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Risk Assessment for Construction Sites: A Practical Walkthrough

Last reviewed: 24 February 2026

A risk assessment written at your kitchen table, before you've seen the site, is a risk assessment that doesn't reflect reality. The regulations require the assessment to be "suitable and sufficient" — and that means based on the actual conditions, not assumptions.

This guide is about the practical process of assessing a construction site: what to check when you arrive, what to ask the client or principal contractor, and how to turn your observations into a written assessment that holds up.

For the document structure and legal requirements, see our risk assessment template guide. This guide focuses on the site assessment itself — the thinking that goes into the document.

Before you visit the site

Gather whatever information exists before you arrive. This saves time on site and helps you know what to look for:

  • Pre-construction information — on projects with a principal designer, they're required to provide this under CDM 2015 Regulation 4(4). It should include existing hazards (asbestos, contaminated land, underground services, structural concerns).
  • Existing surveys — asbestos management survey (required for all non-domestic buildings under Regulation 4 of the Control of Asbestos Regulations 2012), structural surveys, any existing EICR (Electrical Installation Condition Report).
  • Previous RAMS — if other contractors have already worked on site, their RAMS may flag hazards relevant to your scope.
  • Site drawings — general arrangement, service routes, access plans.
  • Client requirements — some clients and principal contractors have specific RAMS formats, hazard categories, or additional documentation requirements. Ask before you write.

If none of this is available (common on smaller domestic projects), your site visit becomes more important.

The site walk: what to check

Arrive at the site before you start writing the risk assessment. If that's not possible (tendering for work on a site you can't access yet), note what you can't verify and plan to update the assessment after your first visit.

Access and egress

  • How do you get to the work area? Stairs, scaffolds, ladders, hoists?
  • Is the access route shared with the public, the client's staff, or other trades?
  • Can your van get close enough for material handling, or is there a long carry distance?
  • Are there any access restrictions — security gates, sign-in procedures, permit requirements?
  • Is the access route maintained? Muddy tracks, uneven ground, poorly lit corridors all affect your risk assessment.

The work area itself

  • Height — will you be working above 2m? What's below you? What edge protection exists or needs to be installed?
  • Headroom — loft spaces, basements, plant rooms. Limited headroom means head injury risk, restricted movement, and difficulty evacuating in an emergency.
  • Lighting — is there adequate natural or artificial light? Will you need temporary lighting?
  • Ventilation — especially relevant if using solvents, adhesives, or generating dust. An enclosed room with no windows changes your control measures significantly.
  • Condition of the structure — is the building sound? Old properties may have loose plaster, rotten timbers, or unstable walls. New builds under construction may have incomplete structural elements.
  • Temperature — loft spaces in summer, unheated sites in winter. Both create health risks (heat stress, cold stress) that affect working capacity and concentration.

Existing services

This is where serious hazards hide:

  • Electrical — is the existing supply live? Where's the consumer unit or distribution board? Are there overhead power lines near scaffold or crane positions? On older buildings, is the wiring in safe zones or run randomly through walls?
  • Gas — where's the meter and supply? Will your work come near gas pipes?
  • Water — supply and waste pipe routes, especially relevant if you're drilling through walls or lifting floors.
  • Underground services — on external works, check for drainage, buried electrical cables, telecoms, and gas. Ask the client for service drawings. If none exist, CAT scan before any excavation or ground penetration.

Other people on site

  • Other trades — who else is working there? What are they doing? Will your work create risks for them (dust, noise, falling objects) or vice versa?
  • Occupants — is the building occupied? Homeowners, office workers, patients, pupils? Occupied buildings restrict when you can do noisy or dusty work and require protection of escape routes.
  • Public — can members of the public access the area? Children near schools, pedestrians near street-facing scaffolds, vehicles near site access.

Environmental factors

  • Weather exposure — will you be working outdoors? Wind affects working at height (most scaffolding operations cease above 35-40 km/h). Rain makes surfaces slippery. Frost affects ground conditions and scaffolding.
  • Ground conditions — soft ground affects scaffold base stability. Sloping ground affects material handling. Muddy conditions affect access.
  • Contamination — industrial sites may have contaminated ground. Old buildings may have lead paint, PCBs in older electrical equipment, or chemical residues.

Turning observations into a risk assessment

Match hazards to tasks

Don't just list everything you saw. Map each hazard to a specific task in your scope of work. "Asbestos in textured ceiling coating" only matters if your work involves disturbing that coating. If you're installing sockets on the wall below and won't touch the ceiling, it's still worth noting (in case the scope changes) but it's not a hazard you need detailed controls for.

Rate risks honestly

Use whatever matrix your company or the PC requires (3x3 or 5x5 are both common). The key is honesty:

  • A fall from a 6m scaffold has catastrophic severity whether or not you have edge protection. Controls reduce the likelihood, not the severity.
  • If every hazard in your assessment comes out at "Low" residual risk, either the job is genuinely very low risk, or you're not rating honestly. A domestic bathroom refit with hot works, manual handling, asbestos risk, and COSHH substances is not an all-green assessment.

For realistic rating examples across different project types, see our construction risk assessment examples.

Be specific in control measures

The difference between a credible risk assessment and a rejected one is almost always the control measures. Compare:

Vague: "Appropriate PPE will be worn."

Specific: "RPE: 3M 7500 half-mask with P3 particulate filters for silica dust during chasing (assigned protection factor 20, compliant with WEL of 0.1 mg/m³). Eye protection: EN 166 rated safety glasses during all cutting and drilling. Hearing protection: 3M Peltor X2A earmuffs (SNR 31) during chasing operations. Gloves: nitrile cut-resistant (EN 388 level 4) for material handling."

Principal contractors and HSE inspectors can tell the difference immediately.

Document what you couldn't verify

If you haven't visited the site, or if information was unavailable, say so:

"Asbestos status: management survey requested from client — not yet received. Risk assessment assumes no asbestos present based on building age (2015 construction). To be reviewed when survey is obtained. If suspect materials are encountered during work, all activities in the affected area will cease immediately."

This is honest and demonstrates competent risk management. Pretending you've verified something you haven't is worse than admitting the gap.

Common site assessment mistakes

Assessing from the car park. Walking into the building and looking at the actual work area reveals hazards that photos and floor plans don't. Overhead services, ground conditions, ventilation, existing damage — these need eyes on.

Ignoring the route to the work area. The hazards don't start at the work face. Carrying materials up three flights of stairs, through narrow corridors, past occupied offices — this is part of the assessment.

Assuming the site won't change. On a multi-week project, conditions change. Other trades start work. Scaffolding goes up or comes down. Temporary services get installed. Your risk assessment needs review triggers, not just a static snapshot.

Forgetting other people's hazards. The roofer's work creates risks for you (falling objects). Your chasing creates risks for the decorator (dust). On multi-trade sites, coordination with the principal contractor is essential — and your risk assessment should show you've considered it.

Copying a previous assessment for a similar project. Two identical job descriptions on two different sites will have different hazards. The 1970s house has potential asbestos. The 2020 new-build doesn't. The ground-floor flat has no height risk. The third-floor flat does. Site-specific means site-specific.

After the site walk

  1. Write the risk assessment while the site is fresh. Don't leave it a week — you'll forget details.
  2. Photograph anything you'll reference. Access routes, the work area, existing services, any pre-existing damage (protect yourself from blame for damage you didn't cause).
  3. Follow up on missing information. Chase the asbestos survey. Request the service drawings. Get the PC's site rules.
  4. Brief your team before they start. The risk assessment is only useful if the people doing the work know what's in it.
  5. Plan your first review point. For a multi-day project, review the assessment after day one — did the reality match your assumptions?

Not sure what documentation your project requires? Our RAMS Requirements Checker helps you identify the full requirements based on your trade and project type.

For the document structure side — how to format and present what you've found — see our risk assessment template guide. If you're producing site-specific risk assessments regularly and want the document produced from your site observations rather than from a template, TradeRAMS is built for exactly that workflow.