22nd September, 2021

Does CDM Apply To Site Investigations?

A common question regarding CDM is, do the regulations apply to site investigations? In this post, we look at the definition of construction work under CDM 2015 and consider how these regulations apply to site investigation work.

Does CDM Apply To Site Investigations? header image

The Construction (Design and Management) Regulations 2015 (aka CDM 2015) apply to all construction work in Great Britain. That includes new builds, refurbishments, demolition, painting, even maintenance.

The definition of construction work under CDM is far-reaching. If you are doing construction work of any kind, then CDM applies.

But what about planning for construction work or just thinking about construction work. What if you are checking if the site is suitable for structure. Or if you are gathering information on the site. Or if you look into a specific issue on a site.

Often site investigation might not be considered construction work. After all, you are not building anything. Not at that specific time anyway. And the work does not involve altering a structure either.

It may surprise you then to know that the regulations do class site investigation as construction work, under part b of the definition.

(b) the preparation for an intended structure, including site clearance, exploration, investigation (but not site survey) and excavation (but not pre-construction archaeological investigations), and the clearance or preparation of the site or structure for use or occupation at its conclusion;

The Construction (Design and Management) Regulations 2015 Interpretation

Note that there are some exceptions. Not every site investigation is considered construction work under CDM.

Site investigation gets classed as construction work when is it part of the preparation for an intended structure. So if you are conducting or organising a site investigation to gather information for a future building project, CDM will apply.

And this intended structure does not just mean a building. The definition of a structure under CDM includes anything from pipes and earthworks to roads, railways and buildings. And plenty of other things too. It's probably best for us to quote the full definition here so that you don't miss anything!

"structure" means—

  1. any building, timber, masonry, metal or reinforced concrete structure, railway line or siding, tramway line, dock, harbour, inland navigation, tunnel, shaft, bridge, viaduct, waterworks, reservoir, pipe or pipeline, cable, aqueduct, sewer, sewage works, gasholder, road, airfield, sea defence works, river works, drainage works, earthworks, lagoon, dam, wall, caisson, mast, tower, pylon, underground tank, earth retaining structure or structure designed to preserve or alter any natural feature and fixed plant;
  2. any structure similar to anything specified in paragraph (a);
  3. any formwork, falsework, scaffold or other structure designed or used to provide support or means of access during construction work,

and any reference to a structure includes part of a structure;

The Construction (Design and Management) Regulations 2015 Interpretation

So if you are doing a site investigation in preparation for any of the types of structures listed above, then CDM applies.

Going back to where site investigations are in the definition of construction work under CDM...

(b) the preparation for an intended structure, including site clearance, exploration, investigation (but not site survey) and excavation (but not pre-construction archaeological investigations), and the clearance or preparation of the site or structure for use or occupation at its conclusion;

The Construction (Design and Management) Regulations 2015 Interpretation

Notice how site clearance, exploration and investigations ARE included, but site surveys are NOT included.

You need to determine if you are doing a site survey or an investigation. Anything intrusive is likely to fall under the category of site investigation, rather than a survey. But of course, it doesn’t help that the terms site investigation, site survey and ground investigation are often confused or interpreted differently from project to project.

If you are about to do a site investigation, how do you know if your work falls under CDM? After all, you need to make sure you apply the additional legal duties required. You might need to appoint CDM dutyholders or create CDM documents.

Like with many things in health and safety, it is best to take a common-sense approach. If you know that the site investigation is or future building work or groundwork, then CDM will apply. If it is part of a larger construction project, then CDM will apply.

But you can also take a proportionate approach. If CDM applies but the project is simple, then the CDM requirements are also likely to be straightforward.

CDM is about following good health and safety practices, including communicating, cooperating and being aware of potential hazards. Be prepared for hidden dangers like ground contamination, flooding, confined spaces and underground services. And remember, even if CDM doesn't apply to your work, other health and safety legislation still applies to all work activities. You need to identify the hazards and control the risks.


If you are unsure about your legal duties under CDM, check out our free CDM duty holder guides, or get started with the free CDM compliance checklist. You can also find hundreds of health and safety document templates to use on your projects.

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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