Original sash windows are one of the most beautiful features of period properties - but they’re also one of the most complex to maintain. This guide helps you decide whether restoration or full replacement is the right choice for your home.
Signs Your Sash Windows Need Attention
Before deciding on restoration or replacement, it’s important to understand the severity of any issues. Common signs include:
- Draughts around the sashes or frame
- Condensation forming between panes (failed sealed unit)
- Wood rot or paint failure around cills or stiles
- Sashes that stick, jam, or rattle
- Broken sash cords making the window difficult to operate
- Single glazing that significantly increases heat loss
Not all of these indicate that replacement is necessary - many can be addressed through skilled restoration.
Restoration: When It Makes Sense
Restoration is the right choice when the original window frames are structurally sound - with no widespread rot, no significant timber loss, and original profiles worth preserving.
Restoration works best when:
- Listed building or conservation area constraints apply
- The original timber is high-quality hardwood still in good structural shape
- Only cords, weights, or glazing have failed - not the frame itself
- Budget is constrained and the windows are functionally sound
Replacement: When It’s the Better Choice
Replacement becomes the better option when restoration costs approach or exceed the cost of a new bespoke unit - or when performance requirements cannot be met through repair alone.
Modern bespoke timber sash windows can be manufactured to match original profiles exactly, including slim 18mm glazing bars. With A-rated double glazing, they deliver dramatically better thermal and acoustic performance than any restored single-glazed window.
Cost Comparison
- Basic sash cord repair - £150–£300 per window
- Re-glazing (double units) - £250–£450 per window
- Full restoration (rot, glazing, decoration) - £600–£1,200 per window
- New bespoke softwood sash window - £895–£1,400 per window
- New bespoke hardwood sash window - £1,200–£2,000 per window
All prices are indicative guide prices including installation. VAT applies. Contact us for a site-specific quote.
Our Recommendation
The answer depends entirely on the condition of your current windows and your priorities around performance, heritage, and budget.
Restore if the frames are structurally sound, you’re in a conservation area, and the budget is tight. Replace if widespread rot is present, you want A-rated double glazing, or restoration costs are within 70% of replacement.
