The Health and Safety File: what it must contain, and who's actually responsible for it

Under CDM 2015, the principal designer is responsible for preparing a health and safety file for the project — a document that's easy to underrate because its value is almost entirely deferred. It doesn't help anyone this week. It's meant to help whoever needs to alter, maintain or demolish the building years, sometimes decades, after the project that produced it has finished and everyone involved has moved on.

What it's actually for

The file exists to answer a specific, recurring question: what does someone carrying out future construction work on this building need to know to do it safely? That framing matters, because it means the file isn't a general project archive — drawings, correspondence, contracts — but a filtered set of information specifically relevant to health and safety in future work. A file that's really just a dumping ground for everything the design team produced isn't doing its job any better than one that's too thin; the value is in the filtering, not the volume.

What actually goes in it

• –As-built drawings and details showing what was actually constructed, not just what was originally designed, where the two diverge
• –Residual hazards left in the structure and how they've been dealt with — hazardous materials still present, structural features that limit safe alteration, and similar
• –Key structural principles the designer has assumed, particularly anything that limits later loading, drilling or removal of elements without a further check
• –The location and details of significant services concealed in the structure or ground — cabling, pipework, drainage runs that aren't visible from a casual inspection
• –Information on equipment and maintenance facilities needed to maintain the structure safely, such as fixed access points for future window cleaning or roof maintenance
• –Any nature of remaining hazards and how they've been controlled, including information relevant to demolition should that ever be needed

Who prepares it, and when

The duty sits with the principal designer, and the important detail people often miss is the timing — the file should be started during the pre-construction phase and built up progressively as the project develops, not assembled retrospectively in the final weeks before handover. A principal designer collating years of design decisions from memory after the fact produces a noticeably weaker file than one who's been logging health-and-safety-relevant information as it emerges, because the person best placed to judge what's genuinely relevant is the one who was there when the decision was made, not someone reconstructing it later.

Smaller projects, and who holds the duty then

Not every project has a principal designer in the way a larger, multi-contractor scheme does. On a project with only one contractor, the duty to prepare — or in practice often update — a health and safety file still exists, but it typically falls to whoever's acting as designer or contractor rather than a formally appointed principal designer role. This is one more example of why getting the duty-holder roles genuinely clear at the outset of a project matters beyond the construction phase itself — a project that never establishes who's responsible for the file is quite likely to finish without a usable one existing at all.

Where the file frequently falls short

A common failure mode isn't that no file gets produced — it's that a file exists but is written at a level of generality that doesn't actually help anyone. A note that says "services present in the ground floor slab, exercise caution" tells a future contractor almost nothing useful; a note that gives an approximate location, depth and type of service, referencing an as-built drawing, actually lets them plan safely. The difference between these two versions of the same underlying information is the difference between a file that satisfies the letter of the requirement and one that satisfies its actual purpose.

A worked example

Take a commercial fit-out from several years ago that used a small quantity of asbestos-containing material in an area that was subsequently boxed in rather than removed, because removal wasn't reasonably practicable at the time and the material was left in good condition and clearly recorded. A contractor coming in years later to strip that area for a new tenant fit-out has no way of knowing this unless the health and safety file tells them — there's nothing visually distinct about a boxed-in wall that contains ACMs versus one that doesn't. A properly maintained file, handed to that contractor before work starts, is what stands between a controlled, planned removal and someone unknowingly disturbing the material with a stripping-out crew who had no idea it was there.

Handover, and who's meant to hold onto it afterwards

The file is handed to the client at the end of the construction phase, and the client is then responsible for keeping it available and passing it on to whoever needs it for future work — a subsequent owner if the building is sold, or a contractor appointed for a later project. This is a genuine weak point in practice: the file's usefulness depends entirely on it actually surviving between projects, sometimes across a change of building ownership, sometimes across a gap of many years with no construction activity at all in between. A client who treats the file as just another folder from the original build, filed away and forgotten, is undermining the entire point of having required it in the first place.

Updating it for later work, rather than starting again

When further construction work happens on the building — an extension, a refurbishment, a partial demolition — the file should be reviewed and updated to reflect what's changed, not treated as a closed historical document that gets superseded by a new one. In practice this means whoever's acting as principal designer on that later project has a duty to review the existing file, incorporate genuinely new information, and hand back an updated version — which only works smoothly if the original file was handed over and located at the start of that later project, rather than turning up as an afterthought once work is already underway.

Digital files and version control

Increasingly the file exists as a digital record rather than a physical folder, which solves some of the survival problem but introduces a version-control one — if a building has been through several rounds of work, each producing an updated file, it needs to be genuinely clear which version is current and where superseded information has been correctly carried forward rather than lost in the transition between formats or software. A digital file that's easy to find but hasn't actually been kept current is not meaningfully better than a paper one gathering dust in a site office drawer.

Why this connects back to the construction phase plan

It's worth being clear about how the health and safety file relates to the project's construction phase plan, because the two are easy to conflate. The construction phase plan governs safety during the current construction work and is largely irrelevant once the project finishes. The health and safety file is the opposite — it has almost no relevance during the construction phase itself and exists entirely for whoever comes afterwards. A principal contractor focused on running today's site safely can reasonably treat the file as the principal designer's responsibility, but it's worth flagging anything discovered during construction — an unexpected service, a hazardous material found where none was anticipated — back to the principal designer so it actually makes it into the file, rather than assuming someone else will have already captured it.

Common mistakes

• –Leaving the file to be assembled retrospectively at project close-out, rather than built up as decisions are made
• –Writing entries too generally to be genuinely useful to someone reading the file years later with no other context
• –Treating the file as complete once handed over, rather than something that gets updated when further work happens
• –The client losing track of the file over time, particularly across a change of building ownership
• –Not flagging site discoveries made during construction back to whoever's responsible for updating the file
• –Confusing the health and safety file with the construction phase plan, which serve entirely different purposes at different points in a project's life