Glossary of Terms

For project advice and support please contact our Architectural Services Team.

Curtain Wall

Air seal
The internal gasket and curtain walling grid must be sealed to stop air and therefore water passing through the system from the outside

Curtain Walling
Aluminium grid incorporating glass and panels of various materials that overclads the building structure and hangs like a curtain

The weight of aluminium and glass that the mullion has to support

Design windload
The pressure of wind acting upon the façade given in Newtons/m2. Can be positive or negative

The sums of half the width of each panel either side of a mullion, not mullion centres

Vertical bar that must withstand deadload and windload (does not support roofs) which is transferred back to the structure via brackets

Mullion drainage
Each panel within a curtain wall system is drained along the transom and down the mullion

Face cap
Aesthetic cover cap that fits over the pressure plate

Infiltration plug
Shaped EPDM plug that closes off the gap between mullions and transoms

Pressure equalisation
The principle of making a curtain wall system or window weathertight

Pressure plate
Plate that screws to the nose of the mullion and transom to retain the glass or panel

Horizontal glazing bars within a slope glazed system

Structural bar within a slope glazed system

Allows air into the glazing cavity whilst keeping out as much water as possible

Simply supported
Mullion fixed at one end taking deadload and windload with a sliding fixing at the other taking windload only. Normally storey height bars

Length of a mullion or transom between fixing points

Structural silicone glazing
Method of retaining glass by bonding the panel to an aluminium frame rather than using mechanical methods of retention i.e. pressure plates

Tandem span
Mullion spanning two storeys. Fixed at one end with a sliding fixing at the other and a sliding fixing at a point in between taking windload only

Horizontal bar that must withstand deadload and windload (does not support roofs) which is transferred back to the structure via connections to the mullions

Zone drainage
Each panel within a curtain wall system is individually drained at the end of each transom


Controlled oxidisation of the aluminium with the introduction of cobalt if bronze or black colours are required

Bottom hung
Opens in at the head, hinged at the sill

Flat chevron inserted into the corners

Open out vent either top hung or side hung, fixed light or a combination

Aluminium angle inserted at mitred corners of windows

Large outer frame divided into smaller panels with muntins. Can incorporate combinations of vents/fixed lights

Coupling mullion
Vertical bar joining two outer frames together

Couping transom
Horizontal bar joining two outer frames together

Espagnolette bolt
Multi-point locking rod for top hung or side hung vents

Fill and debridge
Resin thermal break poured into an extrusion, then part of the extrusion is removed leaving the internal and external aluminium separated by the resin

Folding opener
Holds a top hung vent at the cill when hung on hinges

Friction stays
Mechanism which holds the vent in the open position

Horizontal & vertical sliders
Panels sliding within the outer frame

Horizontal pivot
Vent frame pivots about its horizontal central axis i.e. the bottom pushes out whilst the top comes into the building

“I” Value
One of the strength properties within an extrusion

Fixing straps securing the outer frame to the structure

A bar that divides outer frames into smaller panels. Can be used horizontally or vertically

Muntin clips
Bracket that fixes muntins to outer frame

Polyamide thermal break
Glass reinforced nylon separating two aluminium extrusions

Polyester powder
Applied to pre-treated aluminium in powder form and then fused to the aluminium in an oven. Over 130 standard colours available

Side hung either open-in or open-out
Outer fixed frame with additional opening frame either hung on hinges down each jamb – open in or out – or friction stays at head and cill – open out only

Thermal break
Separates internal and external aluminium improving the thermal performance

Vent frame tilts in at the head for ventilation or swings in for cleaning (side hung)

Toe and heel
Method of glazing side hung windows and doors by transferring the weight of glass back to the hinge side

Top hung
Outer fixed frame with additional opening frame either hung on hinges at the head of the window or friction stays down each jamb

Top swing
Opens as a top hung but special gear allows the vent to swing through 180 degrees for cleaning

Turn lock handle
Allows a tilturn window to tilt for ventilation but locks out the side hung mode for safety cleaning

Vertical pivot
Vent frame pivots about its vertical axis i.e. one side pushes out whilst the other comes into the building


190/350 Doors
Kawneer fabricated, double or single acting doors for heavy and severe traffic use

Aluminium extrusion with a gasket inserted retaining the glass or panel

Bottom rail
Bottom horizontal rail on a door leaf

Bottom rail weathering
Neoprene wiping seal fitted along the bottom rail

Butt hinges
Can be used with or without exposed closer (may be left as a free swing leaf)

Concealed centre pivots
Used on free swing doors. No closer mechanism

Double action swing door
Opens both ways

Dual moment corner
Fully welded corners (4 welds per corner on 190 and 350 doors). Resists racking of door leaf

Exposed closer
Door closing mechanism face applied to door and frame at head. Single action doors only

Floor Spring
Door closing mechanism set into the floor. For use on double or single action doors

Flush bolts
Normally fitted to edge of stile at the top and bottom to retain the ‘slave’ leaf

Finger guard
For use with doors with concealed closers. Stops fingers from being trapped between door leaf and frame

Typically made of neoprene or EPDM the gaskets fit into beads and compress against the glass

Head rail
Top horizontal rail on a door leaf

Meeting stile
Central vertical members of door leaves on a pair of doors, one stile normally fitted with a lock, the other with flush bolts

Divides the door leaf horizontally into smaller panel sizes

Offset pivots
For use with exposed closer or single acting floor spring

Overhead concealed closer
Door closing mechanism concealed in frame above door leaf (door transom). For use on double action doors or double action doors made single action with a locally applied stop

Single action swing door
Opens inward or outwards, not both

Outer vertical members of a door leaf

Threshold bar
Aluminium plate fitted to floor beneath door leaf

Tie rods
Bars that are fitted to stiles and run through head and bottom rails to provide strength and stop the leaf from racking


451PT Framing System
Simple extruded aluminium glazing system suitable for ground floor application

Door jamb
Vertical framing member at the side of a door

Door transom
Framing bar directly over a door

End dam
Closes off ends of sill flashing for weathering purposes

Expansion mullion
Male and female two part mullion allowing horizontal movement

Vertical framing bar

Screw spline construction
Method of connecting two components using screws into specially extruded grooves

Shear block construction
Method of fabrication fixing shear blocks (brackets) to the mullion, then the transoms to the shear blocks

Shuffle glazing
Method of glazing by moving the glass one way and then the other into the glazing pockets

Cill flashing
Aluminium extrusion onto which the framing sits

Horizontal framing bar

Transom plate
Flat cover plate on underside of door transom enclosing concealed closer