A confined space risk assessment under the Confined Spaces Regulations 1997 is one of the most heavily scrutinised documents in UK construction. It carries a specific statutory duty to identify the specified risks (fire / explosion, loss of consciousness from heat, gas / fumes / vapour, drowning, asphyxiation, free-flowing solids) and to demonstrate that entry is genuinely necessary. Reviewers reject these documents quickly when the 'avoid entry' option has not been seriously considered.
Regulation 1(2) of the Confined Spaces Regulations 1997 defines a confined space by two tests: (a) it is substantially enclosed (though not necessarily entirely enclosed), and (b) one or more of the specified risks is reasonably foreseeable inside it. Both tests have to be met. A room is not a confined space simply because it is small — it has to carry the specified risk profile.
This matters for the assessment because the document must open with the determination: is this space a confined space under the 1997 Regulations? Tanks, sewers, ducts, silos, vaults, vessels, manholes, deep excavations and parts of plant are all common entries. Crawl spaces and roof voids only qualify if a specified risk is present.
Regulation 4(1) imposes an explicit duty to ensure that, so far as is reasonably practicable, no person enters a confined space to carry out work for any purpose unless it is not reasonably practicable to achieve that purpose without such entry. In other words, the document has to show that remote inspection (camera, CCTV crawler, sonar), external repair, or design change have been considered first. A risk assessment that goes straight to PPE and gas testing without addressing the avoid-entry duty is non-compliant on its face.
This is the section that catches most contractors. Reviewers expect a short, honest paragraph: we considered X, Y and Z; here is why entry remains necessary.
Regulation 4(2) requires a safe system of work. For most confined spaces this means atmospheric testing before entry (oxygen, flammable gas / vapour, carbon monoxide, hydrogen sulphide as a minimum) and continuous monitoring during the work. The assessment has to name the gas detector, the alarm set-points (typically 19.5% O2 low, 23.5% O2 high, 10% LEL, 35 ppm CO, 5 ppm H2S) and the calibration / bump-test regime.
For sewer and drainage work the assessment also references the Sewerage Sector Guidance (SSG) and the WRc Sewers for Adoption testing protocols. For chambers in industrial settings, the assessment names the lock-out / tag-out procedure that isolates incoming pipework before entry.
Regulation 5 requires that suitable and sufficient arrangements for the rescue of persons have been made before any person enters the space. This is the spine of the assessment. The document names the top-man (who stays outside, in constant communication, never enters under any circumstances), the rescue equipment on site (tripod, winch, rescue harness, resuscitation equipment), the trained rescue team (or the agreement with the fire and rescue service), and the maximum time from collapse to rescue.
HSE INDG258 is the standard reference for the rescue regime; the assessment should cite it and demonstrate compliance.
The numbered sections a reviewer expects to see, in order.
Apply the regulation 1(2) two-part test and record the conclusion in writing.
Document why entry is necessary — what alternatives were considered and rejected.
Identify which of the six specified risks (fire / consciousness / gas / drowning / asphyxiation / free-flowing solids) apply.
Gas detector model, calibration regime, alarm set-points, pre-entry and continuous monitoring procedure.
Step-by-step entry sequence, isolation procedure, communication method, work duration limit.
Top-man, rescue equipment on site, named trained rescuers, resuscitation equipment, maximum rescue time.
Self-contained breathing apparatus or escape sets — model, RPE face-fit records, inspection dates.
Cross-reference to the entry permit that authorises the work and records sign-on / sign-off.
Names of entrants, top-man and rescuers with their City & Guilds 6160 or equivalent confined space training certificates.
Why a risk assessment gets sent back — these are the patterns we see most often.
The legal framework this risk assessment operates inside. Links go to the official source.
SI 1997/1713
The primary statutory framework — avoid-entry duty, safe system, rescue duty.
HSE L101
Approved Code of Practice for the 1997 Regulations — the benchmark reviewers use.
HSE INDG258
Plain-English summary; sets the standard for the rescue regime referenced in most assessments.
SI 2015/51
Imposes the principal contractor's duty to plan and monitor work — including confined space entry.
Only if a specified risk is reasonably foreseeable inside it. A typical domestic loft is not in scope. A commercial roof void with insulation off-gassing, residual asbestos, or a sealed plant chamber with potential gas accumulation may be — the test is the risk profile, not the geometry.
No. The top-man stays outside, maintains communication, and never enters the space under any circumstances — entering to attempt a rescue is the most common cause of multi-fatality confined space incidents in UK statistics. The rescuer is a separate, trained operative on site (or, where the system of work allows, the dedicated rescue team arranged in advance).
In practice yes for most confined spaces. The risk assessment establishes the system of work; the permit authorises a specific entry under that system, records the gas test results at entry time, and provides the sign-on / sign-off audit trail. Most principal contractors will not accept a confined space entry without both documents.
The 1997 Regulations don't specify a make or model — they require a system of work that controls atmospheric risk. In practice that means a 4-gas detector (O2, LEL, CO, H2S) at minimum, bump-tested before each shift, full calibration within the manufacturer's interval (commonly 6 months), with a documented calibration record.
Yes where the excavation meets the regulation 1(2) test — typically deep excavations with potential gas ingress from contaminated ground, sewer connections, or asphyxiating gases from soil bacteria. A simple open trench in clean ground is not in scope; a deep chamber excavation adjacent to a live sewer almost always is.
Trade-specific RAMS guidance for the contractors who typically produce this risk assessment.
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Final RAMS must be reviewed and approved by a competent person before use.