When Is an F10 Required? A Plain Guide for UK Builders

An F10 is required when your construction project is notifiable under CDM 2015 — but not every job triggers it. You notify the Health and Safety Executive (HSE) using the online F10 form. The catch is that who does the notifying depends on whether the client is commercial or domestic, and small firms often get that part wrong. This guide breaks down when an F10 is needed, who is responsible for sending it, and how to actually get it done.

What is an F10?

The F10 is the form used to notify HSE of a notifiable construction project. You can complete it as an online form on the HSE website, and once you submit it, HSE sends you a unique serial number. That number lets you go back in and access or edit the notification later — useful if a project scope changes or you spotted a mistake.

When you complete the form, you need the contact details for three people:

• The client

• The principal designer

• The principal contractor

On a small job those roles might overlap. If you're the main builder running the works and the client has appointed you to coordinate design, you could end up filling several of those boxes yourself. That's normal on domestic and light commercial work.

Once you've made the declaration and completed the required fields, you can save the form and download a PDF copy using the 'PDF' button on the confirmation screen. Keep that PDF — it's your proof the notification went in, and you can retrieve it again later if you need it.

When is an F10 required?

An F10 is required when a construction project is notifiable. Under CDM 2015, a project is notifiable when the construction work is expected to last longer than a set duration or involves more than a set number of workers at once. If your job crosses that threshold, someone has to notify HSE before the work starts.

Because the HSE F10 guidance focuses on how to notify rather than the exact thresholds, always check the current CDM 2015 notification criteria on HSE's own pages before deciding. The point to take away is simple: short, small jobs usually aren't notifiable, but longer or larger jobs are.

Here's how that plays out on typical small-firm work:

• A two-day bathroom refit with two fitters — almost certainly not notifiable.

• A kitchen extension running several months with trades in and out — likely to be notifiable, so an F10 will be needed.

• A full house renovation lasting many weeks — check the duration and worker-count criteria carefully; this is the kind of job that often tips over into notifiable.

If you're unsure, the honest answer is to check the threshold against your programme rather than guess. Getting it wrong at the notifiable end is worse than notifying a borderline job.

Who has to send the F10?

This is where small firms trip up. The person responsible for notifying HSE depends on the type of client.

For a commercial client, the client must notify HSE. So if you're building for a business, a landlord's company, a shop or an office, the duty sits with them. In practice they may ask you to help or to do it on their behalf, but the legal duty is theirs.

For a domestic client, the notification must be carried out by someone in the project team rather than the homeowner. Domestic clients — ordinary householders having work done on their own home — generally don't carry the CDM client duties themselves. Those duties pass to the contractor or, where appointed, the principal contractor or principal designer.

What that means in the real world:

• Mrs Patel is having a loft conversion and rear extension. She's a domestic client. She won't be doing the F10. As the contractor running the job, that responsibility lands with you (or with the principal designer/principal contractor if those roles are formally appointed).

• A café owner wants a full fit-out of their unit. That's a commercial client, so the duty to notify sits with them — though you'll likely be the one reminding them it needs doing.

If you're a sole trader who takes on domestic extension work, get comfortable with the F10 process, because on notifiable domestic jobs it's often going to be your job to submit it.

How do you complete and submit an F10?

The form is completed online through HSE. Before you start, have your three sets of contact details ready — client, principal designer, principal contractor. Missing those will stall you, because you can only save the form once the required fields are done and you've made the declaration.

A practical order of work:

1. Confirm the project is notifiable by checking it against the current CDM 2015 duration and worker-number criteria.

2. Work out the client type — commercial or domestic — so you know who is responsible.

3. Gather contact details for the client, principal designer and principal contractor.

4. Complete the online F10, make the declaration, and submit.

5. Note down the unique serial number HSE gives you.

6. Download the PDF from the confirmation screen and file it with your project paperwork.

7. Print a copy to display in the construction site office or on the main site noticeboard.

If you make a typing error — say you fat-finger the email address — HSE can help you retrieve the notification details; there's a support email address on their F10 page for exactly that. And you can re-download the F10 PDF at any time using the serial number, so if you lose your copy it's recoverable.

What paperwork goes alongside the F10?

Notifying HSE with an F10 is one duty. On notifiable projects it usually sits alongside other CDM documents, and this is where the admin piles up for small firms. A notifiable project typically needs a construction phase plan (CPP) setting out how the work will be managed safely, plus risk assessments and method statements (RAMS) for the higher-risk activities.

The F10 itself is quick once you have the details. The bigger job is producing the supporting documents without spending your evenings at a laptop. That's where getting a head start helps:

• You can put together job-specific method statements and risk assessments with a RAMS generator built for trades, which is faster than starting from a blank Word file.

• For the plan that sits behind a notifiable job, creating a construction phase plan from a structured template keeps everything in one place and consistent with your RAMS.

If you'd rather understand the full set of documents before committing, the breakdown of what a proper RAMS should cover is worth a read, and the plans and pricing for The Site Book show what's included if you're producing this paperwork regularly.

Common mistakes small firms make with the F10

• Assuming the homeowner will notify. On domestic jobs they usually won't — and often can't. Check whether the duty has landed on you.

• Leaving it until work starts. Notification should be in before the notifiable work begins, not scrambled together mid-job.

• Losing the serial number. Save it and the PDF the moment you submit. You'll need the number to edit the notification if the project changes.

• Treating the F10 as the whole job. It's a notification, not a safety plan. The CPP and RAMS still have to be produced for the project to be run properly.

• Guessing whether a job is notifiable. Check your programme length and worker numbers against the current CDM 2015 criteria rather than eyeballing it.

Get the F10 right early, keep the paperwork tidy, and the rest of the project runs a lot smoother. This article is general guidance, not legal advice — always check the current HSE F10 and CDM 2015 pages for your specific job.