Security glazing in Chalk Farm

Listed buildings and conservation areas

In England, listed building consent from the council may be needed to replace historic glass such as crown or cylinder glass, or to alter glazing bars, sashes and frames. Historic England publishes guidance on traditional windows. Secondary glazing and window film are often easier to agree because they can be removed later, but the council's conservation officer makes the decision.

Replacing glass in an existing frame

Replacing only the glass or sealed unit in an existing frame is generally treated as a repair in England rather than notifiable building work. Replacing a whole window or door is notifiable and is normally certified through a competent person scheme or approved by building control. Either way, new glass in a critical location should still be safety glass.

Safety glass in critical locations

In England, section 5 of Approved Document K treats glazing in doors and in side panels within 300 mm of a door edge, from floor level up to 1,500 mm, and any other glazing below 800 mm, as a critical location. Glass there should break safely, be robust, or be guarded. Laminated or toughened glass meeting BS EN 12600 class 3 is the usual answer, rising to class 2 for door and side-panel panes wider than 900 mm.