The health and safety file is the last of the three CDM documents — and the one most likely to be forgotten, because by the time it matters the project is finished and everyone has moved on. But it is a legal requirement on most projects, it has a defined owner, and getting it wrong leaves the next project on the same building working blind.
This guide explains what the health and safety file is under the Construction (Design and Management) Regulations 2015, what it must contain, who prepares it, who keeps it, and when it is and is not required. You can also download our free CDM document pack template, which includes a health and safety file starter structure.
What the health and safety file is
The health and safety file is a record of the information that anyone carrying out future construction work on a structure will need to do that work safely. It is not a record of how the original project was managed — that is what the construction phase plan was for. The file looks forward, to the next refurbishment, the next maintenance job, the next demolition.
Think of it from the perspective of a contractor arriving in ten years' time to alter the building. What would they need to know that is not obvious from looking at it? Where the structural load paths are. Where services are buried. What materials were used. How a particular component is safely dismantled. That is the health and safety file.
Who prepares the health and safety file
On projects with more than one contractor, the duty to prepare the file sits with the principal designer. Regulation 12(5) of the Construction (Design and Management) Regulations 2015 (SI 2015/51) states:
"During the pre-construction phase, the principal designer must prepare a health and safety file appropriate to the characteristics of the project which must contain information relating to the project which is likely to be needed during any subsequent project to ensure the health and safety of any person."
Two points follow:
- The principal designer prepares it — not the principal contractor, and not the client. This is one of the clearest ownership rules in CDM 2015.
- It is started during the pre-construction phase, not bolted on at the end. The file is built up as the project progresses, with information added as design and construction decisions are made.
The principal contractor has a supporting role. Regulation 12(7) requires the principal contractor to provide the principal designer with any relevant information in its possession for inclusion in the file — as-built drawings, details of materials used, commissioning records and the like.
What happens if the principal designer leaves early
On many projects the principal designer's appointment ends before the project does. CDM 2015 anticipates this. Regulation 12(8) requires that, where the principal designer's appointment concludes before the end of the project, the principal designer must pass the health and safety file to the principal contractor. From that point Regulation 12(9) makes the principal contractor responsible for reviewing, updating and revising the file through to completion. So the file always has an owner — it never falls into a gap.
What the health and safety file must contain
CDM 2015 does not prescribe a fixed list — the content is whatever is "likely to be needed during any subsequent project," proportionate to the structure. HSE's guidance L153 ("Managing health and safety in construction") sets out the practical contents. A well-built health and safety file typically includes:
1. A description of the work carried out
What was built or altered, and a brief description of the construction methods used where they affect future safety.
2. Residual and significant hazards
The hazards that remain in the completed structure and could not be designed out — for example fragile materials, contaminated land that was capped rather than removed, or a structure that can only be dismantled in a specific sequence. This is the most important section: it tells the next team what to watch for.
3. Key structural principles
The load-bearing elements, safe working loads, and any structural assumptions a future designer must respect before altering the building.
4. Hazardous materials used
Materials present in the structure that future workers must manage — for example specific insulation, sealants or coatings, and their locations.
5. Services information
The location and nature of significant services — electrical, gas, water, drainage, fire systems — particularly anything concealed.
6. Maintenance and cleaning information
Information needed to maintain or clean the structure safely, including safe access for plant, roofs and façades.
7. As-built drawings and equipment manuals
The drawings, plans, and manuals for equipment installed in the structure.
The level of detail is proportionate. A single-storey extension generates a short file; a complex commercial building generates a substantial one. The test, as always under CDM, is whether the next person to work on the structure would have what they need.
What does NOT go in the file
The file is forward-looking, so it should not be padded with project-management paperwork that has no future relevance — pre-construction information, the construction phase plan, risk assessments, method statements, and contractual records all stay out. A health and safety file stuffed with the entire project archive is harder to use, not safer.
Who keeps the health and safety file
When the project is complete, the file is handed to the client, who must keep it available. Regulation 4(5)(b) of CDM 2015 requires the client to ensure that the principal designer prepares a health and safety file that "is kept available for inspection by any person who may need it to comply with any relevant legal requirements."
If the client later sells or otherwise disposes of their interest in the structure, Regulation 4(7) requires them to pass the file to the new owner and make sure that person understands its nature and purpose. The file follows the building — which is the whole point. It is only useful if it is still attached to the structure when the next project starts.
When is a health and safety file required?
A health and safety file is required on any project involving more than one contractor. On a single-contractor project there is no principal designer and no health and safety file requirement — though the contractor still has to manage the work safely under their general duties.
Where a structure already has a health and safety file from previous work, and a new project takes place on it, the file is updated rather than created from scratch — and the relevant parts of it become pre-construction information for the new project. For how that earlier link in the chain works, see our guide to pre-construction information.
How the health and safety file fits the CDM document chain
The health and safety file is the end of one project and the start of the next:
- Pre-construction information sets out what is known before work begins.
- The construction phase plan manages health and safety during the build — see our construction phase plan guide.
- The health and safety file records what the next project will need — and feeds back in as pre-construction information when that next project arrives.
For the full duty-holder map across all three documents, see CDM principal contractor duties.
Bottom line
The health and safety file is prepared by the principal designer (Regulation 12(5)), supported by the principal contractor's information (Regulation 12(7)), handed to and kept available by the client (Regulation 4(5)(b)), and passed on when the building changes hands (Regulation 4(7)). It is required whenever more than one contractor is involved, it looks forward to future work, and it should be lean and useful — not a dumping ground for the project archive.
For a starting structure covering both the health and safety file and pre-construction information, download our free CDM document pack template.
Sources
- CDM 2015 Regulation 12 — construction phase plan and health and safety file (Reg 12(5)-(9))
- CDM 2015 Regulation 4 — client duties (Reg 4(5)(b) and 4(7) on the health and safety file)
- HSE — Managing health and safety in construction (L153)
This guide is for informational purposes and does not constitute legal advice. For project-specific CDM duties, consult your CDM advisor or principal designer. Last reviewed against CDM 2015 (SI 2015/51) on 2026-06-04.