What are the Construction (Design & Management) Regulations (CDM 2015)?

The CDM Regulations (2015) are the main set of regulations for managing the health, safety and welfare of construction projects.

CDM applies to all building and construction work and includes:

  • Extensions
  • Refurbishments
  • New build
  • Demolition
  • Conversions
  • Repairs and maintenance.


Does it apply to me as a homeowner?

The simple answer is Yes! But, you’ll need to read on…

The CDM 2007 guidelines were updated on the 6th April 2015 to bring greater attention to the management of Health and Safety in smaller domestic building sites, shifting more responsibility to the homeowner.


Firstly, let’s discuss the main CDM roles:
  • The Client
  • The Principal Designer
  • The Principal Contractor


There are two types of Client:

Commercial Client – Organisations or individuals for whom a construction project is carried out as part of a business.

Domestic Clients – People who have construction work carried out on their own home (or the home of a family member) that is not as part of a business.

Note: If the householder carries out the work themselves, it is classed as DIY and CDM 2015 does not apply

For the purpose of this article we are focusing on what you need to know as a Domestic Client.

Homeowner = Domestic Client


What do I need to know as the Domestic Client, and what do I do?

The clients’ role is to:

  1. Appoint the right people at the right time
  2. Ensure there are arrangements in place for managing and organising projects
  3. Allow adequate time
  4. Provide information to your designers and contractors

However, the only responsibility a domestic client has under CDM 2015 is to appoint a Principal Designer and Principal Contractor in writing if more than one contractor will be involved. (We’ll define these roles later).

Sound easy? It get’s better…

If you do not do this (as is common practice for small domestic scale building work) your duties as a Domestic Client are automatically transferred to the Contractor or Principal Contractor.


This will depend on how your project is set up (but is normally the case for the type of projects Aura Homes design and manage):

  • If you are employing an Architect and using a main Contractor to build your house extension, conversion, refurbishment or new-build the management of Health, Safety and Welfare on your project is predominantly the Contractors responsibility.
  • When self-managing even one part of the project you will have responsibilities. If you already have a relationship with Aura Homes before the work starts, we can take on your duties, provided there is a written agreement between you and us.


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A useful guide for Clients can be found on the HSE website here and the video below is a great introduction to the CDM Regulations (2015):


Do I need to notify anyone about my building project?

You will also need to notify the Health and Safety Executive (HSE) using an F10 form before commencing construction IF your work is scheduled to:

  • Last longer than 30 working days AND
  • Have more than 20 workers working simultaneously at any point in the project


  • Exceeds 500 person days

HSE person days examples

In our experience projects with a construction value below £200,000 (ex. VAT) seldom fall in to the above description.

Useful Tip!… If you’re looking to get an idea of how much your building project may cost, see our useful article: How much will my house extension cost?


What is a Principal Designer and what do they do?

“Designers appointed by the client in projects involving more than one contractor. They can be an organisation or an individual with sufficient knowledge, experience and ability to carry out the role.”

So the Principal Designer is my Architect?

Not exactly….

Company’s like Aura Homes can perform these services but by Law there will need to be a written appointment to say that we are providing these services on your behalf.

The Principal Designer roles are to:

  1. Plan, manage, monitor and coordinate health and safety in the pre-construction phase of a project. This includes:
    • identifying, eliminating or controlling foreseeable risks
    • ensuring designers carry out their duties, communicate and coordinate with others (these other ‘designers’ could be structural engineers, heating and ventilation engineers or landscape architects for example.)
      • Designer Definition: Organisations or individuals who as part of a business, prepare or modify designs for a building, product or system relating to construction work.
  2. Prepare and provide relevant pre-construction information (such as drawings, schedules and specifications) to other dutyholders
  3. Liaise with the Principal Contractor to help in the planning, management, monitoring and coordination of the construction phase.
  4. Preparation of the Health and Safety File – Read more further in this article

Note: Where the appointment of the Principal Designer concludes before the end of the project the responsibility for preparation of the Health and Safety File, and subsequent handover to the Client, will pass onto the Principal Contractor. This frequently happens on smaller projects and where your Principal Designer (e.g. Architect) are not employed to carry out site monitoring during the building works.


What is a Principal Contractor?

“A Contractor appointed by the client to coordinate the construction phase of a project where it involves more than one contractor or trade”

Put simply…

For house extensions, conversions, refurbishments and new-build houses the construction work carried out will involve many building trades such as bricklayers, carpenters, plumbers, electricians…the list goes on. The contractor coordinating these trades should be the Principal Contractor.

The role of the Principal Contractor is to:

  1. Plan, manage, monitor and coordinate health and safety in the construction phase of a project. This includes:
    • liaising with the client and principal designer to share relevant information
    • preparing the written Construction Phase Plan before works commence, and implement, review, and update the plan during the works – read more about the CPP further in this article.
    • organising cooperation between contractors and coordinating their work to reduce health and safety risks to everyone affected (including the public)
  2. Make sure:
    • suitable site inductions are provided to workers
    • everyone they appoint has the skills, knowledge and experience to carry out their work safely
    • reasonable steps are taken to prevent unauthorised access to site
    • workers are consulted and engaged in securing their health and safety
    • welfare facilities are provided throughout the project



“Organisations or individuals can carry out the role of more than one dutyholder, provided they have the skills, knowledge, experience and (if an organisation) the organisational capability necessary to carry out those roles in a way that secures health and safety.”

In this scenario a loft conversion specialist providing ‘Design and Build’ services for example, may be both the Principal Designer and the Principal Contractor.

Lets break this down in to simple steps….

3 step CDM image3 step CDM image 2 3 step CDM image 3


The Construction Industry Training Board (CITB) and Health and Safety Executive (HSE) websites are an excellent source for further information:

CITB logo

HSE logo


What is a Health and Safety File?

A record of relevant health and safety information relating to the completed building works so that subsequent repair, maintenance and other building works can be carried out safely with known risks. The file should be “appropriate to the characteristics of the project”.

The following information should be included in the Health and Safety File:

  1. A brief description of the work being carried out
  2. Hazards that have not been eliminated through the design and construction phases and how these have been addressed
  3. Background information on the structural design and form of the building including any limitations – safe working loads for floors and roofs
  4. The location of key utility services i.e. gas supply, underground cables, and fire-detection systems
  5. Notes on any hazardous materials used (paints and coatings for example)
  6. Information, including drawings of the building as built. This should contain information on safe means of access, fire strategies, and relevant plant/machinery.

The Health and Safety File should only contain information that would be relevant when planning FUTURE construction works. The file can be delivered in electronic format.


What is a Construction Phase Plan?

It is the Principal Contractors responsibility to plan and organise your building project, and work together with others involved to make sure that the work is carried out without risks to health and safety. The Construction Phase Plan is a record of how they will do this.

The plan should contain:

  • Key project dates
  • Relevant information from the client e.g. utility service locations and isolation points, access restrictions, whether there is any asbestos present
  • Record details of anybody else working on the job and detail site rules and health and safety information
  • Explain how the communication channels will work including who to report to and who will be making key decisions
  • Information on the main dangers on site and how they will be controlled i.e. working at height, structure collapse, exposure to asbestos
  • Details on the toilet, washing and rest facilities


Download an example HSE Construction Phase Plan template for your builder here


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Ben Richards
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