Under the Construction (Design and Management) Regulations 2015, certain construction projects must be notified to the Health and Safety Executive (HSE) before work begins. This notification, known as an F10, is a legal requirement for projects that meet specific thresholds.
Will your construction project exceed these thresholds?
Select what applies to your project
When is notification required?
A construction project must be notified to the HSE if the construction work is expected to:
- Last more than 30 working days AND have more than 20 workers working simultaneously at any point in the project, OR
- Exceed 500 person days of construction work
Person days are calculated by multiplying the number of people on site by the number of days they work. For example: 10 workers working for 50 days = 500 person days. This meets the notification threshold.
Understanding the thresholds
Threshold 1: 30+ days AND 20+ workers
Both conditions must be met:
- The construction phase lasts longer than 30 working days (not calendar days)
- At some point during the project, there will be more than 20 workers on site at the same time
Example: A 6-week office refurbishment with 25 workers on site during the fit-out phase is notifiable.
Threshold 2: 500+ person days
This is calculated by adding up all person days across the entire project.
Examples:
- 10 workers × 50 days = 500 person days (notifiable)
- 5 workers × 100 days = 500 person days (notifiable)
- 20 workers × 30 days = 600 person days (notifiable)
- 8 workers × 40 days = 320 person days (not notifiable)
When calculating whether your project is notifiable, base your estimate on what you reasonably expect at the planning stage. If circumstances change and the project becomes notifiable, you must notify the HSE as soon as you become aware.
What counts as a working day?
A working day is any day on which construction work takes place.
Include:
- All days when construction work is being carried out
- Days when only a few workers are on site
Don't include:
- Weekends when no work takes place
- Public holidays when the site is closed
- Days when design work is happening but no construction
- Days when the site is shut down due to weather, holidays, or other reasons
What counts as a person day?
Person days means the total number of people carrying out construction work multiplied by the number of days they spend on site.
Include:
- All contractors, subcontractors, and their workers
- Self-employed workers
- Any person carrying out construction work
- Part days count as full days
Don't include:
- Delivery drivers who only drop off materials (unless also installing)
- Client's staff visiting the site
- Inspectors or consultants not carrying out construction work
- People working off-site (e.g., designers in their office)
Notifiable vs Non-Notifiable Projects
Notifiable Project
- •Exceeds 30 days + 20 workers OR 500 person days
- •F10 notification required before work starts
- •Must appoint Principal Designer
- •Must appoint Principal Contractor
- •F10 notice must be displayed on site
- •Construction Phase Plan required
- •Health and Safety File required
Non-Notifiable Project
- •Below notification thresholds
- •No F10 notification required
- •No need for formal Principal Designer appointment
- •No need for formal Principal Contractor appointment
- •F10 display not required
- •Still need construction health and safety planning
- •Still need health and safety information for future work
Bottom line: Even if your project isn't notifiable, you still have CDM duties. The work must be properly planned, managed, and monitored to ensure health and safety.
What information must be included in F10 notification?
The F10 notification must include:
Project details
- Exact address of the construction site (including postcode)
- Brief description of the project and construction work
- Name of the local authority where the site is located
Project timing
- Date when construction work is planned to start
- Planned duration of the construction phase
- Estimated maximum number of people at work on the site
- Estimated number of contractors expected to work on the site
Client information
- Client's full name
- Client's full address and postcode
- Client's telephone number
Principal Designer information
- Name of the organisation or individual
- Full address and postcode
- Telephone number
Principal Contractor information
- Name of the organisation or individual
- Full address and postcode
- Telephone number
Declaration
- Signed by or on behalf of the client
- Declaration that the information is correct
The client is responsible for the accuracy of the information in the F10, even if someone else completes it on their behalf. Make sure all details are correct before submitting.
How to notify the HSE
There are two ways to submit an F10 notification:
1. Online via HSE website (recommended)
Advantages:
- Instant submission
- Immediate confirmation
- Can save and edit before submitting
- Automatic validation of required fields
- Electronic record
How to submit:
- Go to the HSE website (www.hse.gov.uk)
- Search for "F10 notification" or navigate to the construction section
- Complete the online F10 form
- Review all information carefully
- Submit electronically
- Print or save the confirmation email
The HSE online notification system is the quickest and most reliable method.
2. By post
You can download a paper F10 form from the HSE website and post it to your local HSE office.
Address: Send to the HSE office responsible for the area where the construction site is located (check HSE website for regional office addresses).
Important: Postal notification takes longer. Allow extra time to ensure the HSE receives it before your construction start date.
Most clients, Principal Designers, or Principal Contractors now use the online HSE portal. It's faster, provides immediate confirmation, and creates an automatic record of submission.
When must you notify?
Timing requirements
You must notify the HSE before the construction phase begins.
The notification should be made:
- As early as possible in the project planning
- At the latest, before construction work starts on site
Best practice is to submit the F10 notification as soon as you've appointed the Principal Designer and Principal Contractor, and you have a confirmed construction start date. Don't wait until the last minute.
Can I submit before appointments are made?
Ideally, you should have appointed both the Principal Designer and Principal Contractor before submitting the F10, as you need to include their details.
However, if timing is tight, you can submit the F10 with the information you have and notify the HSE of any changes later.
What if project details change?
If any of the following change after you've submitted the F10, you should notify the HSE:
- Change of Principal Designer
- Change of Principal Contractor
- Significant change to project scope or duration
- Change of site address
You can notify the HSE of changes by submitting an updated F10 or by writing to the HSE office that covers the area.
Minor changes like a slightly extended timeline or a different subcontractor don't require an updated notification. Use your judgement: if it significantly affects the information originally provided, update the HSE.
Who is responsible for notifying?
The client's duty
Under CDM 2015, notifying the HSE is the client's duty.
The client is legally responsible for ensuring:
- The project is correctly identified as notifiable
- The F10 is submitted before construction starts
- The information provided is accurate
- The F10 notice is displayed on site
Even if the client is a domestic client (homeowner), if the project is notifiable, it must be notified. For domestic projects, the duty typically transfers to the Principal Designer or Principal Contractor.
Can someone else submit on behalf of the client?
Yes. In practice, one of the following often submits the F10 on the client's behalf:
- Principal Designer — Often submits during the pre-construction phase
- Principal Contractor — May submit if appointed early
- Project manager or client's agent — If managing the project
However, the client remains legally responsible, even if someone else physically submits the form.
The client must:
- Ensure the notification is submitted
- Check that the information is correct
- Ensure the declaration is signed by or on behalf of the client
Display requirements on site
Once you've submitted the F10 notification, you must display a copy of it on the construction site.
Where to display
The F10 notice must be displayed:
- In a position where it can be easily seen by anyone visiting the site
- At the main entrance or access point to the site
- Protected from the weather (e.g., in a weatherproof display case or laminated)
Typical locations include:
- Site entrance gate
- Site hoarding
- Site office window
- Contractor's notice board
What to display
Display either:
- A copy of the completed F10 form, OR
- A site notice containing the key F10 information (project address, client, Principal Designer, Principal Contractor, HSE notification confirmation)
Many Principal Contractors create a site notice board that includes the F10 information alongside other site information like emergency contacts, site rules, and welfare facility locations.
How long to display
The F10 notice must remain displayed:
- Throughout the construction phase
- Until the project is completed or handed over
What happens if you don't notify?
Failure to notify the HSE when required is a criminal offence under CDM Regulations.
Enforcement action
The HSE can take the following action:
Improvement Notice
- HSE serves a notice requiring you to submit the F10 by a specified date
- You must comply with the notice
- Failure to comply is a criminal offence
Prohibition Notice
- HSE can stop all work on site until notification is made
- Work must not resume until the notice is lifted
- Continuing to work in breach of a prohibition notice is a serious offence
Prosecution
- Failing to notify is a breach of CDM Regulation 6
- Penalties include unlimited fines
- In serious cases, imprisonment for up to 2 years
- Company directors can be personally prosecuted
Developer fined £15,000 for failing to notify HSE
A property developer undertook a residential conversion project expected to last 8 weeks with 25 workers on site at peak. HSE inspectors visited the site and discovered no F10 had been submitted.
- ✗Project clearly met notification thresholds (30+ days and 20+ workers)
- ✗No F10 notification submitted before work started
- ✗No F10 notice displayed on site
- ✗No Principal Designer formally appointed
- ✗Developer claimed they didn't know notification was required
The developer was prosecuted and fined £15,000 plus £8,000 costs. HSE issued an improvement notice requiring immediate notification and formal appointments.
Ignorance of CDM requirements is not a defence. Always assess whether your project is notifiable at the planning stage and ensure the F10 is submitted before work starts. If in doubt, consult a CDM specialist.
Insurance implications
Failing to notify can also affect insurance:
- Some insurance policies require CDM compliance as a condition
- Claims may be rejected if you breach CDM requirements
- Professional indemnity insurers may refuse to cover losses arising from non-compliance
Project delays
If the HSE discovers your project wasn't notified:
- Work may be stopped immediately
- Delays while appointments are made and F10 submitted
- Contractors may demobilise, causing further delays
- Additional costs from extended programme
The consequences of failing to notify far outweigh the time and effort required to submit an F10. Always identify notifiable projects early and submit the notification before starting on site.
Projects that don't require notification
Your project does NOT need to be notified if:
Below the thresholds
- The project will last 30 days or less, OR
- It will last more than 30 days but never has more than 20 workers on site, AND
- The total person days are below 500
Examples of non-notifiable projects:
- Small office refurbishment lasting 3 weeks with 10 workers
- Kitchen and bathroom replacement in a domestic property (4 weeks, 3-5 workers)
- External decoration of a small building (2 weeks, 6 workers)
- Retail shop fit-out lasting 4 weeks with 15 workers
Exemptions
Some work is not construction work under CDM, so notification never applies:
- Tree surgery — Not construction work
- Archaeology — Not construction work
- Pure maintenance by permanent employed staff that doesn't involve structural alteration
- Cleaning work that doesn't involve specialist access equipment or work at height
Even if your project is not notifiable, you still have CDM duties. You must plan the work, manage risks, provide welfare facilities, and ensure competent people are appointed.
What if I'm not sure?
If you're uncertain whether your project is notifiable:
Step 1: Estimate the duration and numbers
Make a reasonable estimate based on:
- The scope of work
- Your contractor's programme
- Typical crew sizes for the work involved
- Any specialist activities that need more workers
Step 2: Apply the thresholds
Check if the project will:
- Last more than 30 working days AND have 20+ workers at any point, OR
- Exceed 500 person days total
Step 3: Err on the side of caution
If you're borderline or uncertain:
- Assume the project is notifiable
- Appoint Principal Designer and Principal Contractor
- Submit the F10 notification
There's no penalty for notifying when not strictly required. There are serious penalties for failing to notify when you should have.
F10 Notification Timeline
Estimate project duration and worker numbers to determine if thresholds will be met
Client appoints competent Principal Designer for pre-construction phase
Client appoints competent Principal Contractor before construction phase
Client (or on their behalf) submits F10 via HSE online portal or by post
Principal Contractor displays F10 notice at site entrance where it can be easily seen
Notify HSE of any significant changes to Principal Designer, Principal Contractor, or project scope
Notification checklist
Use this checklist to ensure you meet F10 notification requirements:
Before submitting
- Confirmed project exceeds notification thresholds (30+ days + 20+ workers OR 500+ person days)
- Appointed competent Principal Designer
- Appointed competent Principal Contractor
- Gathered all required information (project details, client details, appointee details)
- Confirmed planned construction start date
- Obtained client approval to submit (if submitting on their behalf)
Submitting the F10
- Accessed HSE online notification portal (or printed paper form)
- Completed all required fields accurately
- Double-checked addresses, postcodes, and contact details
- Included client declaration/signature
- Submitted notification
- Received and saved confirmation from HSE
On site
- Printed copy of F10 or site notice with F10 information
- Displayed F10 at main site entrance in weatherproof holder
- Ensured notice is clearly visible to anyone entering site
- Checked notice remains displayed throughout construction phase
- Will remove notice only when construction phase is complete
If changes occur
- Noted any significant changes (Principal Designer, Principal Contractor, project scope)
- Notified HSE of changes by submitting updated information
- Updated displayed F10 notice on site if necessary
Frequently asked questions
If circumstances change during the project and it becomes notifiable (e.g., the scope expands or takes longer than expected), you must notify the HSE as soon as you become aware. You'll also need to appoint a Principal Designer and Principal Contractor if you haven't already. Don't wait until the project is complete.
Ideally, both Principal Designer and Principal Contractor should be appointed before submitting the F10. However, if you need to submit urgently, you can submit with the Principal Designer details and add the Principal Contractor later by updating the HSE. The Principal Contractor must be appointed before the construction phase begins.
No. If it's one project with a continuous programme, one F10 covers the entire project. However, if there are completely separate projects at the same location (e.g., Phase 1 completed and handed over, then Phase 2 starts months later), each may need its own F10.
If your domestic project is notifiable, the duty to notify transfers to either the Principal Designer or Principal Contractor. However, you should still check that they have submitted the F10. Most domestic projects are not notifiable (they're typically shorter and involve fewer workers).
No. The HSE uses F10 information for statistics and to target inspections based on risk. High-risk projects, larger projects, or those in sectors with poor safety records are more likely to receive HSE visits. However, any notified project could be inspected at any time.
The F10 must be submitted before the construction phase begins. There's no specific minimum notice period, but best practice is to submit as early as possible once you know the project is notifiable and have appointed the Principal Designer and Principal Contractor.
If you discover mid-project that you should have notified, submit the F10 immediately. Don't wait. While this is a breach (work should not have started without notification), submitting late is better than not submitting at all. You may still face enforcement action.
Yes. Each construction site requires its own F10 notification if it's notifiable. You can't submit one notification covering multiple sites, even if they're part of the same programme or contract.
Minor variations don't require an update. If there's a significant change (e.g., project extended by several months), it's good practice to notify the HSE of the revised timeline, though it's not always legally required unless it affects the notifiable status.
Next steps
Want to understand all your CDM duties, not just notification?
What is CDM? Full guide to CDM Regulations →
Need to know what a Principal Designer actually does?
Principal Designer duties explained →
Not sure if CDM applies to your project at all?
Still unsure if your project needs notification, or need help submitting the F10? A CDM specialist can assess your project, handle the notification process, and ensure all appointments are made correctly.
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