Construction compliance guide
A plain-English guide to F10 notifications for UK builders. When your project is notifiable, what goes in the form, and how to stay on the right side of the HSE.
The F10 is the notification form required under Regulation 6 of the Construction (Design and Management) Regulations 2015 — commonly known as CDM 2015. When a construction project is “notifiable,” this form must be submitted to the Health and Safety Executive (HSE) before work begins on site.
The purpose is straightforward: it tells the HSE who is involved in the project, what the work is, where it is happening, and when it starts and finishes. Think of it as the HSE’s register of significant construction projects across Great Britain. It means the regulator knows the work is happening and can plan inspections or respond to incidents with the right context.
The F10 is not a safety plan — it does not replace your Construction Phase Plan or your risk assessments. It is purely a notification. But it is a legal requirement, and failing to submit one when you should is a breach of CDM 2015.
Not every construction project needs an F10. A project is notifiable to the HSE if it meets either of two thresholds:
A “person-day” is simply the number of workers multiplied by the number of days they work. If you have 10 workers on site for 50 days, that is 500 person-days. If you have 5 workers for 100 days, that is also 500 person-days.
Example 1: A 6-week rear extension with 3 workers on site. That is 30 working days × 3 workers = 90 person-days. It does not exceed 500 person-days, and you never have more than 20 workers on site. This project is not notifiable.
Example 2: A new-build house with 25 workers over 8 weeks (40 working days). That is 25 × 40 = 1,000 person-days. It exceeds 500 person-days, and you have more than 20 workers on site for more than 30 days. This project is notifiable on both counts.
The F10 form asks for the key facts about your project. There are no trick questions — if you know the job, you know the answers:
The full address of the construction site where the work will take place.
The name and contact details of the person or organisation commissioning the work. On a domestic project, this is the homeowner.
The name, address, and contact details of the principal designer appointed under CDM 2015. If there is only one contractor and no principal designer has been appointed, this can be left blank.
The name, address, and contact details of the principal contractor. If you are the only contractor, you fill in your own details here.
When construction work is expected to begin on site, and how long the project is planned to last.
The maximum number of people you expect to be working on site at any one time during the project.
A short summary of the construction work being carried out — for example, “new-build 4-bedroom detached house” or “commercial office refurbishment across 3 floors.”
The F10 can be submitted online via the HSE’s official notification portal. It takes about 10 minutes if you have the information to hand.
Failing to submit an F10 when your project is notifiable is a breach of CDM 2015 Regulation 6. The HSE takes this seriously, and the consequences can be significant:
Beyond the formal enforcement, there is a practical issue: if there is an incident on site and you have not submitted an F10 when you should have, the HSE will want to know why. A missing notification suggests the project was not being properly managed under CDM 2015, which raises questions about everything else — your Construction Phase Plan, your risk assessments, your site management. It puts you on the back foot from the start of any investigation.
Working out whether your project crosses a notification threshold is not difficult — but it is easy to overlook, especially when you are busy pricing jobs and ordering materials. That is where The Site Book helps.
When you create a project in The Site Book and enter the expected duration, number of workers, and trades involved, the system automatically calculates whether your project crosses either notification threshold. It checks the 30-day / 20-worker rule and the 500 person-day rule simultaneously.
If your project is notifiable, you get a clear alert with guidance on what to do next — including a reminder to submit your F10 to the HSE before work starts. If it is not notifiable, the system confirms that too, so you can focus on the job without second-guessing the regulations.
It is one less thing to worry about. The maths happens in the background, and you get a straight answer: notifiable, or not notifiable. No spreadsheets, no manual calculations, no guesswork.
Common questions builders ask about F10 notifications.
Under CDM 2015, the client is responsible for notifying the HSE. On commercial projects, this duty sits with the client (or someone acting on their behalf). On domestic projects, the client’s duties — including notification — transfer automatically to the contractor or principal contractor. In practice, it is often the principal contractor or principal designer who submits the F10 on the client’s behalf, but the legal duty remains with the client.
The F10 must be submitted to the HSE as soon as practicable before the construction phase begins. There is no fixed number of days in advance, but the expectation is that you do it during the planning stage — not on the first day of work. If you leave it until after work has started, you are already in breach of CDM 2015. Best practice is to submit it as soon as you know the project is notifiable and you have the required information.
Yes. If project details change after you have submitted the F10 — for example the start date moves, the principal contractor changes, or the duration extends — you should submit an updated F10 to the HSE. You can do this online through the same HSE notification portal. There is no penalty for updating; the HSE expects notifications to be kept current as projects evolve.
If changes during the build mean a previously non-notifiable project becomes notifiable — for example, the programme extends beyond 30 working days with more than 20 workers, or the total person-days exceed 500 — you must submit an F10 at that point. Do not wait until the end of the project. Similarly, if key personnel change (new principal contractor or principal designer), an updated F10 should be submitted promptly.
It depends on the size of the project, not the type of client. A domestic project — such as a large extension or new-build home — is notifiable if it meets the same thresholds as any other project: more than 30 working days with more than 20 workers at any one time, or more than 500 person-days of construction work. Most small domestic jobs (kitchen refits, bathroom renovations, loft conversions) will not hit these thresholds, but a major domestic build absolutely can. If it does, an F10 must be submitted.
Filing an F10? The Site Book creates the CPP and RAMS that go alongside your notification.
If your project is notifiable, you definitely need a CPP. Even if it is not notifiable, CDM 2015 still requires one. Describe your project and get a compliant plan in minutes.
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