Glossary of Terms

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MEP services include a number of ‘plug and play’ technologies pre-installed at the factory for plant-rooms, with pipework, cable management and ductwork for building services in-situ. These are integrated in a multi-services module mounted in the ceiling, under the floor or in service risers. Mechanical ducting or pipework systems/modules are often combined with electrical service distribution. These units are packaged or skid-mounted as pre-assembled units, pre-finished in the factory for straightforward mains connection onsite.

Systems: MEP     Components: Flooring, Roofing


These terms would imply a level of modular coordination. However, more commonly, they refer to volumetric building modules where the units form the structure of the building as well as enclosing useable space. The terms are also sometimes used to describe room modules, which do not incorporate their own superstructure. They are particularly popular for hotels and student residences due to the economies of scale available from many similar sized modules and the benefit of reduced site construction time.

Systems: Volumetric Modular

Multi-Purpose Riser

Multiple service vertical distribution module, constructed from primed or galvanised mild steel and incorporating appropriate building services which may or may not be lagged (insulated). These modules can be connected offsite, but are often transported in 7.5m lengths to avoid transportation problems. Modules can carry combined mechanical and electrical services but most manufacturers specialised in one or the other. The majority of the electrical risers are manufactured using a mesh or ladder system to allow easy distribution at floor levels in various directions. These systems are often bespoke in design and while the base structure may offer a level of standardisation the dimensions are carrying capacity will vary between projects.

Components: Insulation

Offsite Construction

Largely interchangeable terms referring to the part of the construction process that is carried out away from the building site. This can be in factory or sometimes in specially created temporary production facilities close to the construction site (or field factories). 

Systems: CLT/Glulam, Glulam, Hybrid, Light Steel Frame, MEP, Pods, Precast Concrete, SIPS, Timber Frame, Volumetric Modular

Open (Cell) Panel Timber Frame

See Frame

Systems: Timber Frame

Packaged Plant

A generic term describing on or more items of mechanical and/or electrical plant that are combined (packaged) in the factory to form a transportable unit.

See also Plant Room Module (preassembled)

Components: Machinery


A generic term describing a planar unit, typically manufactured offsite, which may or may not have a structural as well as have an enclosure function.

Related terms: Panel Building System, Pre-cast Flat Panel System, Advanced Panel Timber Frame, Structurally Insulated Panels (SIPs)

Systems: SIPS, Timber Frame

Plant Room Module (preassembled)

Packaged or skid-mounted preassembled plant rooms prefinished in the factory, ready for direct connection to mains services onsite. Can include complete plant room areas including AHU’s, fans, chillers, boilers, pumps and pressurisation units, together with elements of the building envelope.

Systems: SIPS     Components: Machinery


Pods are substantial building elements that form a volumetric space but are generally non-loadbearing. Pods can be bathrooms, shower rooms, kitchens, utility cupboards and office washrooms. They are usually craned into a building during super-structure erection, but can also be retrospectively installed via external cladding apertures and lift shafts or delivered as flat-pack assemblies.

Systems: Pods     Components: Cladding Solutions

Portable Buildings and Portable Accommodation

These are volumetric prefabricated buildings that are designed so that they can be moved and relocated. They are semi-permanent and have a relatively short life span of 20 to 30 years. Many are rented out. See also Jack-Leg Buildings.

Systems: Volumetric Modular

Prefabrication and Prefabricated Building

This is a general term for the manufacture of entire buildings or parts of buildings offsite prior to their assembly onsite. Prefabricated buildings include both portable buildings and various types of permanent building systems. Offsite is now the more commonly used term for permanent buildings procured in this manner.

Systems: CLT/Glulam, Glulam, Hybrid, Light Steel Frame, MEP, Pods, Precast Concrete, SIPS, Timber Frame, Volumetric Modular

Risers (preassembled)

Preassembled electrical and/or mechanical vertical distribution modules designed either to be self-standing structures or fixed to walls. See also Multi-Purpose Riser.

Components: Fixings & Fastenings

Roof Cassettes

A factory-manufactured panel similar to floor cassettes. For pitched roofs in residential applications they will usually be timber or steel-based SIPs spanning from eaves to ridge. They are supplied insulated and require no additional truss style support making them ideal for providing extra roof space in housing applications. They are also used in commercial situations.

Systems: SIPS, Timber Frame     Components: Roofing

Steel Panelised System

See Panel

Systems: Light Steel Frame

Structurally Insulated Panels (SIPs)

SIPS are primarily a timber-based panel that consists of two parallel faces – usually oriented strand board (OSB) or cement-bonded particleboard – with a rigid core of polyurethane (PU) foam or expanded polystyrene (EPS) inside, SIPS are a cost-effective and energy-efficient solution to a wide range of building types and can provide airtight walls and roofs. SIPS panels also offer high levels of insulation due to the use of the in-filled material. Properly used, SIPS need no other structural frame supporting them.

Systems: SIPS     Components: Building Boards

Thin Joint Masonry (preassembled)

The use of thin joint “glued” blockwork preassembled offsite into panels that are then delivered to site and installed by crane in one operation. Panels may be single skin or cavity construction complete with insulation.

Systems: Precast Concrete     Components: Insulation

Timber Frame

Timber frame building can consist of wall panels, alongside floor and roof panels – often referred to as cassettes. These can also be open panel or closed panel. Open panels are timber frame wall panels, comprising studs, rails and sheathing on one face and a breather membrane. Closed panels also include linings on the faces of the panel, a vapour barrier and breather membrane. Closed panels may also include fitted windows, openings for doors and service routes. Manufactured in factory conditions, these cassettes and panels are brought to site and fixed together to form a rigid load-bearing superstructure. These consist of timber studs and beams, stiffened on one side with oriented strand board (OSB) and plasterboard.

Systems: Timber Frame     Components: Building Boards

Timber Frame Building Systems

See Frame.

Systems: Timber Frame

Valve Assemblies (preassembled)

Valve assemblies prefabricated to individual specification, which reduce onsite installation time, site storage requirements and purchase orders.

Components: Component Suppliers

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