The Self Builder & The CDM Regulations (2015)

Health & Safety are at the forefront of construction - building sites are dangerous places.  So, the CDM (Construction Design & Management) Regulations 2015 came into force to emphasise the importance of H&S and make people responsible in law for the health & safety of people working on the site. 


To do this, CDM requires the appointment of a Principal Designer (the person in overall control of the pre-construction phase of the project) and a Principal Contractor (the person in overall control of the construction phase).  Both are legal roles under the regulations


Principal Designer Duties:

  • Manage design decisions
  • Identify and eliminate or control foreseeable risks
  • Ensure co-operation (all parties) during pre-construction phase
  • Assist client with pre-construction information
  • Prepare the Health & Safety file


Principal Contractor Duties:

  • Control over the construction phase
  • Plan the work in liaison with others involved (eg Principal Designer)
  • Identify H&S risks and determine control measures
  • Record details of construction phase plan
  • Liaise with Principal Designer
  • Responsibility for Heath & Safety



Most self builders use someone to do the technical drawings for their new home and to gain planning permission.  They then have nothing to do with that technician and you effectively becomes the Principal Designer making sure the chosen contractor/s know what the new home should be like when finished.  You then need to determine how you get the Principal Contractor duties done.


Larger architectural practices will offer Principal Designer services and prepare everything for the construction phase as well as offering tendering services to find you a suitable contractors.  And there are project management teams available to do all this and oversee the construction phase too. All such things come at a cost.


The following tries to simplify things to allow you to make an informed choice is you have secured planning, but have not engaged that technician to do any more work for you. 


Scenario One


The Self Builder employs a single contractor to carry out construction work, appointing that Contractor as the Principal (Main) Contractor for the duration of the project.


In this case you have no legal duties beyond this appointment


Scenario Two


The Self Builder intends to use more than one contractor so appoints an individual or a business to take on the role of Principal Designer & Principal Contractor


In this case you have no legal duties beyond this appointment



Scenario Three


The Self Builder does it all himself – literally.  No contractors are employed at all and the structure is solely for the you to live in when it is finished.  This is a DIY project because no-one involved is “at work” in the meaning of the Health and Safety at Work etc Act 1974.



Scenario Four


The Self Builder acts as their own Project Manager, employing individual trades at different times.  This is not a DIY project because the self builder is not doing the construction work (although they may become involved).  The self builder is controlling the way in which the construction is carried out, by a person at work, and so must comply with Part 4 of CDM 2015.  This requirement is set out in Regulation 16 of CDM.


Effectively, the self builder is the Principal Contractor in which case, HSE expects demonstration of sufficient health and safety capability to meet Part 4 of CDM 2015.


Individual contractors will be expected to be able to advise the Self Builder on any specialist matters within their own work activities.


HSE’s expectation of a Self Builder in this position will be one of co-ordination and management, not of direct supervision of contractors on site.


The Self Builder is entitled to expect contractors to plan, manage and monitor their own work in compliance with CDM 2015.






Timber Frame - Design & Build Ltd

Holmbush Woods, Stoke Road

Kelly Bray, Callington

PL17 8RA

T: 01579 388800


VAT GB387379534

Company Number 13010500

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