Single vs Double Glazing Repairs: How the Work Differs

Single glazing is one pane of glass held in the frame with putty or beads, so a broken pane can often be cut and fitted quickly. Double glazing uses a factory sealed unit that is made to measure, so repairs usually involve measuring first and fitting later. Both are fully repairable, and the right fix depends on the frame, the position of the window and what you want from it.

How each type is built

Single glazing is a single sheet of glass, typically in timber sash or casement windows, older steel frames, internal doors and some outbuildings. It is held by linseed putty on older timber frames or by timber or metal beads on others.

Double glazing is two panes separated by a spacer bar and sealed around the edge, forming one unit. The space between is filled with dry air or gas. The unit sits in the frame on packers and is held by beads, usually from the inside on modern uPVC windows.

Repairing single glazing

A broken single pane is removed piece by piece, old putty or beads are cleared, and a new pane is cut to size and bedded in. Plain float glass can often be cut from stock, though doors and low panes may need toughened or laminated glass by law. On putty glazed timber, the new putty needs time to skin over before painting.

Other single glazing repairs include reputtying loose panes, replacing sash cords and easing sticking sashes.

Repairing double glazing

Most double glazing repairs are either a new sealed unit or new hardware. Misting between the panes, cracks and failed seals all mean a new unit, made to the exact size and glass specification. Hinges, handles, locks and gaskets are separate parts that can be changed on their own.

Side by side

The table below sets out the practical differences you are likely to notice when booking a repair.

• Glass: single uses one pane, double uses a sealed unit
• Stock glass: single plain panes can often be cut on the day, sealed units are made to measure
• Fixing: putty or beads for single, beads for double
• Common faults: broken panes and loose putty for single, misting and hardware for double
• Safety glass: required in doors and low positions for both types

Should single glazing be upgraded?

Not always. In period timber windows, repairing the original single glazing keeps the character and is often the simplest route, and draught proofing can make a real difference. In other frames, a slim sealed unit may be possible where the rebate is deep enough. It is worth asking at the quoting stage, and our guide to repairing or replacing windows covers the wider decision.

Costs in general terms

No new prices are quoted here, but the general pattern is widely known across the trade. A plain single pane is usually the least expensive glass to replace, because it is one sheet cut to size. A sealed unit costs more, as it is two panes, a spacer and a seal made up in a factory. Safety glass adds to either, and specialist glass such as acoustic, low emissivity or patterned glass adds more again.

Labour follows access rather than glass type. A ground floor casement is quicker than a first floor sash or a large patio panel, whatever the glass. The simplest way to compare is to send photos and ask for a fixed price on each option, then weigh up the difference against the benefit you want.

Call Mark on 07535 916982 or request a callback.