Cracked Window Glass in Dulwich: Keeping the Original Timber Window

Replacing one pane. Keeping the original timber window.

A cracked pane can make an otherwise usable window look like a much bigger problem. At this Dulwich property, our job was specific: replace one damaged bedroom pane while retaining the existing timber window.

Completed on 23 October 2026, the repair included removing the damaged glass, preparing the glazing rebate, fitting a new clear pane and renewing the glazing seal. These photographs follow the work from the original crack to the finished result.

Completed timber sash window after replacement of one cracked pane in Dulwich — The replacement pane fitted within the existing timber sash window.

One damaged pane. A focused repair.

The enquiry concerned a cracked, clear single-glazed pane in a timber bedroom window. The close-up shows the fracture running towards the bottom edge.

Cracked lower pane in the timber bedroom window before repair — Before: the crack runs through the lower pane, close to the glazing edge.

The agreed work was a glass replacement. The surrounding frame and the other panes stayed in place as part of the existing window.

That distinction matters. Glass, timber, seals and moving parts perform different jobs. A fault in one component does not automatically mean the complete window needs replacing. Traditional timber windows can often be repaired, subject to their condition. [1]

Diagram showing one replacement glass pane with the existing timber frame, sash and glazing bars retained — One replacement pane, with the existing timber frame, sash and glazing bars retained. Simplified illustration.

Care at the glazing edge

The quality of a glass repair depends on the preparation around the pane as well as the glass itself.

Lower timber sash removed from the opening for access to the glazing — During: the lower sash removed from the opening for access to the glazing.

Timber sash supported horizontally during glass replacement — During: the sash supported horizontally while the pane and its edges are worked on.

Remove the damaged pane. The cracked glass was removed from the existing timber sash.
Prepare the rebate. The recessed timber edge that receives the glass was prepared for the replacement.
Fit and seal. One new clear pane was fitted and the glazing seal renewed around its edges.
Finish and clear away. The sash was returned to the window and broken glass and waste from the work removed.

Glass, measuring equipment and glazing materials on site — Work in progress: glass, measuring equipment and glazing materials on site.

The original window stays

The cracked pane was replaced and the existing timber window retained. The familiar glazing-bar layout and overall appearance remained.

Repaired lower sash raised in the existing timber frame — After fitting: the lower sash is shown raised in the existing frame.

The finished photographs show the window both closed and with its lower sash raised. The completed works report recorded the glass replacement, with before, during and after photographs supplied alongside the invoice.

This was a targeted glazing repair. It did not include a full timber refurbishment or repainting; the surrounding decorative finish remains a separate maintenance item.

Similar symptoms can need different repairs

Diagram comparing cracked glass, damaged timber and sticking sash repairs — Different window faults need different repairs: cracked glass, damaged timber and a sticking sash.

Cracked glass: assess the pane and glazing edge. A glass-only repair may be suitable.
Damaged timber: assess the frame or sash. Glass replacement alone will not repair decayed wood.
Sticking sash: check the moving parts and fit. Sound glass may be retained.

A small repair, properly assessed

Does a cracked pane mean I need a new window?

Not necessarily. This job was completed by replacing one pane and retaining the timber window. The decision depends on the condition of the sash, frame and glazing edges, and on what else needs attention.

Can the same glass be fitted in every window?

No. The specification depends on the pane's size, position and use. Glazing in vulnerable locations may need safety glass. A photograph alone does not establish the right specification, so the location needs to be assessed. [2]

Will glass replacement also deal with paintwork or rot?

Those are separate issues. This repair included preparing the glazing rebate and renewing the seal around the replacement pane. Wider timber repairs and redecoration were outside the agreed scope. Keeping the timber finish and glazing edges maintained helps protect the window. [3]

What should I send when asking about a repair?

A clear photograph of the whole window, a closer view of the damage taken from a safe position, your postcode and any access details are useful. Mention whether the window opens normally. Avoid pressing on cracked glass or forcing the sash.

Need help with damaged window glass?

Royal Security repairs doors, windows and locks across London and Essex. Send a few photographs and tell us what has happened so we can advise on the next step.

Contact Royal Security about a window repair.