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Part of our CDM 2015 series. See CDM Regulations 2015 explained for every duty holder and key document in one place.
An F10 is the form used to notify HSE of a construction project under CDM 2015 regulation 6. Not every project needs one, but those that do must be notified before the construction phase begins, and the notice must be displayed on site.
When a project must be notified
A project is notifiable if the construction work is expected to:
- Last longer than 30 working days and have more than 20 workers working at the same time at any point in the project, or
- Exceed 500 person days
Working days and person days
| Term | What it means |
|---|---|
| Working day | Any day on which construction work takes place, including weekends and bank holidays if work happens on them. |
| Person day | One person, including supervisors and specialists, carrying out construction work for one normal working shift. |
Worked examples
| Project | Notifiable? |
|---|---|
| Office refurbishment lasting 8 weeks (40 working days) with a peak of 25 workers on site at once | Yes. More than 30 working days and more than 20 workers at the same time. |
| Extension lasting 12 weeks (60 working days) with never more than 6 workers on site | No. At most 6 workers for 60 days is 360 person days, and never more than 20 workers at once. |
| Warehouse build with 12 workers a day for 50 working days (600 person days) | Yes. It exceeds 500 person days. |
| Shop fit out lasting 10 working days with 40 workers at once | No. It lasts under 30 working days, and 40 workers for 10 days is 400 person days. |
Who must notify?
Notification is the client’s duty. Someone else, such as the principal designer or principal contractor, can submit it on the client’s behalf, but the duty stays with the client. For domestic clients, the duty passes to the contractor or principal contractor along with the client’s other duties.
When and how
Notify HSE as soon as practicable before the construction phase begins, using HSE’s online F10 form. Not all the details may be known at that point, so give what you have and update the notification as the project develops.
What the F10 asks for
- The address of the site and the local authority
- A brief description of the project and the construction work
- Contact details for the client, the principal designer and the principal contractor
- The planned start date and how long the construction phase will last
- The estimated maximum number of people at work on site at any one time
- The planned number of contractors
- Details of designers and contractors already appointed
- A declaration by or on behalf of the client that it is aware of its duties
Displaying the notice
The principal contractor, or the contractor on a single contractor project, must make sure a copy of the notification is displayed in the site office where workers can read it, and keep it up to date.
What notification does not do
Under CDM 2007, notification triggered extra appointments. That is no longer the case. Under CDM 2015 the need for a principal designer and principal contractor depends on the number of contractors, not on notification, and every project needs a construction phase plan whether it is notifiable or not.
Training that helps
Site managers deal with the F10 and the site notice, which is why notification is covered on SMSTS. Our CDM awareness eLearning is a quick introduction, and the NEBOSH Health and Safety Management for Construction certificate covers CDM in depth.
Where this fits in SMSTS and SSSTS
Notification thresholds are a favourite exam question on both courses. Our free SMSTS mock test and SSSTS mock test let you check your knowledge before the course or a refresher, and you can email yourself the results sheet at the end.
When you are ready, the five day SMSTS course is for site managers and the two day SSSTS course is for supervisors. If your certificate is due, the SMSTS refresher and SSSTS refresher keep it current.
Frequently asked questions
What is an F10?
The form used to notify HSE of a construction project under CDM 2015 regulation 6.
When is an F10 required?
When construction work will last more than 30 working days with more than 20 workers at the same time at any point, or will exceed 500 person days.
Who submits the F10?
The client has the duty. Others can submit it on the client’s behalf, and for domestic clients the duty passes to the contractor or principal contractor.
Does a notifiable project need extra appointments?
No. Under CDM 2015 the principal designer and principal contractor are needed when there is more than one contractor, whether or not the project is notifiable.
Where must the F10 be displayed?
In the construction site office, where workers can read it.
Read the source
The Construction (Design and Management) Regulations 2015, regulations 2 and 6 and Schedule 1; HSE guidance L153, Managing health and safety in construction; and HSE’s online F10 notification service and guidance. Facts checked on 6 October 2026.
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