Windows trade jargon

Jargon by trade

A noble gas used to fill the space between sheets of glass in some double glazed windows, chosen for its insulating properties.

Bifold door

A door system - made up of three or more glass panes - which fold back fully on themselves when opening.

Conservation area

An area designated by the local authority to be of special historical or architectural significance, in which certain developments may be restricted.


A type of framed window which projects vertically though a sloping roof.

Double glazing

Window or door glazing constructed from two layers of glass, with a space in between to improve heat and sound insulation.


French windows / doors

A set of two outward-opening windows or doors.


The vertical part of a door or window frame.


Short for Pilkington K Glass, a kind of glass used to reduce heat loss due to a special coating on the inside of the glass.


A type of window made of panels which are slid vertically. Also refers to the moving panel of the window.

Self-cleaning glass

Glass which is designed to be resistant to dirt build up, using sunlight and rain water. Pilkington Activ and St Gobain Bio-clean are brand names for this type of glass.


The ledge at the bottom of a window.

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