CDM Regulations 2015: What Homeowners Need to Know
The Construction (Design and Management) Regulations 2015 apply to construction work in Great Britain, including domestic building projects. This guide explains the main duty-holder roles, when HSE notification is required, and why notification is separate from the appointments and responsibilities that apply to the actual project.
What CDM Regulations Actually Are
The Construction (Design and Management) Regulations 2015, known as CDM 2015, set health and safety duties for people and organisations involved in construction work in Great Britain. They replaced CDM 2007 and include specific provisions for domestic clients.
CDM 2015 is enforced by the Health and Safety Executive (HSE). The regulations place legal duties on everyone involved in a construction project — the client, designers, and contractors. The goal is to ensure that health and safety is considered at every stage, from initial design through to the completed building.
For a homeowner commissioning an extension, loft conversion or refurbishment, the applicable duties depend on the project structure and duty-holder roles. HSE notification is a separate test: a project can be non-notifiable and still be fully subject to CDM duties.
Does CDM Apply to My Project?
CDM 2015 applies to construction work in Great Britain, including domestic projects. There is no general project-size exemption from the Regulations. The duty-holder structure depends on matters including whether the client is domestic or commercial and whether the project involves one contractor or more than one; HSE notification is assessed separately against the statutory thresholds.
CDM Duty Holders and Their Responsibilities
CDM 2015 defines client, designer, contractor, Principal Designer and Principal Contractor duties. Where a project involves more than one contractor, the Principal Designer and Principal Contractor roles must be identified through the CDM framework; domestic-client provisions can transfer specified client duties. TCM's actual role is confirmed for the individual project rather than assumed from this guide.
- For commercial clients, make suitable project arrangements and provide sufficient time and resources
- Where more than one contractor will work on the project, appoint the Principal Designer and Principal Contractor in writing
- Ensure relevant pre-construction information is provided and that a Construction Phase Plan is in place before construction starts
- For domestic clients, specified client duties normally pass to the contractor, Principal Contractor, or a Principal Designer under a written agreement as set out by CDM 2015
- Plan, manage, monitor, and coordinate health and safety during the pre-construction phase
- Identify, eliminate, or control foreseeable risks during design work
- Coordinate designers and the flow of relevant pre-construction information
- Prepare, review, update, and pass on the Health and Safety File where that duty applies
- Plan, manage, monitor, and coordinate health and safety during the construction phase
- Prepare, review, and update the Construction Phase Plan for the construction work under their control
- Organise cooperation between contractors and coordinate construction activities
- Provide appropriate site induction, information, supervision, and welfare arrangements for the construction phase
- Eliminate foreseeable risks so far as reasonably practicable during the design process
- Reduce or control risks that cannot be eliminated
- Provide relevant information about remaining risks to those who need it
- Plan, manage, and monitor their own work so it is carried out without risks to health and safety so far as reasonably practicable
- Ensure workers have the necessary skills, knowledge, training, and supervision for the work
- Cooperate and coordinate with other duty holders where the project involves more than one contractor
When Does a Project Become Notifiable?
Not all projects require formal notification to the HSE. Notification is required when the construction work meets either statutory notification test below. Principal Designer and Principal Contractor appointments are a separate issue: those roles arise on projects involving more than one contractor, whether or not the project is notifiable.
| Trigger | Threshold |
|---|---|
| Duration + workforce | The construction work is scheduled to last longer than 30 working days and have more than 20 workers working simultaneously at any point |
| Person-days | The construction work is scheduled to exceed 500 person-days in total |
| Notification logic | Meeting either notification test makes the project notifiable; CDM duties still apply whether or not a project is notifiable |
Do not infer notification status from the label “extension” or “loft conversion.” Test the actual planned construction duration, maximum number of simultaneous workers and total person-days. For commercial clients, notification is a client duty and submission can be delegated; for domestic projects, the relevant client duties normally pass under CDM regulation 7 to the applicable contractor, Principal Contractor, or Principal Designer under a written agreement.
The Construction Phase Plan
A Construction Phase Plan (CPP) must be prepared before construction begins on any project where CDM applies. The Principal Contractor — or the single contractor where there is only one — is responsible for preparing it.
The CPP does not need to be lengthy for a straightforward domestic project. It must, however, cover the key health and safety arrangements for the site: how the site will be managed, welfare facilities, emergency procedures, and how risks specific to the project will be controlled.
The project documents should identify the contractor or Principal Contractor responsible for preparing and maintaining the Construction Phase Plan. Where TCM holds that role for a particular project, its responsibilities should be stated in the appointment and project records rather than assumed from this page.
The Health and Safety File
On a project involving more than one contractor, the Principal Designer prepares the Health and Safety File. It contains information likely to be needed to protect health and safety during later work on the structure. Commercial-client duties include ensuring the file is prepared and retained; on domestic projects, the relevant client duties normally transfer under CDM regulation 7.
The information included in a Health and Safety File depends on the project and the risks that future work may need to understand. The project team should agree the required handover information rather than rely on a universal domestic-extension checklist. The client should retain the file and make relevant information available when later work on the structure requires it.
How TCM Manages CDM on Your Project
TCM may act as a contractor or, where appropriately appointed and competent for the project, as Principal Contractor. The client, Principal Designer, Principal Contractor, designers and contractors retain the duties attached to their actual roles. Any TCM CDM appointment, documentation responsibility and coordination scope must be confirmed for the individual project; this page does not claim TCM automatically manages every CDM duty.
Required before the construction phase begins; prepared by the contractor or Principal Contractor responsible for the work
Client duty on notifiable projects; submission may be delegated where that responsibility is agreed
The contractor or Principal Contractor organises appropriate cooperation, induction, supervision, welfare and site controls for their scope
Prepared through the Principal Designer route on projects involving more than one contractor and retained by the client
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