Temporary works compliance checklist

BS 5975 roles, excavation support, inspection frequencies, and permit references. Built for TWCs, site agents, and anyone who signs off excavations.

BS 5975 duty holders

Every construction project with temporary works needs these roles filled. On a small project one person can hold multiple roles, but each role must be explicitly assigned and documented.

TWC

Temporary works coordinator

Appointed by the principal contractor

• Maintains the TW register for the project
• Ensures every TW item has a design and a design check
• Issues permits to load and permits to strike/dismantle
• Inspects or delegates inspection of TW on site
• Signs off completion before the TW is loaded or struck

Competence: CSCS TWC card (CITB-accredited training), or equivalent experience documented and assessed. Must understand the categories of TW on their project.

TWD

Temporary works designer

Must be a competent engineer

• Designs the temporary works to a recognised standard
• Produces drawings, calculations, and a design brief
• Specifies materials, loading limits, and erection sequence
• Responds to site queries and design changes

Competence: Chartered or incorporated engineer (CEng/IEng) with TW design experience, or a specialist TW design consultancy. The TWD cannot also be the independent design checker.

TWS

TW supervisor (site)

Supervises erection, use, and striking

• Erects TW to the designer's drawings and sequence
• Reports deviations or problems to the TWC immediately
• Ensures no loading before the permit to load is issued
• Ensures no striking before the permit to strike is issued

Competence: Site agent, foreman, or supervisor with practical knowledge of the TW type being erected. CSCS Supervisor (gold) card minimum. Must be briefed on the specific TW design before work starts.

Does this work need a TWC?

BS 5975 applies to all temporary works. In practice, the following categories require a formally appointed TWC with a documented procedure.

Excavation support

Trench boxes, sheet piling, timber shoring, hydraulic frames, propped excavation faces

Formwork and falsework

Any formwork system supporting wet concrete, falsework towers, table forms, climbing systems

Temporary propping

Propping existing structures during demolition, alteration, or underpinning

Crane bases and heavy plant hard standings

Ground bearing assessments and temporary platforms for cranes, piling rigs, or concrete pumps

Temporary access structures

Temporary bridges, ramps, platforms, and access decking (scaffolding has separate regulations under NASC/TG20)

Temporary works to existing structures

Needle beams, dead shores, raking shores, temporary steelwork supporting existing buildings during alterations

Cofferdams and caissons

Temporary water-retaining structures for construction in or near water

Ground anchors and soil nails (temporary)

Temporary ground retention during construction, to be de-stressed or removed on completion

0 of 8 categories checked. Select the TW categories present on your project.

Excavation support selector

Select your excavation depth and ground type. You'll get the recommended support method, indicative cost range, and key inspection points.

Excavation depth

Ground type

Recommended support

Battering or stepping

Safe batter angle

45° (1:1)

Indicative cost

Low

Excavation volume only

Inspection frequencies by TW type

Minimum inspection intervals per CDM 2015 and BS 5975. Your site-specific TW procedure may require more frequent inspections.

TW type	Routine inspection	After adverse event	By whom
Excavations (all types)	Start of every shift + at least every 7 days	After heavy rain, vibration from plant, changes to surcharge loading, or any event affecting stability	Competent person (site agent, TWC, or delegated supervisor)
Formwork / falsework	Before each concrete pour (permit to load) + during the pour	After any movement, settlement, or reported defect	TWC or TW supervisor
Temporary propping	Daily visual check + formal inspection weekly	After impact, vibration, or change to loading	TWC
Crane bases / hard standings	Before each crane erection or relocation	After heavy rain or change to ground conditions	Crane supervisor + TWC
Cofferdams	Every shift + continuous monitoring of water levels	After tidal events, flood, or change to river level	TWC with specialist input

CDM 2015 Regulation 22 sets the legal minimum for excavation inspections. BS 5975 sets the framework for all other TW types. Inspection records must be kept on site and be available for HSE inspection. Use Form F91 (excavation) or your company's equivalent.

The permit process

BS 5975 requires a formal permit system for loading and striking temporary works. Here's what each permit covers and what the TWC checks before signing.

Permit to load

Issued by the TWC before the temporary works can accept their design load (e.g. before a concrete pour into formwork, before placing fill against a retaining structure).

TWC checks before signing

• TW erected to the approved design drawing
• Independent design check completed and signed
• Foundation/bearing conditions match assumptions
• All connections, pins, and wedges secure
• No deviations from the design (or deviations agreed with the TWD)
• Monitoring points in place (if specified)

Permit to strike / dismantle

Issued by the TWC before temporary works can be removed. Premature striking is one of the most common causes of TW-related collapses.

TWC checks before signing

• Permanent works have reached the required strength (cube results for concrete)
• Minimum curing period has elapsed (typically 3-7 days for formwork to slabs)
• Structural engineer has confirmed the element is self-supporting
• Striking sequence agreed (progressive release, not sudden removal)
• Adjacent TW not affected by the removal
• Exclusion zone established below the TW being struck

RIDDOR reportable events (TW-related)

These temporary works incidents must be reported to the HSE under RIDDOR within 10 days (or immediately for fatalities and specified injuries).

Event	Reporting deadline	Examples
Collapse of falsework	Immediate	Partial or complete failure of falsework towers supporting formwork, regardless of whether anyone was injured
Collapse of scaffold over 5m	Immediate	Partial or complete collapse of any scaffold exceeding 5m in height
Collapse of excavation wall	Immediate (dangerous occurrence)	Collapse of an excavation face that was deep enough to bury or trap a person, even if no one was in the trench at the time
Collapse of building or structure	Immediate	Unplanned collapse of any wall, floor, or structural element during construction, including collapse caused by TW failure
Over-7-day injury	Within 15 days	Any injury caused by TW failure that results in more than 7 consecutive days off work (not counting the day of the accident)

HSE prosecution examples

Trench collapse, London, 2023. A groundworker was buried up to his chest when 2.4m of unsupported trench collapsed in soft clay. No trench support was on site. The subcontractor was fined £120,000 under CDM 2015 Regulation 22 (safe excavations). The principal contractor was fined £80,000 for failing to plan and manage the work. The excavation had no support design, no TWC appointment, and no inspection regime.

Formwork collapse, Birmingham, 2022. A suspended slab formwork system collapsed during a concrete pour, injuring three workers. The falsework had been modified on site without reference to the TWD, and the permit to load had been signed before the modifications were checked. The principal contractor was fined £200,000. The judge noted that the company had a TW procedure on paper but had not followed it.

Excavation collapse near live carriageway, M6, 2021. A 3.5m deep excavation adjacent to a live motorway carriageway collapsed overnight due to heavy rain, taking a section of hard shoulder with it. No inspection had been carried out after the rainfall event. National Highways issued an improvement notice and the subcontractor received a fine of £90,000. The post-incident investigation found that the TW design had not accounted for the surcharge loading from highway traffic.

Formwork striking times

Minimum periods before formwork removal, per BS EN 13670 and typical UK practice. These assume CEM I concrete cured at an average temperature of 15-20°C. Cold weather extends these periods significantly.

Element	Side formwork (non-load-bearing)	Soffit (load-bearing)	Notes
Walls and columns	12-18 hours	N/A	Concrete must be strong enough to resist damage during stripping. Wait longer in cold weather.
Beam sides	12-18 hours	N/A	Side forms only. Soffits remain until the beam is self-supporting.
Slab soffits (props remain)	N/A	3-4 days	Soffit boards can be removed if back-propping is in place. Props carry the load until the slab reaches design strength.
Slab soffits (props removed)	N/A	7-14 days	Cube test results required. Concrete must reach 75% of design strength before props are fully removed.
Beam soffits	N/A	14-21 days	Beams are more critical than slabs. Always verify with cube results. Never strip beam soffits based on time alone.

These are guidance values, not fixed rules. Your structural engineer or TWD sets the actual striking criteria for the project. The TWC issues the permit to strike only when the criteria are met. If average daily temperature drops below 5°C, double the times shown. Below 0°C, do not assume any strength gain until the concrete thaws.

Sources

BS 5975:2019 Code of practice for temporary works procedures and the permissible stress design of falsework
CDM 2015 Construction (Design and Management) Regulations 2015 (Regulation 22: Excavations)
RIDDOR 2013 Reporting of Injuries, Diseases and Dangerous Occurrences Regulations
Temporary Works Forum guidance documents and toolbox talks
CIRIA C760 Guidance on embedded retaining wall design
HSE: Excavation safety guidance for employers and workers

Built by Rospower Projects, a specialist groundworks and civil engineering contractor. 35+ years on site.

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