Permits to Work · Mandatory · Construction

Permit to Work — Temporary Works

The Temporary Works Permit authorises the loading and striking of temporary works such as propping, formwork, and falsework in accordance with BS 5975. It confirms that the design has been checked, the installation inspected by the temporary works coordinator, and the structure is safe to load. No temporary works may be loaded or removed without a signed permit.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. BS 5975 remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Document ref	E7 — Permit to Work: Temporary Works
Legal basis	MHSWR 1999 Regulation 3 + CDM 2015 Regulation 19 + BS 5975:2019
Key standard	BS 5975:2019 — Code of practice for temporary works procedures and the permissible stress design of falsework
TWC role	Temporary Works Coordinator (TWC) — appointed to manage the TW process on site, ensure designs are checked, and authorise loading and striking
Permit to load	Formal authorisation confirming that temporary works have been erected in accordance with the design, inspected, and are safe to receive the intended load
Permit to strike	Formal authorisation confirming that permanent works have achieved adequate strength and the temporary works can be safely removed
TW register	Site-wide register of all temporary works — recording design status, erection check, permit to load, and permit to strike for each item

1. Temporary Works — High Consequence Failures

Temporary works are structures or systems erected to support or protect the permanent works during construction. They include formwork and falsework, propping systems, shoring, temporary bracing, excavation support, access scaffolds used as part of the construction sequence, and any other structure that is not part of the completed building but is essential to its safe construction. A failure in temporary works can cause partial or total structural collapse with catastrophic consequences — multiple fatalities, entrapment, and destruction of permanent works already completed.

BS 5975:2019 provides the procedural framework for managing temporary works on construction sites. It establishes the roles of the Temporary Works Coordinator (TWC) and the Temporary Works Designer, and sets out the sequence of design, design check, erection, inspection, permit to load, and permit to strike. The permit to work for temporary works formalises the critical decision points in this sequence — specifically the authorisation to load the temporary works and the authorisation to remove them.

Never remove temporary works without a permit to strike

Premature removal of temporary works — propping struck before concrete has achieved adequate strength, bracing removed before permanent connections are made, falsework dismantled before the slab can span unaided — is one of the most common causes of structural collapse during construction. The permit to strike exists to prevent this. It requires a positive confirmation that the permanent works have achieved the strength assumed in the design before the temporary support is removed. Removing temporary works without this authorisation is gambling with structural integrity.

2. TW PTW — Required Checks

The temporary works permit to work covers two critical authorisation points: the permit to load (authorising the application of load to the temporary works) and the permit to strike (authorising the removal of temporary works). The following table sets out the checks required at each stage.

Permit field	Required content
TW design reference and designer	Reference number of the temporary works design, name of the designer, and confirmation that the design has been independently checked by a competent person (Category 2 or Category 3 check as determined by the risk classification under BS 5975)
Erection check	Confirmation that the temporary works have been erected strictly in accordance with the checked design — including foundation preparation, base plates, sole plates, prop spacing, bracing, and connections. Any deviation from the design must be referred back to the designer before the permit to load is issued
Permit to load — authorisation	Formal written authorisation from the TWC confirming that the TW has been inspected, matches the design, and is safe to receive the intended load. The permit must specify the maximum load, the sequence in which the load will be applied, and any monitoring requirements during loading
Monitoring during service	Requirements for ongoing inspection of the temporary works while under load — including frequency of checks, what to look for (settlement, deflection, loosened connections), and the action to take if movement or distress is observed
Permit to strike — authorisation	Formal written authorisation from the TWC (with input from the structural designer) confirming that the permanent works have achieved adequate strength and the temporary works can be safely removed. For concrete, this typically requires cube test results confirming the specified striking strength has been reached. The permit must specify the sequence of removal
Striking sequence	The order in which temporary works elements will be removed, as specified by the TW designer. Striking must follow the designed sequence to avoid imposing loads on the permanent works in a manner not anticipated by the structural design. Props must never be struck from one area to be reused in another without authorisation

3. Common Mistakes

Props struck before concrete reaches specified striking strength

This is the most common and most dangerous temporary works failure. Concrete gains strength progressively over days and weeks. If props are removed before the concrete has achieved the strength assumed in the structural design, the slab or beam may not be able to support its own weight plus any construction loads. The result can be progressive collapse. The permit to strike must not be issued until cube test results confirm that the required striking strength has been reached — a time-based assumption (e.g. "7 days should be enough") is not acceptable as a substitute for testing.

No Temporary Works Coordinator appointed

BS 5975 requires the appointment of a competent Temporary Works Coordinator on every project where temporary works are used. The TWC is responsible for managing the TW register, ensuring designs are checked, authorising permits to load and strike, and monitoring TW during service. Without a TWC, the procedural controls collapse and decisions about loading and striking are made informally, often by people without the competence to assess the consequences.

TW design not independently checked

BS 5975 classifies temporary works by risk and requires an independent design check proportionate to the risk category. A Category 2 check (independent check by a person other than the designer) is required for most falsework and propping schemes. A Category 3 check (independent check by a separate organisation) is required for high-risk items such as heavy falsework or temporary works supporting occupied structures. Proceeding without the required level of check is a failure to comply with BS 5975 and exposes the project to the risk of a design error that will only become apparent at the point of failure.

Erection deviates from the design without referral

Temporary works must be erected exactly as designed. Any deviation — different prop spacing, substituted components, altered foundation preparation, missing bracing — changes the load capacity and behaviour of the system. Deviations must be referred back to the TW designer for approval before the permit to load is issued. "Close enough" is not an engineering standard. A prop at 1.5m centres instead of the specified 1.2m centres may be carrying 25 percent more load than the design intended.

TW register not maintained or not used

The TW register is the central record of every item of temporary works on site. It records the design status, design check status, erection check, permit to load date, and permit to strike date for each item. Without a maintained register, there is no mechanism to track which items of TW are still under load, which have been struck, and which are awaiting striking authority. On a large project with dozens of propping bays, this quickly becomes unmanageable and items are struck out of sequence or without authorisation.

4. Related Documents

The temporary works permit to work operates alongside several other documents in the compliance framework. The following should be cross-referenced.

Document	Relationship
D11 — RAMS: Temporary Works	The task-specific RAMS for temporary works provides the detailed risk assessment and method statement for TW erection, loading, monitoring, and striking. The permit to work confirms that the controls described in the RAMS have been implemented at each critical stage.
D10 — RAMS: Concrete Pours	Concrete pouring directly loads the temporary works (formwork, falsework, propping). The permit to load must be issued before any concrete is placed, and the concrete pour RAMS must reference the TW permit system.
D12 — RAMS: Scaffolding Erection	Scaffolding used as part of the temporary works scheme (e.g. loading bays, temporary access for formwork erection) must be included on the TW register and subject to the TW permit process.
E1 — PTW: Groundworks and Excavation	Excavation support (sheet piling, propping, trench boxes) is temporary works and must be managed through the TW permit system. The permit to strike for excavation support must not be issued until backfill or permanent retaining works are in place.
B4 — Task-Specific Risk Assessment	The task-specific risk assessment identifies the hazards associated with the temporary works activities. The permit to work cross-references this assessment and confirms that the identified controls are in place.

5. Frequently Asked Questions

Is BS 5975 a legal requirement?▾

BS 5975 is a code of practice, not a statutory instrument. However, compliance with it is the recognised way to discharge the duty under CDM 2015 Regulation 19, which requires that temporary works are designed, erected, and dismantled safely. In any HSE investigation following a temporary works failure, the first question will be whether BS 5975 procedures were followed. Departing from BS 5975 without a documented and justified alternative approach is extremely difficult to defend. In practice, compliance with BS 5975 is treated as the industry standard.

Who can act as the Temporary Works Coordinator?▾

The TWC must be a competent person with sufficient training, experience, and knowledge to manage the temporary works process. They must understand the principles of temporary works design, be able to assess whether erection matches the design, and have the authority to stop work if they identify a problem. The TWC is typically a site manager or site engineer who has completed a recognised TWC training course (such as the CITB TWC course). The role cannot be delegated to someone without the necessary competence, and on larger projects a full-time dedicated TWC may be required.

Can props be moved from one bay to another without authorisation?▾

No. Props must never be moved from one location to another without a permit to strike for the bay they are being removed from and a permit to load for the bay they are being placed in. Moving props without authorisation is one of the most common causes of temporary works failure. The concrete in the bay from which the props are removed may not have achieved adequate strength, and the props being placed in the new bay may not match the design for that location. Both decisions must go through the TWC and the permit system.

What cube test results are needed before striking props?▾

The permit to strike must not be issued until cube test results confirm that the concrete has achieved the striking strength specified by the structural designer. The required striking strength depends on the span, the loading, and the structural design assumptions, but is typically in the range of 10 to 15 N/mm2 for slab props. The structural designer must confirm the required value. Calendar-based rules of thumb (e.g. "strike after 7 days") are not acceptable because concrete strength gain depends on the mix design, ambient temperature, and curing conditions, which vary from pour to pour.

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