A risk assessment on a construction site is a careful look at what could cause harm in a piece of work, who could be hurt, and what you will do to stop it happening. The process is commonly broken down into five steps: identify the hazards, decide who might be harmed and how, evaluate the risks and decide on precautions, record your findings and put them into practice, then review and update the assessment. The Management of Health and Safety at Work Regulations 1999 place the legal duty to assess risk on employers, and the same thinking underpins most questions about hazards on site.
Key takeaways
- A hazard is anything that may cause harm, and a risk is the chance that someone is actually harmed, together with how serious the harm could be.
- A common approach has five steps: identify hazards, decide who might be harmed, evaluate risks and decide on precautions, record and implement, then review.
- The Management of Health and Safety at Work Regulations 1999 require employers to make a suitable and sufficient assessment of the risks to their workers and to other people affected by their work.
- A risk assessment is only useful if the controls it lists are actually in place on the day, so check them before you start work.
- Review the assessment whenever the work, the people, the equipment or the conditions change, not just when something goes wrong.
What a risk assessment is, and what it is not
The definitions are simple. A hazard is anything that may cause harm, such as working at height, a trench with unsupported sides, electricity or a moving vehicle. A risk is the chance, high or low, that somebody could be harmed by the hazard, together with an idea of how serious that harm could be.
That distinction matters on site. A pile of loose bricks on a ground-floor slab is a hazard. Whether it creates a high risk depends on who walks past it, whether it is stable and whether anyone is working above it. The assessment is the process of making those judgements in a structured way rather than relying on gut feeling.
HSE also stresses that a risk assessment is about identifying sensible measures to control the risks in your workplace, not about creating huge amounts of paperwork.
The legal duty in plain English
The Management of Health and Safety at Work Regulations 1999 require employers to assess the risks to the health and safety of their employees while they are at work. They also require employers to assess the risks to other people who may be affected by what the business does, which on a construction site includes subcontractors, visitors and members of the public passing the site boundary.
The assessment has to be suitable and sufficient. In practice that means it should cover the significant risks of the actual work, not every imaginable risk, and it should be proportionate to the job. The regulations also expect employers to act on the results, to make arrangements for putting protective and preventive measures in place, and to review the assessment if it is no longer valid or if circumstances change. The regulations also set out general principles of prevention. Among them are avoiding risks where possible, tackling risks at source, and giving priority to measures that protect everyone over measures that protect one person. Our hierarchy of control guide covers that thinking in more detail.
For the exact wording and the record-keeping requirements, read the regulations on legislation.gov.uk and HSE's risk assessment pages rather than relying on a summary.
The five steps in practice
Step 1: Identify the hazards
Walk the work area and look at the task as it will really be done. Look at the ground, the access, the materials, the tools, the people nearby and the weather. Ask the people doing the work what worries them, because they often know about problems that a desk-based review will miss.
Step 2: Decide who might be harmed and how
Think about your own team, but also about other trades, delivery drivers, visitors and the public. Pay attention to people who may be more at risk, such as young or inexperienced workers, new starters and anyone with a health condition that affects the task. Write down how they could be hurt, for example struck by a falling object or injured in a fall.
Step 3: Evaluate the risks and decide on precautions
For each hazard, ask whether it can be removed altogether. If not, decide what is already in place and what more is needed to reduce the risk to an acceptable level. Prefer controls that protect everyone, such as edge protection, over controls that depend on individual behaviour, such as a warning sign. Personal protective equipment sits at the end of the list, as the last line of defence.
Step 4: Record your findings and implement them
Write down the significant hazards, who is at risk and the controls. Then make sure the controls actually happen: the right equipment is on site, the right people are briefed and someone is responsible for each action. HSE's guidance explains what you are expected to record, so check its risk assessment pages for the current position.
Step 5: Review and update
Sites change quickly. Revisit the assessment after an accident or near miss, when the method changes, when new equipment or new people arrive, and when conditions such as weather or ground make the original assumptions wrong.
Worked example: using a scaffold for brickwork
Imagine a bricklayer working from a scaffold on the first lift of a building. The table shows how the five steps turn into practical entries.
| Hazard | Who might be harmed and how | Controls to consider |
|---|---|---|
| Falling from the working platform | Bricklayer, labourer: serious injury from a fall | Scaffold erected by competent people, complete platforms, guardrails and toe boards in place, inspection records checked before use |
| Bricks or tools falling from the platform | People below, including other trades: struck by falling objects | Toe boards, materials stacked safely, exclusion zone below, barriers and signs |
| Scaffold struck by a vehicle or overloaded | Anyone on or near the scaffold: collapse or impact | Traffic routes kept away from the scaffold, loading limits respected, damage reported straight away |
| Unauthorised alterations | Anyone using the scaffold: loss of stability or missing protection | Only competent scaffolders alter it, a clear rule that nobody removes ties or boards, a prompt to report problems |
| Bad weather such as wind or ice | Users of the scaffold: slips and loss of footing | Stop work when conditions make it unsafe, clear or treat surfaces, review the assessment |
The final column is where the judgement lies. Here the precautions that protect everyone, such as guardrails and an exclusion zone, are listed before individual measures. If the work changes, for example if a loading bay is added, the assessment is reviewed and the table updated.
Using the assessment on the day
On a real site the assessment often sits alongside a method statement that sets out how the task will be carried out. Read the two together before you start, and read our guide to method statements for how they fit together. If anything on the ground does not match what the paperwork says, stop and speak to your supervisor. Do not carry on and hope it works out.
A short checklist you can use before starting a task:
- [ ] I have read the risk assessment and method statement for this task.
- [ ] I understand the hazards listed and the controls that apply to me.
- [ ] The equipment, edge protection and barriers described are actually in place.
- [ ] I know who to tell if the conditions or the work change.
- [ ] I know how to stop work and report an unsafe situation.
Practice check
These two questions are original and written for this site. They are not official CITB questions and not an official result.
Question 1. What is the difference between a hazard and a risk?
- A. They mean the same thing.
- B. A hazard is anything that may cause harm, and a risk is the chance of that harm happening and how serious it could be.
- C. A hazard is a legal fine and a risk is an accident.
- D. A hazard is only something that has already caused an injury.
Answer: B. A hazard is the source of potential harm. A risk combines the likelihood of harm with its seriousness.
Question 2. A new crane arrives on site, and the work method changes. What should happen to the existing risk assessment?
- A. Nothing, because it was already signed.
- B. It should be thrown away and never replaced.
- C. It should be reviewed and updated to reflect the change.
- D. It should be given to the public.
Answer: C. Assessments must stay valid. A change in equipment or method is a standard reason to review.
For more practice, see our free practice questions and the operatives test format page. This site is independent and not affiliated with CSCS or CITB.
FAQ
Who has to carry out a risk assessment on a construction site?
Employers are responsible for making sure suitable risk assessments are done, and the Management of Health and Safety at Work Regulations 1999 put that duty on them. In practice the work is often done by a competent person, such as a supervisor or site manager, with input from the people doing the job. Workers are expected to follow the controls and report problems.
Is a risk assessment the same as a method statement?
No. A risk assessment identifies hazards and decides on controls, while a method statement sets out how the task will be done step by step. They are normally used together, and the method statement should reflect the controls found in the assessment. See our method statements guide for the detail.
Does a risk assessment have to be written down?
HSE explains what you are expected to record, and the answer can depend on the size of the organisation. The safe habit on a construction site is to write it down anyway, because it helps with briefings, reviews and proving that controls were considered. Check HSE's risk assessment pages for the current requirements.
How often should a risk assessment be reviewed?
Review it whenever it may no longer be valid, for example after an accident or near miss, or when the work, equipment, people or conditions change. The fifth step is to review and update where necessary. There is no substitute for checking it against the work actually happening.
Sources
Independent guide, not affiliated with, authorised by, approved by or endorsed by CSCS or CITB. Last updated 2026-10-08.