Office partitioning glossary

A

Acoustic insulation

Mineral wool or similar material placed in the cavity of a stud or demountable partition to absorb sound and improve its Rw rating. It performs well with dense board linings and well sealed perimeters, and may also contribute to fire performance in tested systems. Related: Acoustic Partition Walls

Acoustic laminate

Laminated glass made with a special sound-damping interlayer. A 12.8mm acoustic laminate typically achieves around 38–40 dB Rw in laboratory tests, compared with about 32–35 dB for 10mm toughened glass, while also holding together if broken. Related: Acoustic Glass Partitions

Approved Document B

The statutory guidance supporting Part B (fire safety) of the Building Regulations in England. For partitions it covers means of escape, travel distances, inner rooms, fire resisting construction, compartmentation and fire doors. Related: Fire Rated Glass Partitions

Approved Document K

The statutory guidance supporting Part K (protection from falling, collision and impact) in England. Section 7 covers safety glazing in critical locations and manifestation on glazing in zones 850–1000mm and 1400–1600mm above floor level. Related: Glass Manifestation & Privacy Film

Approved Document M

The statutory guidance supporting Part M (access to and use of buildings) in England. For partitions it influences door clear widths, opening forces, vision panels, visual contrast and the position of door ironmongery. Related: Office Glass Doors

B

BS EN 12600

The European standard for the pendulum impact test used to classify flat glass by how it behaves when struck. Safety glass in partitions and doors is classified under this standard, for example class 1B1 or 1C1, to show it breaks safely. Related: Glass Office Partitions

BS EN 1364-1

The standard for fire resistance testing of non-loadbearing walls, including glazed and stud partitions. A full-size specimen is exposed to a furnace and results are classified, for example as EI 30 or EI 60, under BS EN 13501-2. Related: Fire Rated Partition Walls

BS EN 1634-1

The standard for fire resistance testing of doors, shutters and openable windows. Fire doors within partitions must be part of an assembly tested or assessed to this standard, including the leaf, frame, glass, seals and ironmongery. Related: Office Glass Doors

Building Control

The process of checking that building work complies with the Building Regulations, carried out by the local authority or a registered Building Control approver. Partitions that affect escape routes, fire separation or access usually need an application.

Bulkhead

A section of wall or boxing built down from the ceiling or soffit to meet the top of a partition, conceal services or step between ceiling levels. Bulkheads are often formed in metal stud and plasterboard above glazed screens. Related: Metal Stud Partition Walls

Butt-joint

A joint where two panes of glass meet edge to edge without a vertical frame, sealed with a thin bead of clear silicone. Butt-joints give frameless glass partitions their continuous, minimal appearance. Related: Frameless Glass Partitions

C

Cat A

Category A fit-out: the landlord's base build that makes office space lettable, typically including raised floors, suspended ceilings, base lighting, heating, ventilation, cooling, fire alarm and finished toilets, delivered as open plan.

Cat B

Category B fit-out: the occupier's own fit-out of a Cat A space, including partitions, meeting rooms, kitchens, furniture, AV, branding and the services alterations needed to suit the new layout. It is usually paid for by the tenant. Related: Meeting Rooms & Glass Pods

CDM 2015

The Construction (Design and Management) Regulations 2015, which apply to all construction work in Great Britain, including commercial fit-out and partitioning. They set duties for clients, designers and contractors to plan and manage health and safety.

Ceiling void barrier

A barrier installed in the void above a suspended ceiling, in line with a partition, to reduce sound or fire passing over the top. It is usually dense mineral wool or plasterboard, sealed around services and extended to the soffit. Related: Acoustic Partition Walls

Cellular office

A private, enclosed office for one or a few people, as opposed to open plan. Cellular offices are often built with glass fronts on the corridor and stud or demountable walls between rooms. Related: Private & Cellular Offices

Compartmentation

The division of a building into fire-resisting compartments by walls and floors, to contain a fire and protect escape routes. Partitions must not compromise existing compartment lines, and services passing through them need fire stopping. Related: Fire Rated Partition Walls

Critical location

An area where people are more likely to collide with glazing, such as glass in or beside doors and glass between floor and waist level. Approved Document K requires safety glass or protection in critical locations. Related: Glass Office Partitions

Crittall-style

A description of black framed glazing with slim glazing bars that recreates the look of traditional steel windows. Crittall is a trade mark of Crittall Windows Ltd; Crittall-style systems may be steel or aluminium made by other manufacturers. Related: Black Framed Glass Partitions

D

Deflection head

A head detail that allows the structure above to move or deflect without loading the partition. It typically uses a deep head track with a gap at the top of the studs or glass, sealed with materials matching the required acoustic or fire performance. Related: Metal Stud Partition Walls

Demountable partition

A modular partition system of prefinished solid or glazed panels on a steel or aluminium frame that can be taken down and rebuilt elsewhere. It installs without wet trades and suits changing layouts and shorter leases. Related: Demountable Partitions

Dilapidations

A tenant's obligations at the end of a commercial lease to repair, redecorate and reinstate the premises. They often include removing partitions installed under a licence for alterations and making good ceilings, floors and walls. Related: Partition Removal & Strip-Out

DnT,w

The weighted standardised level difference, a site-measured rating of sound insulation between two rooms. Unlike laboratory Rw, it includes flanking paths such as ceiling voids, floors and doors, so it describes real performance. Related: Acoustic Partition Walls

Door closer

A mechanical device that closes a door automatically after it is opened, controlling speed and latching. It may be overhead, concealed in the frame, built into a hinge or set into the floor as a floor spring. Fire doors need closers matching their tested configuration. Related: Office Glass Doors

Drop seal

An automatic acoustic seal fitted in the bottom of a door that lowers onto the floor as the door closes and retracts as it opens. It closes the gap under the door, an important sound path in meeting rooms. Related: Acoustic Glass Partitions

Dry-joint

A joint between frameless glass panes made with a clear or coloured plastic profile instead of wet silicone. Dry-joints are quick to install and replace, and give a consistent, neat line between panes. Related: Frameless Glass Partitions

F

Fire stopping

Sealing gaps and penetrations in fire-resisting walls and floors, such as around cables, pipes and ducts, with tested materials so fire and smoke cannot pass. The fire stopping product must be suitable for the specific penetration and construction. Related: Fire Rated Partition Walls

Flanking

Indirect sound transmission around a partition rather than through it, for example via the ceiling void, raised floor, window mullions, ductwork or door gaps. Flanking is why site sound insulation is usually several decibels below the laboratory rating. Related: Acoustic Partition Walls

Floor channel

The section fixed to the floor that holds the base of a partition, whether glass, studs or demountable panels. In frameless glass systems it is usually a slim aluminium channel with gaskets that grip and seal the glass. Related: Glass Office Partitions

Floor spring

A door closer concealed in the floor beneath a pivot door, controlling how the door swings and closes. Floor springs are common on frameless glass doors and can include hold-open and adjustable closing speed functions. Related: Office Glass Doors

G

Glazing bar

A slim bar that divides a glazed panel into smaller panes, either structurally or as an applied decorative strip. Glazing bars create the characteristic grid of Crittall-style black framed partitions. Related: Black Framed Glass Partitions

H

Head track

The section fixed to the ceiling or soffit that holds the top of a partition. In stud partitions it is a steel channel receiving the studs; in glass partitions it is usually an aluminium channel matching the floor channel. Related: Metal Stud Partition Walls

I

In-plant office

A self-contained office built inside a larger building, such as a warehouse or factory, using partition systems rather than traditional construction. It often has glazing for visibility over the operational floor. Related: Warehouse & In-Plant Offices

Insulation (EI)

In fire classification, the ability of a partition to limit the temperature rise on its unexposed face, shown by the letter I. An EI 30 partition maintains integrity and insulation for at least 30 minutes in a standard fire test. Related: Fire Rated Glass Partitions

Integral blinds

Venetian or pleated blinds sealed within the cavity of a double glazed partition, operated by a magnetic slider, cord or motor. They stay clean and protected and typically add around £150–£250 per m² of glazing. Related: Double Glazed Partitions

Integrity (E)

In fire classification, the ability of a partition to prevent flames and hot gases passing through it, shown by the letter E. An E 30 partition maintains integrity for at least 30 minutes but does not limit radiant heat. Related: Fire Rated Glass Partitions

Intumescent seal

A seal that expands when heated to close gaps around fire doors, glass and frames during a fire. Intumescent seals are an essential component of tested fire rated partitions and doors and must match the tested specification. Related: Fire Rated Glass Partitions

L

Laminated glass

Two or more panes bonded with a plastic interlayer, made to BS EN 14449 and EN ISO 12543. If broken, the pieces stay attached to the interlayer, giving safety and security benefits. Acoustic interlayers improve sound insulation. Related: Acoustic Glass Partitions

Licence for alterations

A formal document in which a landlord consents to a tenant's alterations, such as partitions. It usually attaches approved drawings, sets conditions for the work and states whether the alterations must be removed at lease end.

M

Manifestation

Visible markings on glass partitions and doors that make the glass obvious and prevent collisions. Approved Document K guidance places manifestation in two zones, 850–1000mm and 1400–1600mm above floor level, with clear contrast. Related: Glass Manifestation & Privacy Film

Means of escape

The routes people use to leave a building safely in a fire, including corridors, stairs and exits. New partitions must not reduce the safety of means of escape, and may need fire resistance where they form protected routes. Related: Fire Rated Partition Walls

Metal stud

A lightweight galvanised steel section used to frame a stud partition, fixed between a floor channel and head track and lined with plasterboard. Metal stud partitions typically cost around £55–£90 per m², excluding VAT. Related: Metal Stud Partition Walls

Mullion

A vertical member dividing a window or glazed screen. In partitioning, the term usually refers to the vertical bars of external windows, which set where internal partitions can meet the façade and can carry flanking sound.

O

Operable wall

A moveable wall of panels hung from a ceiling track that can be slid out to divide a room and stacked away to open it. Operable walls typically cost £900–£1,600 per m², excluding VAT, and usually need structural support above. Related: Folding & Sliding Partition Walls

P

Partition junction

The point where a partition meets another element, such as an external wall, window mullion, column or another partition. Junctions must be detailed carefully to maintain acoustic, fire and visual performance.

PDLC

Polymer dispersed liquid crystal, the film used in most switchable smart glass. With power applied, the crystals align and the glass is clear; without power, they scatter light and the glass turns frosted. Related: Switchable Smart Glass Partitions

Pivot door

A door that rotates on pivot pins fixed into the floor and head rather than on side hinges. Pivot doors are common in frameless glass partitions and are often controlled by a floor spring. Related: Office Glass Doors

Plasterboard

Sheet material of gypsum between paper liners, used to line stud partitions. Standard, acoustic, fire-resistant and impact-resistant boards are available, and the board type and number of layers determine much of a partition's performance. Related: Metal Stud Partition Walls

Practical completion

The stage at which the works are complete except for minor defects that do not prevent use. It usually triggers handover, the start of any defects period and release of part of the retention under the contract.

Principal contractor

Under CDM 2015, the contractor appointed by the client to plan, manage and coordinate health and safety during construction where more than one contractor is involved. The appointment should be made in writing.

Principal designer

Under CDM 2015, the designer appointed by the client to plan, manage and coordinate health and safety in the pre-construction phase where more than one contractor is involved, including gathering pre-construction information.

R

Raised access floor

A floor of removable panels on pedestals, creating a void for cables and services. Partitions may sit on top of it or pass through to the slab, and floor void barriers may be needed for acoustic or fire reasons.

RAMS

Risk assessments and method statements: documents prepared by a contractor that identify hazards in the work, the controls in place and the safe sequence for carrying it out. Landlords and clients usually request RAMS before work starts.

Rw

The weighted sound reduction index, a laboratory rating in decibels of how well a partition reduces airborne sound, measured to BS EN ISO 10140 and calculated to BS EN ISO 717-1. Higher numbers mean better sound insulation. Related: Acoustic Glass Partitions

S

Setting out

Marking the exact positions of partitions, doors and junctions on the floor and ceiling before installation, based on the approved drawings. Accurate setting out ensures that made-to-measure glass and frames fit as intended.

Sightline

The visible width of a frame, mullion or joint when looking at a glazed partition. Slim sightlines give a more minimal appearance, and frameless glass with butt-joints or dry-joints offers the slimmest sightlines. Related: Frameless Glass Partitions

Snagging

Identifying and fixing minor defects at the end of a project, such as marks on glass, misaligned doors, gaps in silicone or damaged finishes. A snagging list is usually agreed before or at practical completion. Related: Partition Repairs & Maintenance

Soffit

The underside of the structural floor or roof above, as opposed to the suspended ceiling. Partitions taken through the ceiling void to the soffit give better acoustic and fire separation than those stopping at the ceiling.

Suspended ceiling

A ceiling of tiles or boards hung on a grid below the soffit, creating a void for services. Partitions may fix to the ceiling grid or pass through it, which affects acoustic separation, fire separation and reinstatement at lease end.

T

Toughened glass

Glass heat treated to BS EN 12150 so that it is several times stronger than ordinary annealed glass and breaks into small, relatively blunt pieces. It cannot be cut or drilled after toughening, so it is made to measure. Related: Frameless Glass Partitions

Toughened safety mark

A permanent mark, usually in a corner of the pane, identifying toughened safety glass, the standard it meets, such as BS EN 12150, and often the manufacturer and impact classification to BS EN 12600. Related: Glass Office Partitions

Transom

A horizontal member dividing a glazed screen or door opening, for example above a door or between upper and lower panes. Transoms can carry manifestation, add stiffness and create space above doors for over-panels. Related: Black Framed Glass Partitions

V

Vision panel

A glazed panel in a solid door or wall that allows people to see through, improving safety on circulation routes and visibility into rooms. Approved Document M guidance covers vision panels in doors on circulation routes. Related: Office Glass Doors