Temporary works glossary

TERM

CATEGORY

DESCRIPTION

REFERENCE/SOURCE

Angle of repose

Geotechnical

The steepest angle to the horizontal that a heaped granular soil will stand in stated condition. The safe angle that ground conditions can be excavated without mechanical support or soil stabilisation with no risk of collapse.

CPA STIG-TIN-201, p1

Appointed person (AP)

People/Organisation

The person nominated (typically by the employing organisation) to plan and to have overall control of the lifting operations.

BS 7121-1:2016

Appointment letter

Temporary works documents

A document that formally invites an individual to accept a specific position, in which their roles and responsibilities are outlined.

BS 5975:2019, 9.3.2, 9.3.3, 9.3.4

Approval in principle

Temporary works documents

A document that outlines the concept for the design of a structure.

BS 5975:2019, 13.8.5

Note: Different item from the CG 300 Technical approval of highway structures

Audit

Management and controls

A systematic and independent examination to determine whether activities comply with the defined process and intent of the temporary works procedure.

Axial force

Technical

Any force acting directly on the centre axis of an object, such as a beam or column. May be in compression or tension.

Backpropping

Technical

Propping installed at levels below the slab that supports the falsework, in order to distribute the load on the uppermost slab to suitable supports, such as lower slabs or foundations.

BS 5975:2019 3.3

Backfill

Geotechnical

Loose material, such as rocks, soil or aggregate, used to cover over a pipe in a trench or fill an excavation.

CPA STIG-TIN-201, p2

Base plate

Technical

A rigid plate used for spreading the load in a standard, raker or other load-bearing member over a greater area.

BS 5975:2019, 3.4

Beam bearer

Technical

A structural horizontal member that resists loads applied laterally to its axis, transferring loads to vertical members, such as props and columns.

BS 5975:2019, 3.6

Blinding

Technical

A layer of lean concrete on soil to prevent local degradation and provide a clean workplace for construction work.

BS 5975:2019, 3.4

Bracing

Technical

A component placed diagonally to strengthen a framework, generally providing lateral stability.

BS 5975:2019, 3.8

British Standard

Temporary works documents

A specification of recommended procedure, quality of output, terminology, and other details, in a particular field, drawn up and published by the British Standards Institution (BSI).
British Standards are not legislation and do not have to be complied with. They might be regarded as examples of 'good practice' and can be used as evidence in court, to say that by following a British Standard you are doing everything reasonable.

BS 0:2021

Buildability

Management and controls

The extent to which the design of a building facilitates ease of construction, subject to the overall requirements for the completed building.

CIRIA (1983) Buildability: an assessment (Special Publication 26). London: Construction Industry Research and Information Association

Characteristic

Administrative/Management

A distinguishing quality of a thing.

Characteristic strength

Technical

The point at which a tested member will normally fail.

BS 5975:2019, 3.10

Checklist

Management and controls

A document that lists activities that need to be inspected and/or tested. 

BS 5975:2019, 3.11

Client

People/Organisation

The organisation or person for which/whom a construction project is carried out.

BS 5975:2019, 3.12

Cohesion

Geotechnical

A measure of the shear strength of a (cohesive) soil. Its ability to ‘remain’ or ‘stick’ together.

CPA STIG-TIN-201, p4

Cohesive soil

Geotechnical

Soil that exhibits cohesion, typically having a significant proportion of clayey materials. Bonding between the very small particles results from their lamellar shape and being densely packed, restricting the movement of air and water. Cohesive soils tend to lose their internal strength following excavation. 

CPA STIG-TIN-201, p5

Compaction

Geotechnical

The packing together of particles of soil, by rolling, ramming or vibrating, which results in a decrease in air voids and an increase in the density of the soil.

CPA STIG-TIN-201, p5

Competent organisation

People/Organisation

An organisation:
• with sufficient skills, knowledge and experience of the specific tasks to be carried out
• that can demonstrate good organisational ability in terms of its approach to the wellbeing of people affected by the work it carries out.

PAS 8811:2017, 3.4.1

Competent person

People/Organisation

Someone with the necessary skills, knowledge and experience (and organisational capability) of the specific tasks to be carried out, and the risks which the work will entail, to:
• enable them to carry out their duties in relation to the project
• recognise their limitations
• take appropriate action in order to prevent harm to those carrying out construction work, or those affected by the work.

BS 5975:2019, 3.13

Consequence of failure risk (CFR)

Management and controls

Risk associated with the consequence of failure of the temporary works come from the location of the temporary works, and what might be affected by the failure.

BS 5975:2019, 6.1.3.1

Constructability

Management and controls

The optimum use of construction knowledge and experience in planning, design, and procurement and field operations to achieve overall project objectives.

CII (1986) Constructability a primer. Texas: Construction Industry Institute;
TWf 2020:02 Constructability: a guide to reducing temporary works

Construction work

Administrative/Management

The carrying out of any building, civil engineering or engineering construction work, including:
• the construction, alteration, conversion, fitting out, commissioning, renovation, repair, upkeep, redecoration or other maintenance (including cleaning which involves the use of water or an abrasive at high pressure, or the use of corrosive or toxic substances), de-commissioning, demolition or dismantling of a structure
• the preparation for an intended structure, including site clearance, exploration, investigation (but not site survey) and excavation (but not pre-construction archaeological investigations), and the clearance or preparation of the site or structure for use or occupation at its conclusion
• the assembly on site of prefabricated elements to form a structure or the disassembly on site of the prefabricated elements which, immediately before such disassembly, formed a structure
• the removal of a structure, or of any product or waste resulting from demolition or dismantling of a structure, or from disassembly of prefabricated elements which immediately before such disassembly formed such a structure
• the installation, commissioning, maintenance, repair or removal of mechanical, electrical, gas, compressed air, hydraulic, telecommunications, computer or similar services that are normally fixed within or to a structure.

CDM Regulations 2015, Reg 2

Contractor

People/Organisation

Anyone (including a non-domestic client) who, in the course or furtherance of a business, carries out, manages or controls construction work.

BS 5975:2019, 3.15

Control measures

Management and controls

Actions and/or activities that are taken to prevent, eliminate or reduce the likelihood of an identified hazard happening. 
The hierarchy of control measures includes the following five steps:
• elimination
• substitution
• engineering controls
• administrative controls
• personal protective equipment.

Management of Health and Safety at Work Regulations 1999, Schedule 1, Reg 4 General principles of prevention;
HSE (2015) L153 Managing health and safety in construction - CDM 2015, Appendix 1

Design

Management and controls

This includes the specification of articles and/or components (e.g. shoring for excavation) or substances (e.g. cement) relating to a structure, and calculations prepared for the purpose of a design.

CDM Regulations 2015, Reg 2

Design brief

Temporary works documents

A document that includes all data and requirements relevant to the design of the temporary works.

BS 5975:2019, 13.2

Design certificate

Temporary works documents

A certificate issued by the designer to indicate that the design is satisfactory and conforms to the design brief, and, where provided, the design statement.

BS 5975:2019, 3.17

Design check

Management and controls

An evaluation of the design to determine whether it conforms to the design brief and, if applicable, design statement, and whether it is adequate to provide a safe 'engineered solution'.

BS 5975:2019, 13.7

Design check certificate

Temporary works documents

A certificate for Category 2 and 3 designs (and potentially required by the organisation for Category 1 designs) that confirms the design conforms to the design brief, states the standards/technical literature used; and lists any constraints to loading conditions imposed. It should be signed by the temporary works design checker and temporary works designer.

BS 5975:2019, 13.7.5

Design review

Management and controls

An evaluation of the design deliverables to make sure they comply with the requirements set out in the design brief. 

Design statement

Temporary works documents

A document prepared by the designer outlining the:
• design requirements
• means by which the design will be developed
• assumptions
• method of analysis
• other controls
• potential to affect / impact operational infrastructure.  

BS 5975:2019, 3.18

Designated individual (DI)

People/Organisation

A senior person in an organisation with responsibility for establishing, implementing and maintaining a procedure for the control of temporary works for that organization.

BS 5975:2019, 3.19

Dynamic wind pressure

Technical

The transformation of wind to dynamic energy when it is stopped by a surface.  The pressure acting on the surface transforms to a force.

Effective length

Technical

Used in determining buckling resistance of a column (or beam) under compression.

BS 5975:2019, 3.21

Effective wind pressure

Technical

The force exerted on a structure by the wind, taking into account the air density and wind velocity per unit area of the structure.

Elastic limit

Technical

The maximum stress a material can withstand before being permanently deformed.

ERIC

Technical

An acronym used to identify a hierarchy for control measures for the design process in order to eliminate or mitigate risks: eliminate, reduce, inform, control (also used: eliminate, reduce, isolate, control).

Management of Health and Safety at Work Regulations 1999, Schedule 1, Reg 4 General principles of prevention;
HSE (2015) L153 Managing health and safety in construction - CDM 2015, Appendix 1

Eurocodes

Temporary works documents

A set of harmonised technical rules developed by the European Committee for Standardization for the structural design of construction works in the European Union.

CPA SFPSG (2014), Guidance on ground conditions, p8

Execution risk (ER)

Management and controls

Risks associated with the construction, use and removal of the temporary works relate to such aspects as workmanship, materials, experience and manner of use.

BS 5975:2019, 6.1.3.1

Factor of safety

Technical

The ratio of failure load to the maximum working load.   

BS 5975:2019, 3.22

Falsework

Technical

A temporary structure used to support a permanent structure under construction until such time as the permanent structure is self-supporting.

BS 5975:2019, 3.23

Fill

Geotechnical

Material used to raise the level of an area, e.g. ash, rubble.

CPA STIG-TIN-201, p9

Force

Technical

An external agent with magnitude and a direction capable of changing the state of rest or motion of a body.

Formation

Geotechnical

The surface of the ground in its final shape, before concreting, but after earthworks.

CPA STIG-TIN-201, p9

Formwork

Technical

The mould into which concrete is poured in order to form a required shape of given dimensions. May be temporary or partly/wholly permanent.

BS 5975:2019, 3.26

Foundation

Technical

A construction for transmitting forces to the supporting ground.

BS 6100-0:2010, Part 3 Building and civil engineering works vocabulary
ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Granular soil

Geotechnical

Soil that predominantly has relatively large angular grains, such as sands and gravels, whose strength is determined by the matrix being held together under its own weight (or applied load).

CPA STIG-TIN-201, p10

Ground

Geotechnical

The soil, rock, and fill existing in place before the execution of construction works.

BS 6100-0:2010, Part 3 Building and civil engineering works vocabulary
ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Ground anchor

Technical

Temporary or permanent device installed at ground level which, when loaded, exerts pressure on a cone of the ground that surrounds its length, providing good resistance to movement. Permanent ground anchors can be up to 70m in length, with a capacity in excess of 3,000 kN.

Ground bearing pressure

Geotechnical

The ultimate (unfactored) bearing capacity the ground can withstand against a load without exceeding the maximum allowable settlement.

Groundwater

Geotechnical

Water contained within, or flowing through, the pores and fabric of soil and fissures in rock.
Groundwater is water that has infiltrated the ground surface and penetrated to the underlying strata and in particular, the water that is contained in the soil or rocks below the water table.

CPA STIG-TIN-201, p10

Guidance

Administrative/Management

Information and instruction on how to apply the requirements within standards or procedures. Guidance is consensual information that originates from any one of several different professional organisations and provides technical information about safe practices and procedures.

Hold point

Management and controls

A stage in the temporary works process where no further progress is to be made until the necessary permit or action has been completed.

BS 5975:2019, 3.29

Hydrostatic pressure

Technical

The pressure exerted by water due to the force of gravity, proportional to its depth.

Implementation plan

Management and controls

A document (or set of documents) that covers the erection/assembly, use, unloading and dismantling of the temporary works, including which inspections, checks, hold points, permits and certifications are required. This may consist of the method statement, task-specific risk assessment, inspection and test plan, checklists and other certification.

BS 5975:2019 14.1.2

Implementation risk

Management and controls

The combination of execution risk and consequence of failure risk.

BS 5975:2019, 6.1.3.1

Implementation risk class

Management and controls

Implementation risk is formed from a combination of execution risk and consequence of failure risk. It may be set out as very low, low, medium or high.

BS 5975:2019, 6.1.3.2

Inspection

Management and controls

An examination by a competent person to make sure that the (temporary) works meet a specified standard, and to identify any risks that are present and decide on the measures required to control those risks.

Inspection and test plan

Management and controls

The documented planning of inspections, tests, checks and surveys to ensure the correct implementation of a process, including temporary works installations.

BS 5975:2019, 3.30

Kentledge

Technical

Material placed on a structure to provide stability by the action of its dead weight. 

BS 5975:2019, 3.33

Lacing

Technical

A component placed horizontally to strengthen a framework, generally providing lateral stability.

BS 5975:2019, 3.34

Lateral restraint

Technical

Internal or external structures used to prevent lateral/horizontal movement of a structure against horizontal forces.

Lateral stability

Technical

The application of lateral force-resisting systems to prevent lateral movement in the event of lateral loads such as wind, concrete pressure, kinetic energy from construction operations.

Limit-state design

Technical

A reliability-based design process that accounts for uncertainties associated with strength properties and applied loads.

ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Load path

Technical

How the loads on the structure are transferred through the structure.

Made ground

Geotechnical

Typically used to refer to an area of ground that has been filled, for example with debris or rubble, as opposed to ground in a natural state.

CPA STIG-TIN-201, p13

Newton

Technical

The unit force, 1 N is the amount of force required to produce an acceleration of one metre per second squared on a mass of one kilogram.

Node point

Technical

The point at which two or more components connect to transfer forces.

Non-cohesive soil (or cohesion-less soil)

Geotechnical

A soil that does not exhibit cohesion (see 'Granular soil').

CPA STIG-TIN-201, p4

Overburden

Geotechnical

Refers to any of the following:
1. Loose, poor quality material overlying rock in a quarry.
2. Term for weight of soil when calculating pressure.
3. Layers of earth and rock that have to be removed to get to formation level.

CPA STIG-TIN-201, p15

Peat

Geotechnical

The surface organic layer of soil consisting of partly decomposed organic matter in the region of 20% to 60%, depending on which authority's definition is used.  Peat is structurally weak for loading.

Peer review

Management and controls

A review of the (temporary) works carried out by independent person(s), separate from a design check.

BS 5975:2019, Table 1

Permanent works

Technical

Parts of a construction that will be used and remain in position for a long time.

https://www.hse.gov.uk/construction/faq-temporary-works.htm

Permanent works designer

People/Organisation

The designer of the permanent works, engaged by either the client or a contractor.

HSE (2015) L153 Managing health and safety in construction - CDM 2015, p30

Permissible stress

Technical

The stress that can be sustained safely by a structural material for the particular condition of service or loading.

BS 5975:2019, 3.36

Permit to load (PTL)

Temporary works documents

A signed statement which releases a hold point. It indicates that:
• the temporary works process has been followed
• the temporary works have been inspected and the 'as installed' temporary works comply with the design
• any modifications to the temporary works have been approved by the designer
• the water, ground and environmental conditions and use are as envisaged by the design.

BS 5975:2019, 3.37 and 14.2.1.3

Permit to proceed

Temporary works documents

A certificate that authorises the release of any hold point, as usually identified on the inspection and test plan, issued by the principal contractor's temporary works co-ordinator or temporary works supervisor

BS 5975:2019, 3.37

Permit to unload
(also referred to as permit to strike and permit to dismantle)

Temporary works documents

A signed statement which releases a hold point. It indicates that:
• the temporary works have been inspected and the 'as installed' temporary works remain compliant with the design
• any modifications to the temporary works during use have been approved by the designer
• a documented safe system of work is in place and has been implemented for the dismantling of any temporary works
• the temporary works are no longer required to be in place, and are ready to be removed.

BS 5975:2019, 3.37

Policy

Administrative/Management

The intentions and direction of an organisation, as formally expressed by its top management.

BS EN ISO 55000:2014, 3.1.8

Pressure

Technical

The force applied to a surface divided by the surface area.

Principal contractor (PC)

People/Organisation

The contractor appointed under the CDM Regulations 5(1)(b) to perform the specified duties in regulations 12 to 14.

CDM Regulations 2015, Reg 2

Principal designer (PD)

People/Organisation

The designer appointed under the CDM Regulations 5(1)(b) to perform the specified duties in regulations 12 to 14.

CDM Regulations 2015, Reg 2

Procedure

Administrative/Management

A specified way to carry out an activity or a process.

BS EN ISO 9000:2015, 3.4.5

Process

Administrative/Management

A set of inter-related or interacting activities that transform inputs into outputs.

Prop

Technical

A compression member used as a temporary support.

BS 5975:2019, 3.39

Publicly available specification (PAS)

Temporary works documents

A standardisation document that closely resembles a British Standard in structure and format, but which has a different development model.

PAS 0

Rate of rise

Technical

Average placing speed of the concrete vertically up the formwork in metres per hour, taken as the average over the pour.

Concrete Society (2012) Formwork: a guide to good practice

Record

Administrative/Management

A document stating results achieved or providing evidence of activities performed.

BS EN ISO 9000:2015, 3.8.10

Re-propping

Technical

Props installed before the falsework is removed to transfer loads to the lower slab or foundation once falsework is dismantled.

BS 5975:2019, 3.41

Residual risks

Management and controls

Any risks which have not been designed out by the temporary works designer. 
The significant residual risks – those risks that are not likely to be obvious to a competent contractor, or are unusual or are likely to be difficult to manage effectively – must be identified by the designer. The temporary works designer must communicate the significant residual risks.

BS 5975:2019, 8.1.3

Risk

Management and controls

The likelihood of a hazard being realised that could cause an adverse event, together with a measurement of its possible severity.

HSE (2013) HSG65 Managing for health and safety, p11

Robustness

Technical

The ability of a structure to withstand events such as fire, explosions, impact or the consequences of human error, without being damaged to extent disproportionate to the original cause.

BS EN 1991-1-7

Safe system of work (SSOW)

Management and controls

A formal procedure that results from systematic examination of a task in order to identify all the hazards. It defines safe methods to make sure that hazards are eliminated or risks minimised.
Safe systems of work are developed by taking into account the people, substances and equipment involved in carrying out a task or activity, identifying all foreseeable hazards and assessing the risks, and then seeking to minimise or eliminate those risks by providing a formal framework for workers to follow.
In construction, the process for producing this formal procedure normally involves a risk assessment followed by the safe method being defined within a method statement.  The key points of the safe system of work are briefed to the operatives in the form of a toolbox talk.

HSE (2013) HSG65 Managing for health and safety

Safe working load

Technical

The maximum unfactored load that can be safely resisted by an item of proprietary equipment. 

BS 5975:2019, 10.6, Note 2

Settlement

Geotechnical

The downward movement of the soil as a result of compression or compaction, or of a building, or other structure supported by that soil. 

ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Shear force

Technical

Load acting across a beam near its support.

The New Penguin Dictionary of Civil Engineering (2005)

Shear stress

Technical

The shear force per unit area, expressed in (say) N/mm².

The New Penguin Dictionary of Civil Engineering (2005)

Significant risks

Management and controls

The significant risks are not necessarily those that involve the greatest risks but those which are not likely to be obvious, are unusual, unexpected or difficult to manage on this occasion.

HSE (2015) L153 Managing health and safety in construction - CDM 2015

Soffit

Technical

The underside surface of a concrete member or slab.

BS 5975:2019, 3.43

Soil

Geotechnical

The mineral material that results from the weathering of rock or decay of vegetation. 

ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Standard

Administrative/Management

A document that sets out how policy objectives are to be delivered and defines the mandatory requirements associated with specific activities and tasks.

Standard solution

Technical

A suitable arrangement for which the basic design work has been carried out and checked, which may be presented in a table, for which no further calculations are required.

BS 5975:2019, 13.10

Strut

Technical

A member in compression.

BS 5975:2019, 3.39

Sub-contractor

People/Organisation

A contractor employed by another contractor to carry out or manage construction work. 

BS 5975:2019, 3.49

Subgrade

Geotechnical

The upper part of the soil, natural or constructed, that supports the loads transmitted by the overlying structure of a road, runway or similar hard surface. 

ISO 6707-1:2020 Buildings and civil engineering works — Vocabulary — Part 1: General terms

Sway

Technical

Horizontal displacement of a structure in relation to the bottom, under the application of a vertical load

BS 5975:2019, 3.50

Sway bracing

Technical

Bracing place to counter the horizontal displacement of the top of a structure in relation to its bottom.

Temporary works

Technical

An 'engineered solution' that is used to support or protect either an existing structure or the permanent works during construction, or to support an item of plant or equipment, or the vertical sides or side-slopes of an excavation during construction operations on site or to provide access.

BS 5975:2019, 5.1.1.1

Temporary works co-ordinator (TWC)

People/Organisation

A competent person with responsibility for the co-ordination of all activities related to the temporary works.

BS 5975:2019, 3.51

Temporary works design check categories

Management and controls

A set of four categories that relate to the level of independence for the design check.  The categories are 0, 1, 2 and 3. The higher the number, the more independent the designer checker must be from the designer.

BS 5975:2019, 13.7.3 and Table 2

Temporary works design checker (TWDC)

People/Organisation

An independent competent person appointed to carry out a design check.

Temporary works designer (TWD)

People/Organisation

The designer of the specified temporary works or an identified part of it.  
The temporary works designer includes any individual or engineering design consultancy who specifies, alters a design, or specifies a particular method of work or material and who assumes the responsibilities, as a designer, under the CDM Regulations 2015 (Regulations 11 and 18).

BS 5975:2019, 8.4

Temporary works lead design checker

People/Organisation

A competent designer, appointed when more than one design checker is involved, with the responsibility for making sure that:
• the design check has considered overall structural robustness at all stages
• all interfaces and interactions between designers have been adequately covered.

BS 5975:2019, 8.4.1.1

Temporary works lead designer

People/Organisation

A competent designer, appointed when there is more than one temporary works designer, with the responsibility for making sure that:
• the overall design is structurally robust at all stages; and
• all interfaces between designers have been adequately considered.

BS 5975:2019, 8.4.2.1

Temporary works manager

People/Organisation

A senior temporary works professional (usually a qualified engineer) who oversees the management of the design, design checking, implementation, loading, maintenance, unloading and removal for large, complex engineering projects. Usually manages several temporary works co-ordinators.

Temporary works register (TWR)

Temporary works documents

Usually in the format of a spreadsheet, the register is used to list all temporary works for a project and to continually monitor the progress of each item. It acts as an aide-memoire to help classify, categorise, design, design check and implement temporary works.

BS 5975:2019, 6.2

Temporary works supervisor (TWS)

People/Organisation

A competent person who is responsible to, and assists, the temporary works co-ordinator.

BS 5975:2019, 3.52

Temporary works type classification

Management and controls

The assessment of risk is classified in accordance with the implementation of the temporary works by the temporary works co-ordinator and each element should be classified as very low, low, medium or high.

BS 5975:2019, 6.1.3.1-6.1.3.5 and Table 1

Tensile force

Technical

The stretching forces on a component made up of tensile stress and tensile strain contracting the cross-section and elongating the component.

TG20:21

Temporary works documents

National Access and Scaffolding Confederation (NASC) publication that provides recognised, standard configurations of tube and fitting scaffolds that have been structurally designed and for which additional bespoke design is not required.

NASC TG20:2021

Third party

People/Organisation

A party, independent of a project, whose procedures have to be followed and whose approval must be obtained, when temporary works proposals affect their assets, users or land ownership.

BS 5975:2019, 3.53

Tie duty

Technical

The capacity that the connections must achieve between the tie and the permanent structure.

Timber grade stress and strength class

Technical

The physical and mechanical properties of timber assessed (graded) under European Harmonised Standards (EN) criteria for bending stress, bending stiffness and density.

Top restraint

Technical

A method by which the stability of falsework is provided by surrounding permanent works, or specifically designed temporary works. 

BS 5975:2019, 3.54

Wind factor

Technical

A means of assessing wind exposure for temporary works, taking into account wind velocity, topographical factors, distance from the shoreline, altitude, probability factor, and duration of use for the temporary works.

BS 5975:2019, 17.1.3 and NASC TG20:21 Design Guide A.1, A.2

Works records

Temporary works documents

All relevant documents that relate to the design, design checking, residual risks, inspection, testing, permitting, erection, safe use, maintenance, dismantling of all items of significant temporary works.

BS5975:2109 9.3.1.1 c)