Glossary of Terms

Modular unit to satisfy the complete hot and cool water and electrical requirements for an apartment, gas or electrical heating.

A generic term applying to factory preassembled products (usually building services) that would otherwise be assembled onsite. A typical example is a hand basin fitted with taps and waste.

Part of a building or structure that could be considered for standardisation and offsite production such as foundations, structural frame, envelope, services, internals and modular units.

The external walls and roof that form the perimeter or enclosure of a building. Walling may include lightweight curtain walling, in aluminium, steel or glass, or heavyweight components in concrete, brick or stone.

Roofing includes flat or pitched roofs. The extent of offsite manufacture will vary between systems, e.g. for curtain walls:

• stick system - components all assembled onsite
• unitised - components preassembled offsite into storey height, ~1 m wide panels
• panelised - components preassembled offsite into storey height, bay-width panels.

Applies to pre-cast concrete elements of a structure. This includes wall and floor elements, ceilings, staircases, columns and beams. Also, FEC elements can include building service containment routes, window and door openings and possibly thermal insulation.

A factory facility set up near to the construction site, usually to reduce the need for long-distance transportation of preassembled products. Particularly relevant for large scale, often civil engineering or infrastructure projects such as airports or bridges.

A factory-manufactured panel comprising a series of floor joists joined together with trimmers or end-joists to form a load-bearing element of floor construction. Generally used for residential or low to medium-rise buildings and usually steel or timber.

Pre-cast concrete systems can be used to construct foundations rapidly. The elements are usually to a bespoke design and cast in a factory environment.

These systems improve productivity, especially in adverse weather conditions, and reduce the amount of excavation required - particularly advantageous when dealing with contaminated ground.

Offsite foundation techniques also include steel mini piles and helical screw piles.

The term "Frame" typically refers to the structure of a building and may be constructed from many different materials. Also, the term may be used to describe the supporting structure for a pod or other volumetric unit.

This section includes descriptions for several terms related to frames and framing.

Currently rarely used in technique comprising panels of lightweight concrete blocks with glued joints fabricated offsite and crane lifted into position onsite.

Attractive with design appeal, glulam beams provide large-span structures without supporting columns, with lots of natural light. Glulam is a strong and sustainable alternative to concrete or steel beams. Made from layers of parallel timber laminates glued together, glulam sections are now frequently used in the construction of all types of building including supermarkets and swimming pools.

Volumetric services preassembly for vertical risers or horizontal distribution. They may contain pipework, ductwork and electrical elements.

Pre-stressed, pre-cast concrete slab unites that derive their name from the voids or cores which run through the units. The cores can function as service ducts and significantly reduce the self-weight of the slabs, maximising structural efficiency. Units are generally available in standard 1200mm widths and in depths from 110mm to 400mm.

Used in the form of beams, channels, angles and plate, the elements are fabricated in the factory with attachments and connections for ease of site erection. Also, offsite processes provide facilities for services and add fire protection.

A term describing something that is a combination of more than one discrete system or material. This term, in the context of offsite should not be confused with its use to describe the combination of structural steel and concrete in the frame of a building or structure.

Wash hand basins, urinals, lavatories assembled offsite into the “units” with a range of blackboards, taps etc. Most units are designed to be removed and replaced with new unites once they have reached the end of their serviceable life. 

A volumetric building, with steel legs that can be adjusted to suit uneven ground. Lifted into place by crane, the cabins can be stacked on top of each other and are typically used for temporary site accommodation.  See also Portable Buildings

Containment for lifts and sometimes also bracing for structural frames. They are manufactured offsite, and often in pre-cast concrete or steel.

Light gauge steel frame is a fundamentally important material to offsite construction. Structural panels assembled from cold-formed galvanised steel sections can be used in a wide range of building types and in hybrid situations with timber and other materials. Light gauge steel framing can be used for a building’s full frame but also for a variety of roofing, modular options and infill walling applications.

Light steel framing is typically used for the primary structure of housing and low-to-medium-rise buildings of two to four storeys. For taller buildings, it can be complemented by the use of hot-rolled members at key locations.