L153 is HSE's official guidance on the Construction (Design and Management) Regulations 2015. Its full title is Managing health and safety in construction: Construction (Design and Management) Regulations 2015. Guidance on Regulations, published in 2015 (ISBN 9780717666263) and available as a free download from HSE.
The detail that most summaries get wrong: L153 is not an Approved Code of Practice. HSE publishes it as "Guidance on Regulations" — that is the subtitle on its own cover, and the description carried against L153 in HSE's current legal-series index, which lists other titles (L8, L22, L24, L103, L104, L148) explicitly as Approved Codes of Practice. That index lists no Approved Code of Practice for CDM 2015. That is not pedantry — it changes what L153 does to you in a prosecution.
ACOP versus guidance, and why the difference is real
An Approved Code of Practice has a specific statutory status under section 17 of the Health and Safety at Work etc. Act 1974. In broad terms, if you are prosecuted for breaching a requirement that an ACOP covers and you did not follow the ACOP, the court must find you failed to comply unless you can show you satisfied the requirement some other way. The ACOP effectively reverses the practical burden.
Guidance carries no such provision. Following L153 is strong evidence that you have acted reasonably; departing from it is not automatically a breach, and HSE has to prove the underlying regulation was contravened on its own terms.
The practical consequence for a principal contractor is smaller than it sounds, and the reason matters. CDM 2015's duties are mostly written as "must plan, manage and monitor... so far as is reasonably practicable." When the standard is reasonable practicability, the regulator's published view of what is reasonable is what an inspector will measure you against, whether or not it carries ACOP status. So L153 remains the practical benchmark. It just is not a legal shortcut in either direction.
Where the distinction genuinely bites: do not cite L153 as though it creates a duty. It does not. Duties come from the Regulations. L153 explains them. A method statement or policy that says "L153 requires X" is citing the wrong instrument — the correct form is "Regulation 15(2) requires X; L153 explains what that looks like in practice."
What L153 actually covers
HSE describes L153 as describing "the law that applies to the whole construction process on all construction projects, from concept to completion" and setting out "what each dutyholder must or should do to comply with the law."
That "must or should" split is the most useful thing in the document — but it does not mean what most people assume, and L153's own glossary is explicit about it:
- "Must" — "'must' is used only where there is an absolute duty, ie an explicit legal requirement to take a certain action which is not qualified by terms such as 'so far as reasonably practicable'."
- "Should" — "'should' is used to indicate what to do to comply with legal requirements which are qualified by terms such as 'so far as reasonably practicable'."
Read that carefully, because the common reading of it is wrong. "Should" in L153 is not a synonym for optional or good practice. Both words point at legal requirements. The difference is whether the underlying duty in the Regulations is absolute or qualified by reasonable practicability. A "should" is still something you have to do unless doing it would be grossly disproportionate to the risk — and if you depart from it you need to be able to say why, on those terms.
If you are trying to work out how hard a requirement bites, that single word is usually the answer. What it never means is that the requirement is discretionary.
L153 works through the duty holders in turn — clients, principal designers, designers, principal contractors, contractors and workers — and then through the project documents: pre-construction information, the construction phase plan, and the health and safety file.
How to use it in practice
As the interpretation layer, not the source. Read the regulation first, then L153's explanation of it. If you only read L153 you will absorb HSE's recommended approach without knowing which parts are the actual duty. Cite the regulation; use L153 to justify how you chose to meet it.
For proportionality. The most common CDM failure is not omission but over-application — hundred-page construction phase plans on two-week refurbishments. L153 is explicit that arrangements should be proportionate to the project's risks, and it is the document to point at when a client's template demands more than the job warrants.
As the shared reference in a disagreement. When a client, a principal designer and a principal contractor disagree about who owes what, L153's duty-holder chapters usually settle it faster than arguing from the Regulations alone, because they address the overlaps directly.
Not as a checklist. L153 is not structured as one and using it that way produces exactly the box-ticking CDM 2015 was rewritten to move away from.
What L153 does not do
- It does not create duties. Every obligation traces to the Regulations.
- It does not cover everything on a construction site. Work at height, COSHH, lifting operations, asbestos and noise each have their own regulations and their own guidance. L153 addresses the CDM framework around them.
- It has not been reissued for the Building Safety Act 2022. Higher-risk building duties, the gateway regime and the Building Safety Regulator sit outside L153, and you need the separate BSR guidance for those.
- It is not a substitute for competent advice on a specific project.
- It does not cover Northern Ireland. Regulation 3 of CDM 2015 applies the Regulations "in Great Britain". NI construction work is governed by the Construction (Design and Management) Regulations (Northern Ireland) 2016, in operation since 1 August 2016. L153 is guidance on the GB Regulations and does not address the NI instrument.
Where the confusion comes from
Two things. First, CDM 2007 did have an ACOP, and it was withdrawn. L153 says so itself, in its opening paragraph: CDM 2015 replaces CDM 2007 from 6 April 2015, and "[f]rom this date, the Approved Code of Practice (ACOP) which provides supporting guidance on CDM 2007 is withdrawn" (L153, Introduction, "About this book", para 1). A great deal of secondary content was written during the transition and never corrected, so "the CDM ACOP" persists in circulation. Secondary sources also still attach a specific L-series code to that withdrawn document; HSE no longer publishes a page for it, so treat any such code you are given as unverified rather than repeating it.
Second, HSE's L-series contains both ACOPs and guidance under the same series prefix. L8 (legionella) is an ACOP and guidance combined; L153 is guidance only. The series code tells you nothing about status — the subtitle does. If a document's cover says "Guidance on Regulations", it is not an ACOP.
If you have policies, RAMS templates or tender documents that cite "the CDM Approved Code of Practice", they are pointing at the withdrawn CDM 2007 code, not at anything currently in force for CDM 2015. Worth a find-and-replace.
The short version
L153 is the document to work from, but for the right reason. It is HSE's own account of what CDM 2015 requires and how to satisfy it proportionately — authoritative, free, and the benchmark an inspector will use. It simply is not an Approved Code of Practice, it creates no duties of its own, and citing it as the source of a legal obligation is a small error that undermines an otherwise sound document.
For the regulations themselves, see our CDM 2015 regulations summary. For the duty-holder map L153 works through, see CDM duty holders explained. For the three project documents it covers, see our guides to pre-construction information, the construction phase plan, and the health and safety file.
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Sources
- HSE L153 — Managing health and safety in construction: CDM 2015. Guidance on Regulations (free PDF)
- HSE — Legal series (L) publications index
- The Construction (Design and Management) Regulations 2015 (SI 2015/51), Regulation 3 (application in Great Britain)
- The Construction (Design and Management) Regulations (Northern Ireland) 2016 (SR 2016/146)
- The Construction (Design and Management) Regulations 2015 (SI 2015/51)
- Health and Safety at Work etc. Act 1974, section 17
This guide is for informational purposes and does not constitute legal advice. For project-specific CDM compliance questions, consult a qualified health and safety professional.
Last reviewed: 7 October 2026