash Windows Cost
Timber species (sapele, accoya, iroko), engineered vs solid, lifespan. £900-£1,800 per window.
Georgian Sash Windows Cost
6-over-6 glazing bars, slimmer frames, crown glass, period-correct hardware. £1,200-£2,400.
Victorian Sash Windows Cost
2-over-2 standard, horned sashes, stained glass inserts, bay window pricing. £900-£2,200.
Replacement Cost Calculator
Interactive calculator: input window count, material, size, and glazing options. Get instant quote.
Replacement vs Repair Decision
Replace your sash windows when:
- Timber rot exceeds 40% of frame volume (uneconomical to repair)
- Box frame is rotten or collapsed (repair costs £800-£1,500 per window)
- You want modern thermal performance (U-value under 1.8 W/m²K, repair achieves 2.4-3.2)
- Total repair cost exceeds 75% of replacement cost
- Property is not listed and you plan to sell within 10 years
Consider repair instead when:
- Listed building or conservation area front elevation (like-for-like required)
- Original features intact (glazing bars, shutters, weights, pulleys)
- Timber rot under 30% (splice repairs cost £150-£350 per sill/rail)
- Property value exceeds £800k (period features add 5-8% premium)
See our refurbishment cost guide for the full repair vs replace decision framework.
Related Guides
- Repair Cost Guides — cord replacement, draught seals, sill repairs
- Energy Efficiency Guides — draught proofing, double glazing costs
- Refurbishment Cost Guide — repair vs replace decision