Glossary of glazing terms
The words you will hear at survey, explained in plain English.
- Glazing bar
- A slim bar that divides a sheet of glass into smaller panes, either running through the glass or fixed to its faces. Also called an astragal bar.
- Sightline
- The visible width of a frame or bar when you look at the screen face-on. Slimmer sightlines mean more glass and less metal.
- Transom
- A horizontal bar or frame member, often at door-head height, dividing the screen into an upper and lower section.
- Mullion
- A vertical frame member dividing a screen or window into separate lights.
- Toplight
- A fixed glazed panel above a door or screen, often used to fill the space up to a high ceiling.
- Sidelight
- A fixed glazed panel beside a door, within the same frame.
- Powder coating
- A durable paint finish applied as a dry powder and baked on. It gives steel and aluminium frames their colour and protection.
- RAL colour
- A standard European colour reference system used to specify frame colours, such as RAL 9005 for jet black.
- Toughened glass
- Glass heat-treated to be several times stronger than ordinary glass, breaking into small blunt pieces if it fails.
- Laminated glass
- Two or more layers of glass bonded with a plastic interlayer that holds the pane together if broken.
- Acoustic glass
- Laminated glass with a sound-damping interlayer that reduces noise passing through.
- Reeded glass
- Glass with fine parallel ribs pressed into one face, giving privacy while letting light through.
- Thermally broken
- A frame with an insulating barrier between its inner and outer parts, reducing heat loss in external doors and windows.
- Pivot door
- A door that rotates on pivots set into the floor and head of the frame rather than hanging on side hinges.
- French doors
- A pair of hinged glazed doors that meet in the middle without a central post.
- Fire-rated glazing
- Glass and frames tested together to resist fire for a set time, used on escape routes.
- Protected escape route
- A stairway or corridor enclosed by fire-resisting construction so occupants can leave safely in a fire.
- Safety glazing
- Glass that meets impact standards such as BS EN 12600, required in critical locations by Approved Document K.
- Approved Document K
- The part of the Building Regulations guidance in England covering protection from falling, collision and impact, including safety glazing.
- Scribing
- Shaping the edge of a frame to follow an uneven wall, floor or ceiling for a tight fit.
- Manifestation
- Marks or patterns applied to large areas of glass so people can see it, required in many commercial buildings.
- Steel-look aluminium
- Aluminium profiles shaped and finished to look like slim steel frames, at a lower cost and weight.