Permits to Work · Best Practice · Construction

Permit to Work — Night Works

The Night Works Permit authorises construction activities outside normal working hours, confirming that adequate temporary lighting, welfare facilities, emergency arrangements, and supervision are in place. It records the specific tasks permitted, noise restrictions applicable under local authority consents, and fatigue management measures for night-shift workers.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. MHSWR 1999 remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Document ref	E9 — Permit to Work: Night and Out-of-Hours Works
Legal basis	MHSWR 1999 Regulation 3 + CDM 2015 + Working Time Regulations 1998
When out-of-hours applies	Any work carried out outside the normal site working hours — typically evenings, nights, weekends, and bank holidays. The definition must be set by the principal contractor in the construction phase plan.
Key additional risks	Reduced supervision, fatigue, impaired emergency response, restricted access for emergency services, reduced visibility, security of the site perimeter, lone working where crew numbers are small
Working Time Regs	Night workers must not work more than an average of 8 hours in any 24-hour period (averaged over 17 weeks). Health assessments must be offered to night workers before assignment and at regular intervals.
Communication plan	A specific communication plan is required for out-of-hours work — covering contact details for the site manager on call, emergency services, client representative, and local authority noise contact
Security and access	Out-of-hours work requires a specific security and access plan — who is authorised to be on site, how the site perimeter is secured, and how emergency vehicle access is maintained

1. Out-of-Hours Work — Compounded Risks

Night and out-of-hours work on construction sites introduces a set of compounded risks that do not exist during normal daytime operations. The work itself may be identical — a concrete pour, a steel erection sequence, a service installation — but the environment in which it takes place is materially different. Reduced natural light, smaller crew sizes, fewer supervisory staff, fatigue from disrupted sleep patterns, delayed emergency response, and restricted access for emergency vehicles all increase the likelihood and severity of an incident.

The permit to work for out-of-hours operations does not replace the task-specific RAMS or any other PTW that would be required for the activity during normal hours. It is an additional layer of authorisation that addresses the risks introduced specifically by the out-of-hours context. The permit must confirm that adequate lighting is in place, that supervision is sufficient, that the workforce has been assessed for fatigue, that the emergency plan has been adapted for out-of-hours conditions, and that the client and relevant authorities have been notified.

Fatigue is a safety-critical factor — not a welfare issue

Research consistently demonstrates that fatigue impairs cognitive function, reaction time, and decision-making to a degree comparable with alcohol intoxication. A worker who has been awake for 17 hours performs at a level equivalent to a blood alcohol concentration of 0.05 percent. After 24 hours, this rises to the equivalent of 0.10 percent — above the legal drink-drive limit. Night workers operating plant, working at height, or carrying out safety-critical tasks under fatigue conditions represent a foreseeable and serious risk that must be assessed and managed through the permit system. The Working Time Regulations 1998 set maximum average night working hours at 8 hours per 24-hour period precisely because of this evidence.

2. Out-of-Hours PTW — Required Content

The following table sets out the fields that a night and out-of-hours permit to work should contain. Each field addresses a risk that is either unique to or significantly increased by out-of-hours working.

Permit field	Required content
Scope of works	Specific description of the work to be carried out during the out-of-hours period, including location, duration, and any other permits required (hot works, WAH, confined space, lifting)
Justification	Documented reason why the work must be carried out outside normal hours — highway authority requirement, noise-sensitive works, programme-critical concrete pour, client operational constraint, or other specific justification
Lighting assessment	Confirmation that temporary lighting is adequate for the work being carried out — minimum lux levels for the task type, coverage of access routes, welfare areas, and emergency escape routes. Lighting must not create glare or deep shadows that impair visibility
Supervision arrangements	Name and contact details of the competent supervisor who will be present on site throughout the out-of-hours work. The supervisor-to-worker ratio must be assessed and documented. For high-risk activities, the level of supervision should be at least equivalent to daytime operations
Fatigue management	Confirmation that the workforce has been assessed for fitness to carry out night work, that shift patterns comply with the Working Time Regulations 1998 (maximum average 8 hours in 24), that adequate rest breaks are scheduled, and that workers are not carrying out consecutive night shifts without adequate rest
Emergency plan (out-of-hours)	Adapted emergency plan confirming: the location of the nearest A and E department, estimated emergency services response time for out-of-hours attendance, on-site first aid provision, fire plan adapted for reduced occupancy, and the procedure for accessing the site for emergency vehicles (gates unlocked, route lit, banksman available)
Communication plan	Contact details for the on-call site manager, the principal contractor duty manager, the client representative, the emergency services, and the local authority noise and environmental contact. Two-way radio or mobile phone coverage confirmed across the work area
Security and access control	Who is authorised to be on site during the out-of-hours period, how the site perimeter is secured, how personnel are signed in and out, and how unauthorised access is prevented. CCTV or security patrol arrangements where applicable
Noise and environmental controls	Confirmation that any local authority noise conditions or Section 61 (Control of Pollution Act 1974) prior consent conditions are being complied with. Noise monitoring arrangements, vibration limits, and restrictions on certain types of plant or activity during night hours
Permit validity and sign-off	Start time, end time, maximum duration. Signature of the authorising person (site manager or PC representative) confirming that all out-of-hours controls are in place. Cancellation sign-off confirming the site has been secured and left safe on completion

3. Common Mistakes

Daytime RAMS used without adaptation for night conditions

A RAMS written for daytime operations does not automatically cover the same activity carried out at night. The risk profile changes materially — reduced visibility affects hazard identification, fatigue impairs decision-making, emergency response times increase, and communication becomes more difficult. The permit system must require that each task-specific RAMS is reviewed and supplemented with night-specific controls before out-of-hours work is authorised. Issuing a night permit that simply cross-references the daytime RAMS without this review is a failure of the system.

Inadequate lighting treated as acceptable

Temporary site lighting for night work is frequently insufficient for the task being carried out. General area lighting that provides enough light to walk safely does not necessarily provide enough light to carry out precision tasks, read gauges and dials, identify hazards, or operate plant safely. The permit must specify the minimum lighting levels for each work area and access route, and the supervisor must verify that these levels are achieved before the permit is issued. Dark spots, deep shadows, and glare from poorly positioned lights are all indicators that the lighting assessment has not been carried out properly.

No fatigue risk assessment for the workforce

Putting workers onto a night shift without assessing their fitness for night work is a breach of the Working Time Regulations 1998 and a foreseeable safety risk. Workers who have already completed a full daytime shift, workers who are not acclimatised to night working, and workers with medical conditions affected by disrupted sleep are all at elevated risk. The permit must confirm that the fatigue assessment has been carried out and that the shift pattern complies with the Regulations.

Emergency plan not adapted for out-of-hours conditions

The daytime emergency plan assumes that site management, first aiders, fire marshals, and multiple personnel are available to respond. At night, with a smaller crew and no management presence beyond the duty supervisor, the response capability is significantly reduced. The out-of-hours emergency plan must account for smaller numbers, identify who fills each emergency role, confirm that first aid equipment and trained first aiders are available, and verify that emergency services can access the site (gates open, route lit, postcode or grid reference available for the dispatcher).

Section 61 consent conditions not checked

Many construction sites operating at night do so under a Section 61 prior consent from the local authority, which imposes specific conditions on noise levels, permitted hours, types of plant, and monitoring requirements. Operating in breach of these conditions is a criminal offence under the Control of Pollution Act 1974 and can result in enforcement action by the local authority. The permit must confirm that the Section 61 conditions have been reviewed and that the planned work complies with them. A copy of the consent should be available on site during the out-of-hours period.

4. Related Documents

The night and out-of-hours permit to work operates alongside several other documents in the compliance framework. The following should be cross-referenced.

Document	Relationship
D14 — RAMS: Night Works	The task-specific RAMS for night works provides the detailed risk assessment addressing visibility, fatigue, security, and environmental controls. The out-of-hours permit confirms that these controls are in place for each specific night shift.
E10 — PTW: Lone Working	Out-of-hours work with small crew numbers may result in lone working situations. Where a worker is isolated from colleagues, a separate lone working permit and check-in system must be in place.
E2 — PTW: Confined Space	Confined space entry during out-of-hours work is particularly high risk due to reduced rescue capability. The confined space permit must be supplemented with night-specific rescue arrangements.
E3 — PTW: Hot Works	Hot works during night shifts require particular attention to the fire watch post-work period, which may extend beyond the end of the shift. The fire watch must be maintained for the full required duration regardless of shift patterns.
A3 — Construction Phase Plan	The construction phase plan must define what constitutes out-of-hours work for the project and set out the arrangements for managing it. The out-of-hours permit implements these arrangements for each specific shift.

5. Frequently Asked Questions

Is a separate permit required for night work if the daytime RAMS covers the task?▾

Yes. The daytime RAMS covers the task hazards, but it does not address the additional risks introduced by working at night or outside normal hours. Reduced visibility, fatigue, smaller crew sizes, impaired emergency response, and security considerations are all material changes to the risk profile that require separate assessment and authorisation. The out-of-hours permit is an additional document that supplements the task-specific RAMS and any other permits required for the activity.

What are the Working Time Regulations requirements for night workers?▾

Under the Working Time Regulations 1998, a night worker must not work more than an average of 8 hours in any 24-hour period, averaged over a 17-week reference period. Where the work involves special hazards or heavy physical or mental strain, the 8-hour limit is an absolute maximum for any single 24-hour period and cannot be averaged. Employers must offer a free health assessment to workers before they begin night work and at regular intervals thereafter. Records of night working hours and health assessments must be maintained. Workers have the right to be transferred to daytime work where a medical practitioner advises that night work is affecting their health.

What lighting levels are required for night construction work?▾

There is no single standard that prescribes exact lux levels for all construction activities. However, HSE guidance and BS 12464-2 (Lighting of outdoor work places) provide benchmarks. General circulation areas require a minimum of 20 lux. Areas where simple visual tasks are carried out (material handling, general construction) require at least 50 lux. Areas where more detailed work is carried out (reading drawings, operating controls, making connections) require at least 100 lux. High-precision tasks may require 200 lux or more. Access routes, stairways, and emergency escape routes must be lit to at least 20 lux. The lighting must be uniform, free from glare and deep shadows, and positioned so that it does not dazzle plant operators or create blind spots.

Do Section 61 noise consent conditions apply at night?▾

Yes. Section 61 of the Control of Pollution Act 1974 allows a contractor to apply to the local authority for prior consent to carry out construction work, specifying the methods, hours, and noise levels. Where consent has been granted, the conditions are legally binding. Night work conditions are typically more restrictive than daytime conditions — lower noise limits, restrictions on certain types of plant (e.g. piling rigs, impact breakers), and requirements for continuous noise monitoring at the site boundary. Operating in breach of Section 61 conditions is a criminal offence and can result in enforcement notices, prosecution, and injunctions preventing further night work.

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