Leaded windows — also called leaded lights — are a defining feature of period properties across the UK, from Edwardian bay windows to 1930s suburban semis and Arts and Crafts cottages. Repairing them costs more than fixing a standard pane of glass, but with the right specialist, leaded lights can last another century.
For a cracked pane, expect £60–£200 including glass and re-leading. For a badly bowed or failing full window that needs complete re-leading, budget £500–£2,500, depending on size and complexity.
What Can Go Wrong with Leaded Windows
| Problem | Typical Cause | Repair Needed |
|---|---|---|
| Cracked or broken pane | Impact, thermal stress | Glass replacement + spot re-leading |
| Bowing or bulging | Lead fatigue, loss of support bars | Re-leading; add saddle bars |
| Loose or rattling glass | Dried-out cement, failed lead | Re-cementing or re-leading |
| Corroded or crumbling lead came | Age (70–120+ years), acidic environment | Full or partial re-leading |
| Draughts around frame | Lead shrinkage, failed putty | Re-cementing, brush-in compound |
| Missing or cracked decorative glass | Breakage or wartime damage | Specialist glass cut-to-pattern |
Cost Breakdown by Repair Type
Individual Pane Replacement
Replacing a single cracked or broken pane in a leaded light requires:
- Carefully folding back the lead came on two or three sides without cracking adjacent glass
- Cutting new glass to match the original profile
- Fitting and re-leading
- Re-cementing
Cost: £60–£200 per pane, depending on glass type (clear, textured, antique cylinder glass, coloured glass) and ease of access.
Antique cylinder glass (hand-blown, with characteristic imperfections) costs £30–£80 per small pane cut to shape. Obscure or art glass may require sourcing from specialist suppliers and can cost more.
Re-Cementing (Re-Pointing)
When the panel is otherwise sound but glass is rattling in old dried cement, a glazier can work lathering compound or putty under the lead flanges without removing the glass. This buys another 15–25 years before full re-leading.
Cost: £80–£200 for a typical window panel, depending on size and number of panes.
Partial Re-Leading
A section of the panel — typically a corner or area around a crack — is re-leaded without removing the whole window.
Cost: £150–£500, depending on the area affected and the complexity of the pattern.
Full Re-Leading
The entire panel is taken out, the old lead came stripped away, the glass pieces washed and checked (cracks may only become visible when backlit), then the window is re-made using new lead came. This is skilled work taking a full day or more per panel.
| Window Size | Approximate Cost (full re-leading) |
|---|---|
| Small fanlight or porthole (0.1–0.2 m²) | £150–£400 |
| Standard casement panel (0.3–0.6 m²) | £350–£900 |
| Bay window light (0.6–1 m²) | £600–£1,500 |
| Large Victorian window (1–2 m²) | £1,200–£2,500 |
| Complex stained glass panel | £2,000–£5,000+ |
Saddle Bars
Lead is soft and creeps under its own weight over decades. External horizontal steel or copper support bars (saddle bars), soldered to the lead at intervals, are the traditional solution. Adding saddle bars to a panel that lacks them: £80–£200 per window, depending on the number of bars needed.
Lead Came: H vs U Profile
Lead came comes in two profiles:
- H-came holds two panes together (used for internal joins)
- U-came (border came) runs around the perimeter
Standard lead came widths are 3 mm, 4.5 mm, 6 mm, and 9 mm face width. Matching the original width is important in conservation work. Hand-milled lead is softer and more traditional; extruded lead is cheaper and more consistent.
Conservation Areas and Listed Buildings
If your property is in a conservation area or is listed, there are important constraints:
- Listed buildings: Any repair to windows requires Listed Building Consent if the work constitutes “alteration” — though like-for-like repair using matching materials is generally exempt. Contact your local planning authority before specifying replacement glass types or lead profiles that differ from the original.
- Conservation areas: Permitted development rights are restricted. Replacing leaded lights with double-glazed units is almost always refused; repair is the expected approach.
Always check before undertaking significant window work on a listed or conservation area property.
Finding a Leaded Light Specialist
Leaded window repair is a specialist trade — not every glazier has the skills or equipment. Look for:
- Members of the Guild of Master Craftsmen or The Glaziers’ Trust
- Glaziers who specifically advertise leaded light restoration or conservation glazing
- Ask for examples of previous conservation work and references from comparable historic properties
For listed building work, a glazier familiar with local authority requirements is invaluable. Get at least two quotes, and ask each contractor to specify whether they use milled or extruded lead, the came size, and the type of cement or compound.
Is It Worth Repairing vs Replacing?
Leaded windows are heritage assets and are almost always worth repairing rather than replacing with double glazing, for three reasons:
- Planning/Listed Building constraints often prohibit replacement anyway
- Secondary glazing (an internal fixed or sliding second pane) achieves near-modern thermal performance while preserving the original window
- Value: original leaded lights in good condition add to the character and value of period properties
Well-maintained leaded lights last 80–100 years between full re-leads. The investment in specialist repair is long-term.
