What is an F10 notification, and when do you need one?

An F10 is the notification form used to tell the HSE about a construction project, submitted via HSE's online system. Under CDM 2015, a project is notifiable if it's expected to last longer than 30 working days and have more than 20 workers on site at any one time, or exceed 500 person-days of construction work — thresholds worth checking directly against current HSE guidance, since exact figures are exactly the kind of detail that shouldn't be relied on secondhand.

The notification is the client's responsibility, though in practice it's often handled by the principal designer or principal contractor on the client's behalf. It has to be submitted before construction work starts, and a copy displayed on site.

What actually goes on the form

An F10 asks for more than just "yes, this project exists." It covers a description of the project and the work involved, the address, the client's details, the details of the principal designer and principal contractor, the planned start date and estimated duration, and an estimate of the maximum number of people expected on site at any one time. None of this is meant to be a rough guess submitted just to tick the box — the estimated duration and workforce numbers are what determine whether HSE flags a project for closer attention, so they're worth getting genuinely right rather than padding out to look safe or shrinking to avoid scrutiny.

Displaying it on site

Once submitted, a copy of the notification has to be displayed on site in a place workers and visitors can actually see it — typically alongside the construction phase plan and other site documentation at the entrance or site office. This isn't just a formality: an HSE inspector visiting an unfamiliar site will often check for it early, since it's a quick indicator of whether the project's basic CDM administration is in order.

Keeping it current

It's also worth keeping the notification current — if key details change materially during the project, such as the principal contractor changing, the project extending well beyond its original estimated duration, or the scope of work expanding significantly, an updated notification may be needed. This is easy to overlook once a project is already underway and attention has shifted to the work itself, but an F10 that describes a project as it was six months ago, run by a contractor who's since been replaced, isn't doing its job.

What happens if you don't notify

Failing to notify a notifiable project is a breach of CDM 2015, and it's not a technicality HSE tends to overlook — notification is one of the most straightforward things to check, so a project that should have been notified and wasn't is an easy finding for an inspector to make. If a project turns out to be notifiable partway through — because it's overrun its original timeline, or the workforce numbers on site have grown past the threshold — it should be notified at that point rather than left unreported on the basis that the original plan didn't require it.

Multi-site and phased projects

Projects delivered in phases, or across what's nominally one contract but genuinely separate sites, raise a judgement call about whether each phase or site needs its own notification or whether one notification covers the whole programme. This is genuinely fact-specific — it depends on how the work is structured and managed — and is worth checking directly with current HSE guidance or a CDM adviser rather than assuming the answer either way, since getting it wrong in either direction (over-notifying or under-notifying) creates avoidable admin or avoidable risk.

Why subcontractors should know a project is notified

It's easy to treat the F10 as purely an administrative exchange between the client and HSE, with subcontractors and their workforce having no real reason to know or care that it exists. In practice, it's worth making sure it's visible and understood on site, not just displayed as a piece of paperwork nobody reads. A notified project generally signals a certain scale and duration of work, which has knock-on implications for how welfare facilities, site coordination and inspection frequency are expected to scale — a subcontractor turning up for a two-day job on a project they don't realise is notified and long-running may not appreciate that the level of coordination and documentation expected of them is correspondingly higher than on a small, one-off job.

Mixed portfolios — notifiable and non-notifiable side by side

A business running several concurrent projects will often have some that are notifiable and some that aren't, and it's worth being careful not to let the administrative habits from one bleed sloppily into the other. A non-notifiable project still needs a construction phase plan if it involves more than one contractor — the F10 threshold and the requirement for a principal contractor and construction phase plan aren't the same test, and it's a genuine mistake to assume a smaller project is exempt from CDM coordination requirements just because it doesn't need notifying to HSE.

A simple habit that avoids most of the problems above

Most of the practical issues with F10 notification — missing the threshold when a project overruns, forgetting to update details after a change of principal contractor, not displaying it on site — come down to the notification being treated as a one-off task rather than something revisited at fixed points through the project. Building a short check into existing project review points, rather than relying on someone remembering to think about it independently, tends to catch these issues well before they become a genuine compliance gap.