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CDM Regulations 2015 | Comprehensive Guide

construction workers performing an excavation

The UK Construction (Design and Management) Regulations 2015 (CDM 2015) set legal requirements for safe construction work. They define roles and responsibilities for all parties, including clients, designers, and contractors, to ensure health and safety throughout the project.


What are the CDM Regulations 2015?


The CDM Regulations 2015 cover Construction (Design and Management) and it provide the regulations for all construction projects and how to manage the health, safety and welfare of everyone involved.

These regulations apply to all construction work including complete new builds, refurbishments, demolition, conversions, extensions and maintenance and repair.

The regulations created by the Health and Safety Executive (HSE) ensure that there is sufficient planning carried out for all construction work and provides guidelines to help keep everyone safe during the construction. The CDM regulations have been updated over the years and its main focus is to prevent accidents and fatalities during construction work by regularly identifying and managing risks.


What is Notifiable Under the CDM Regulations?


It is a legal requirement that some construction projects are notified to the HSE to ensure they know about the work taking place and when. The HSE states that a project is Notifiable when the “project lasts longer than 30 days and has more than 20 people working simultaneously at any point in the project or if it exceeds 500 person days.”

This means that if your project has less than 20 workers, the 30 day legislation won’t apply to you but it doesn’t necessarily mean you don’t have to notify HSE. If you exceed the 500 person days then you still have to notify the HSE, for example if you have 10 workers that work over 50 days.

It is essential that you calculate the amount of days or people the construction project will require as the HSE must be notified of any construction work that fits the rules before any work actually starts.



What is the Purpose of the CDM Regulations?


The purpose of the CDM Regulations is to ensure there is a sufficient plan created and followed through and that all duty holders understand their roles during the construction phase.

The CDM is designed to secure the health and safety of all workers in the construction industry by providing guidance which includes:

  • Correctly and sensibly plan the construction work to prevent and manage risks throughout.

  • Ensure the right people are used for the job at the right time.

  • Ensure all duty holders cooperate and coordinate the construction work with other teams.

  • Ensure everyone has received the correct information and understand the risks and how they are being controlled.

  • Ensure communication of all required information is given to the right people.

  • Consult all workers on the risks and how to ensure the health and safety of workers.



2 construction managers reviewing a document

Who Do the CDM Regulations Apply To?


The CDM regulations establish the roles of 7 duty holders required during the construction work that takes place.

It is possible that individuals can take on the role of more than one duty holder as long as they are fully trained and have the knowledge, skills and experience to ensure the roles are carried out to maintain health and safety.

The duty holder roles include:

Commercial Clients

This is the individuals or organisations in which a construction project is done as part of a business. These duty holders must manage the construction by appointing other duty holders and allocating sufficient time and resources for the job. They will ensure everyone carries out their roles and has received the necessary information and welfare facilities are provided.

Domestic Clients

Those who have work performed in their home that is not part of a business (if the house owner does the work, this is DIY and CDM doesn’t apply). These duties are often transferred to the contractor or principal contractor.


Those who prepare and design the construction work for buildings or systems. They must eliminate or control any risks that may appear during construction or the maintenance once it is built and provide other duty holders with relevant information to enable them to fulfil their duties.

Principal Designers

These are the designers appointed by the client during projects with multiple contractors. They will plan, monitor and manage the health and safety during construction and assess the risks and ensure the designers complete their duties.

Principal Contractors

Contractors appointed by the client when there are multiple contractors for one project. They will liaise with the client and principal designer, prepare the construction plan and organise contractors working together to ensure health and safety.


These carry out the construction work. They will plan and manage the construction ensuring health and safety and coordinate their plans with the other teams when required.


These are the employees working for the site or the contractors. They must be consulted over health and safety matters, take care of themselves and other during construction and report any issues that may affect health and safety.



4 construction worker reviewing cdm documents

The 4 Main forms Under CDM 2015


The CDM regulations 2015 require 4 main documents to be completed for construction projects. It is vital that you know when to use them and who is responsible for producing them.



This is the form that notifies the HSE of your construction project and must be completed if your project is notifiable due to the rules.

The HSE states that:

  • Commercial clients must notify HSE

  • Notification must be carried out on behalf of the domestic client by the:

  • Contractor (or principal contractor if more than one)

  • Principal designer where there’s a written agreement to carry out the client's duties.

Once the notification has been submitted online clients are provided with a unique serial number to access and edit the submission.


Pre-Construction Information


The pre construction information must be completed before the project starts and is required for all projects no matter how big or small. The client must produce this information which is then given to the contractors and designers who are planning the work to ensure the work is carried out safely. This will inform the contractors and designers of any hazards on site and if there are any risks which may affect the design and construction.

If there is a principal designer involved, they will also help the client to put this information together. It will include information on the project, arrangements and health and safety and should also include surveys and plans previously performed.



The construction phase plan is also required for every construction project and is the responsibility of the principal contractor unless there is only one contractor involved who then must be responsible. This plan must be completed before any work begins and will highlight all the hazards on site and explain the measures implemented to manage the workers health and safety throughout the whole construction process.

However, the plans may change and be improved during the construction as new issues are found and changes are required in which the plan can be revised and added to, to ensure all changes are recorded.


Health and Safety File


The health and safety file is required for construction projects that use more than one contractor and is produced by the principal designer and given to the client once the construction project has been completed. The form contains the essential health and safety information regarding the construction’s maintenance and cleaning for future use.

The file is started during the pre construction phase and will be developed throughout the project to ensure all information is noted for the client to maintain the health and safety of the construction. The principal contractor and the other contractors and designers will provide relevant information regarding their work to be included in the file.


Updates to the CDM Regulations


The CDM Regulations were first introduced in the UK in 1994 and the regulations are regularly updated to provide the most relevant duties and information for all construction projects to maintain the health and safety of everyone throughout the process.

These are the CDM updates:

CDM 1994

 The CDM 1994 was the first version of the regulations which created the roles of principal contractor and planning supervisor. This was also when the regulations only applied to notifiable construction projects to the HSE which had to be done by post or fax as there was no online service yet available.

The 1994 regulations also introduced roles and responsibilities which focused more on the contractors and the project team than the clients. It also introduced the health and safety plan which is now known as the pre construction phase plan.


CDM 2007

 The 2007 updates to the CDM regulations include welfare requirements which combine with the previous Construction (Health Safety and Welfare) Regulations under CDM. The planning supervisor role has now been removed and is replaced with the CDM Coordinator with similar roles and is used to give advice and assistance to clients.

The CDM regulations now apply to all construction projects and not just notifiable ones with the exception of domestic projects. More responsibilities are placed on the clients and it also introduced the pre construction information and changes the name of the health and safety plan to the construction phase plan.


CDM 2015

 The CDM 2015 regulations remove the CDM coordinator and introduce the principal designer. Even more responsibilities are placed on the client which includes notification to the HSE and the arrangement of an appropriate project team. The principal designer is responsible for the planning stages and the health and safety until the start of the project when the responsibility is then placed on the principal contractor. Domestic construction projects are now also included in the CDM regulations.


CDM 2023

 The latest update to the CDM regulations in 2023 stated that all duty holders will receive additional duties which involve the planning, managing and monitoring of all activities which now apply to all buildings and not just those of higher risk. The duty holders are required to maintain all of the duties stated in the previous regulations.



4 construction workers pouring a concrete slab

Topics Covered under CDM Regulations 2015


Safe Access to Site


The HSE states that there must be suitable and safe access to and from all construction sites to any other place provided for workers and every place that the construction is being carried out. Construction sites must be kept safe without risks to ensure the health and safety of all workers and action must be taken to ensure no workers use access to the site which doesn’t comply with the regulations.


Inspection of Supported Excavation


The legislation states that steps must be taken to avoid danger to any persons to ensure no excavation collapses, falls or traps a worker. Suitable steps must also be taken to prevent any workers or work equipment from falling into the excavation.

The construction work mustn’t be carried out unless the excavation and any work equipment has been inspected by a competent person prior to the work, after an event may have affected the stability or when any material has fallen or been dislodged. Construction work mustn’t be carried out until the competent person deems the inspection satisfactory.


How Long to Keep Inspection Records


The HSE also states that once an inspection has been carried out, a copy of the report must be kept to ensure it is available for inspection by an inspector of the Executive at the site of the inspection for 3 months after the completion of the construction work with the ability to send the inspector extracts or copies of the report if and when required.


Notifying HSE of a Non-Domestic Project


The HSE states that it must be notified of a non-domestic project if the work lasts longer than 30 working days and have more than 20 workers working simultaneously at any point in the project or if it exceeds 500 person days. The client must then notify the Executive prior to the construction phase.



CDM Applications in the Rail Sector


The CDM Regulations ensures that all railway construction provides the right information to the right people at the right time and there is an established chain of responsibility throughout a change to the railway. They must eliminate the risks and dangers and manage them away from the public and passengers.





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