Glossary of Terms

Awning Window

A casement window that is hinged at the top.

Bay Window

A large window, usually with three sides, that sticks out from the main wall of the building

Casement Window

A casement window is perhaps the most popular style of window in the UK and a type of window that is attached to its frame by two or more hinges. The most common casement window is hinged on either the right or left hand side and opens like a door. A casement window hinged at the top is sometimes called an awning window and a casement window hinged at the base is also called a hopper window. A tilt and turn window for instance acts as a hopper window in its ‘tilt’ position. Casement windows are fitted within a frame and are used either singularly or as a pair.

Curtain Walling

Curtain walling or curtain wall systems are typically manufactured using extruded aluminium profiles that are infilled with glass and sometimes infill panels. Curtain walling is designed to span multiple floors covering the outside of a building, typically high rise office blocks, where the outside walls are non-structural. It can therefore be constructed of lightweight material, typically extruded aluminium members, thereby reducing construction costs. The curtain wall façade does not carry any dead load weight from the building other than its own dead weight load. Where the building is subject to wind loads the curtain walling will transfer the load to the main building structure through connections to the building at the floors or the columns.

The curtain wall is designed to be aesthetically pleasing as well as allowing large amounts of natural daylight into the building. Where solar glare and thermal comfort is a problem, louvers and reflective glass can be fitted. Curtain walling can also include opening windows and vents.

Curtain wall systems must take into consideration a number of design requirements including thermal expansion and contraction, resistance to air and water infiltration, building sway due to wind loads (and in area of seismic activity, seismic forces), the building’s own dead weight load forces, thermal efficiency for cost effective heating and cooling.

Dormer Window

An upright window fitted in a sloping roof

Double Glazing

Doors and windows that have been fitted with two layers of glass which makes the building both warmer and quieter


A small window fitted above a door or window

French Doors / Windows

Two doors, made up mainly of glass that open from the centre and lead out to the garden or courtyard.

Hopper Window

A casement window hinged at the base and tilt open.

Oriel Window

A window that sticks out from wall of a building

Picture Window

A large window fitted with a large sheet of glass to provide uninterrupted views

Revolving Door

A set of doors that revolve around a central pillar

Sash Window

A window that is made from two separate pieces of glass fitted inside two frames. To open or close the window, one frame slides past the other.

Shop Front Systems (also known as Ground Floor Treatment)

These are similar to curtain walling but do not span multiple floors and are not subject to the same design requirements as curtain walling


A window in a roof or ceiling whose purpose is to allow light to stream in.

Sliding Door

A door that is opened and closed by the action of sliding.

Stable Door

A door that is made up of two halves, allowing the bottom half to be kept shut and the top half left open.

Swing Door

A door without a handle that can be pushed open from either side and automatically closes once you pass through it.

Tilt and Turn Window

A window with a double opening action. They can be tilted inwards to allow ventilation or turn fully inwards for easy cleaning.