Do I Need CDM Notification?

When Is Notification Required?

Under Regulation 6 of the CDM Regulations 2015, the client must notify the HSE if the construction work on a project is expected to:

• Last longer than 30 working days and have more than 20 workers working simultaneously at any point, OR
• Exceed 500 person days in total

How to Notify

• Submit an F10 form to the HSE (online at hse.gov.uk)
• Must be submitted before construction begins
• Include project details, client, designer, principal contractor
• A copy must be displayed on the site notice board

CDM Applies to All Construction Projects

Even if notification is not required, CDM 2015 still applies to all construction work in Great Britain. The key duties are:

• Client: Make suitable arrangements for managing the project
• Designer: Eliminate or reduce risks through design
• Principal designer: Plan, manage, and coordinate pre-construction (notifiable projects)
• Principal contractor: Plan, manage, and coordinate the construction phase (notifiable projects)
• Contractors/workers: Plan, manage, and carry out work safely

Domestic Clients

Domestic clients (homeowners commissioning work on their own home) have CDM duties, but these are normally transferred to the contractor or principal contractor automatically. Homeowners should still choose competent contractors.

Person Days Example

3 workers for 20 days = 60 person days (no notification needed). 5 workers for 120 days = 600 person days (notification required).

Last updated: April 2026. This is general guidance under CDM 2015 (Great Britain). Northern Ireland has separate CDM regulations. Always seek professional advice for notifiable projects.