A Permit to Load should not create permission simply because somebody has signed a form. It should record that the temporary works have reached a defined engineering hold point and that the conditions for the next change in load path have been satisfied. The same principle applies at the other end of the temporary works lifecycle. Before props, falsework, shoring or other temporary support is unloaded or removed, the project needs evidence that the structure can safely accept the resulting change in forces. That makes Permit to Load and Permit to Unload controls much more than paperwork. They are the point where design, checking, inspection, site conditions and construction sequence are brought together before an irreversible site action takes place.
Construction professionals reviewing a Permit to Load before a temporary works hold point is released. Image: London Construction Magazine.
Terminology matters: BS 5975-1:2024 uses Permit to Load and the wider concept of a Permit to Unload. “Permit to Strike” remains common construction terminology, particularly for concrete formwork and falsework, but striking is one application of the wider unloading control process.
What the Permit System Is Actually Controlling
The current temporary works framework is split between BS 5975-1:2024, covering management procedures for temporary works, and BS 5975-2:2024, covering falsework design and implementation. The legal position is slightly different. The Construction (Design and Management) Regulations 2015 do not contain named statutory documents called a Permit to Load or Permit to Strike. CDM instead imposes duties around planning, managing and coordinating construction work and maintaining structural stability. The Health and Safety Executive explains that BS 5975 provides one recognised way of managing temporary works effectively. This distinction matters: the safety duty is statutory; the BS 5975 permit system is a structured means of controlling how those duties are discharged. For a wider explanation of the individual documents, see our existing guide to temporary works permits under BS 5975. The focus here is different: how the control should operate on a live project.
A Permit to Load Is the End of a Verification Sequence
Before a temporary works system is loaded, the project should be able to demonstrate that the arrangement being released is the arrangement that was designed and checked. Depending on the temporary works item, that normally means confirming the current design and revision, completion of the required design check, correct installation, appropriate inspection, acceptable foundations or bearing surfaces, correct bracing and restraint, completion of relevant test or inspection hold points, and resolution of any deviations that could affect performance.
| Control Stage | Question Before Release |
|---|---|
| Design | Is the live temporary works design appropriate for the actual site conditions and intended loading? |
| Design check | Has the required check been completed in accordance with the project's temporary works procedure? |
| Installation | Has the temporary works been constructed in accordance with the approved information? |
| Inspection | Has a competent inspection identified and closed relevant defects or deviations? |
| Supporting evidence | Are any required anchor tests, concrete-strength evidence, surveys, torque checks or other project-specific records available? |
| Release | Is the person authorised under the temporary works procedure satisfied that the hold point can be released? |
A checked design alone does not answer the last question. The structure on site may contain a missing brace, a changed foundation condition, an altered connection, an obstruction or an unapproved modification. This is why a design check and a Permit to Load perform different functions. We examined that distinction separately in Permit to Load vs Permit to Proceed.
Permit to Unload and Permit to Strike: The Second Hold Point
Removal can be just as critical as loading because unloading temporary works changes the structural load path. For falsework supporting a concrete slab, striking transfers load from the temporary support system into the permanent structure. On excavation support, façade retention or structural propping, unloading may similarly redistribute forces into permanent works or other parts of the temporary works arrangement. The release therefore needs to be based on the designer's criteria and the actual condition of the works, not a generic calendar rule.
There is no universal 7-day, 14-day, 28-day, 70% or 75% rule that automatically authorises striking. The required strength, sequence, construction loading, backpropping and load redistribution are project-specific engineering matters.
Concrete test results may form part of the evidence, but a cube result is not itself a Permit to Strike. The relevant question is whether the structure has satisfied the project-specific criteria for the proposed change in support condition. That can include early-age strength information, maturity assessment, construction loading, backpropping arrangements, the permanent works design assumptions and the precise sequence in which support is removed. For the detailed engineering issues behind this decision, see When Can Concrete Props Be Removed? UK Site Guide.
The Correct Question Is Not “Is the Concrete Old Enough?”
The better question is: has the permanent structure reached the condition assumed by the striking or unloading design, and can the next load path safely be introduced? That is particularly important on multi-storey concrete frames where props and backprops distribute construction loads through several levels. Removing one level can affect more than the slab immediately above it.
Who Inspects, Who Authorises and Who Can Say No?
On projects using BS 5975 management procedures, the Temporary Works Coordinator sits at the centre of the control system. A Temporary Works Supervisor may undertake detailed site inspections and report the condition of the installation, but the project procedure should make the formal authority for releasing the hold point unambiguous. The temporary works designer and checker establish and verify the engineering requirements. They do not normally replace the site management release process by signing a permit simply because the design has been completed.
The Designated Individual operates at organisational governance level rather than routinely signing every site permit. Project procedures may introduce additional approval tiers for particularly high-risk temporary works, but those should be recognised as company controls rather than assumed to be universal BS 5975 requirements.
| Role | Typical Permit Interface |
|---|---|
| Temporary Works Designer | Defines the engineering arrangement, limits, sequence and relevant release criteria. |
| Design Checker | Completes the required independent check appropriate to the design category. |
| TWS | May inspect the physical works and confirm findings to the TWC in accordance with the project's procedure. |
| TWC | Coordinates the temporary works control process and authorises the relevant release in accordance with the written procedure. |
| Site / Project Management | Plans delivery and resources but should not substitute programme pressure for an unresolved technical hold point. |
If the TWC is not satisfied that the release conditions have been met, the answer should remain no until the issue is resolved through the project's defined escalation route. Concrete wagons waiting outside the gate, a crane already booked or a programme milestone does not change the engineering condition of the temporary works. Where subcontractors have their own temporary works coordinators and procedures, those arrangements need to be integrated into the Principal Contractor's overall coordination system. Parallel permit systems that do not communicate with one another create exactly the interface risk the control process is supposed to prevent.
Where Permit Systems Start to Fail in Practice
The weak point is often not the absence of a form. It is the gap between the form and the actual condition on site. Recurring control failures include permits prepared retrospectively after loading has started, copied inspection sheets for repetitive bays, construction from preliminary drawings, braces or props altered after inspection, outdated drawing revisions attached to permits, verbal releases that are never formally recorded, and programme pressure to sign before outstanding technical actions have been closed.
Another dangerous failure occurs after the permit has been issued. A permit only relates to the conditions that existed when the hold point was released. If the arrangement is subsequently changed in a way that affects the design assumptions, the earlier release cannot simply be treated as continuing approval for the modified system.
A signed permit does not make an unauthorised later alteration safe. Relevant changes should be reviewed, incorporated into the controlled design information where necessary, reinspected and released through the project's temporary works procedure before the next affected activity proceeds.
Digital Permits Are Not the Problem
A permit does not become safer simply because it is printed on paper. Electronic permit systems can provide a stronger audit trail where they reliably record the item, design revision, inspection status, authorised user, date, time and supporting evidence. What matters is that the electronic process preserves the engineering hold point. A digital signature should not become a mechanism for approving temporary works remotely without adequate inspection simply because photographs have been uploaded to an app.
Likewise, an informal WhatsApp message or telephone call may be useful for communication, but it should not replace the controlled authorisation required by the project's written procedure. Retrospective documentation is particularly problematic. If work has already been loaded without the required release, signing the permit afterwards cannot turn that earlier uncontrolled action into prior authorisation. The event should instead be dealt with transparently under the project's management and incident processes.
What a Useful Permit Should Record
A good permit does not need to be a twenty-page corporate checklist. It needs enough information to make the hold point unmistakable and auditable. Useful information normally includes the temporary works reference, exact location, current design revision, relevant check status, inspection reference, activity or load being authorised, any limitations or sequence conditions, supporting test evidence where applicable, outstanding actions that must remain closed, the authorised person and the date and time of release. The objective is not to accumulate signatures. It is to make clear what has been authorised, against which design information, under what conditions, by whom and when.
Practical permit test:
If a supervisor arriving on the next shift cannot tell exactly what temporary works item has been released, what it may now be subjected to, which design revision applies and what restrictions remain, the permit system is not communicating the control clearly enough.
If a supervisor arriving on the next shift cannot tell exactly what temporary works item has been released, what it may now be subjected to, which design revision applies and what restrictions remain, the permit system is not communicating the control clearly enough.
Permit to Load and Permit to Strike: Key Questions
Is a Permit to Load legally required by CDM 2015?
CDM 2015 does not prescribe a document with that specific name. The regulations impose wider duties around safe management and structural stability. BS 5975 provides a recognised management framework for controlling temporary works.
CDM 2015 does not prescribe a document with that specific name. The regulations impose wider duties around safe management and structural stability. BS 5975 provides a recognised management framework for controlling temporary works.
Is Permit to Strike the formal BS 5975 term?
For the wider temporary works lifecycle, Permit to Unload is the more appropriate overarching term. Permit to Strike remains widely used for the removal of formwork or falsework in concrete construction.
For the wider temporary works lifecycle, Permit to Unload is the more appropriate overarching term. Permit to Strike remains widely used for the removal of formwork or falsework in concrete construction.
Can a TWS inspect temporary works before loading?
Yes, where the project's procedure assigns that inspection function to a competent TWS. The inspection record then forms part of the information considered by the TWC before the hold point is released.
Yes, where the project's procedure assigns that inspection function to a competent TWS. The inspection record then forms part of the information considered by the TWC before the hold point is released.
Can a site manager simply overrule a refused permit?
Programme authority does not replace the technical release required by the temporary works procedure. Any disagreement should be escalated through the defined management and engineering route rather than bypassing the hold point.
Programme authority does not replace the technical release required by the temporary works procedure. Any disagreement should be escalated through the defined management and engineering route rather than bypassing the hold point.
Does a concrete cube result automatically permit striking?
No. Concrete-strength evidence needs to be considered against the project-specific striking criteria, structural condition, loading sequence and any backpropping requirements.
No. Concrete-strength evidence needs to be considered against the project-specific striking criteria, structural condition, loading sequence and any backpropping requirements.
Can temporary works be altered after a Permit to Load?
Only within the limits of the approved information and procedure. A change affecting the design assumptions or structural behaviour should be reviewed before the altered arrangement is relied upon.
Only within the limits of the approved information and procedure. A change affecting the design assumptions or structural behaviour should be reviewed before the altered arrangement is relied upon.
Can a permit be electronic?
Yes, provided the project's procedure allows it and the system gives a reliable, auditable record of the authorised item, current status, supporting evidence, identity and timing of the release.
Yes, provided the project's procedure allows it and the system gives a reliable, auditable record of the authorised item, current status, supporting evidence, identity and timing of the release.
Can a permit be signed retrospectively?
A later signature cannot recreate a hold point that was bypassed before loading or unloading occurred. Any unauthorised action should be recorded and managed as such rather than disguised as prior approval.
A later signature cannot recreate a hold point that was bypassed before loading or unloading occurred. Any unauthorised action should be recorded and managed as such rather than disguised as prior approval.
What is the most important principle?
A permit should record an engineering decision that has already been justified by design, checking, inspection and site evidence. The signature is the final control action, not the technical basis for the decision.
A permit should record an engineering decision that has already been justified by design, checking, inspection and site evidence. The signature is the final control action, not the technical basis for the decision.
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Expert Verification & Authorship: Mihai Chelmus Founder & Editor, London Construction Magazine | Construction Testing & Investigation Specialist |