Sash Window Repair Cost Guides

Repair when timber rot is under 30%, sashes operate smoothly, and original features are intact. Individual repairs cost £40-£400 per window. Full refurbishment costs £600-£1,200 per window.

Repair Guides by Service Type

Common Sash Window Repairs

Sash Cord Replacement (£120-£180 per window)

Replace all 4 cords (2 per sash), adjust sash weights to balance the new cord length, test operation. Takes 2-3 hours per window. DIY cost: £15-£25 in materials (cotton sash cord, time). Most common repair. Broken cords cause sashes to drop or won't stay open.

Glass Replacement (£80-£250 per window)

Remove broken glass, measure and cut new pane, fit with putty and glazing sprigs. Float glass £80-£140 per window, crown glass (period authentic) £180-£250. Georgian bar windows add £40-£70 for the extra small panes. DIY possible if you're confident with putty work.

Draught Sealing (£140-£280 per window)

Fit brush pile or compression seals in staff bead and parting bead. Professional installation £140-£280, DIY kits £30-£60 per window. Saves £60-£120 per year in heating per window. Payback period 1.8-4.7 years. See our draught proofing calculator.

Strip and Repaint (£200-£400 per window)

Remove old paint with heat gun or chemical stripper, sand smooth, fill defects, prime bare timber, apply undercoat and 2 gloss coats. Takes 1-2 days per window including drying time. DIY cost: £40-£80 in materials, 8-12 hours labour. Essential every 5-8 years to prevent timber rot.

Sill Repair (£150-£350 per window)

Cut out rotten timber, splice in new hardwood section, epoxy fill small voids, sand and paint to match. Minor repairs (under 30% of sill) £150-£220, major repairs or full sill replacement £250-£400. Uses hardwood (iroko, sapele, oak) to match durability of original. Most common area for timber rot.

When to Repair vs Replace

Repair your sash windows when:

• Timber rot affects less than 30% of the frame (repairable with splicing)
• The sashes operate smoothly and are square in the frame
• You're in a conservation area or listed building (like-for-like repair required)
• Total repair cost is under 60% of replacement cost (under £540-£840 in repairs)
• Original features are intact and add character (glazing bars, shutters, period glass)

Consider replacement when:

• Timber rot exceeds 30% (multiple sill, rail, and stile repairs needed)
• The box frame is rotten (very expensive to repair, £800-£1,500 per window)
• You want double glazing (slim DG retrofit £800-£1,600 or full DG replacement £900-£2,200)
• Total repairs exceed £800-£1,000 per window (cheaper to replace with new timber at £900-£1,400)

See our refurbishment cost guide for the full repair vs replace decision framework.