8th May, 2024

CDM Notifiable Projects Working Days And Person Days Explained

Notifiable CDM projects are construction projects that you need to tell the HSE about. If your construction project meets certain criteria - based on project length and the number of people on site - you have to notify the HSE, and your project is notifiable.

CDM Notifiable Projects Working Days And Person Days Explained header image

If a construction project meets the notification criteria, the HSE want to know about it. But do you know if your construction project needs to be notified to the HSE?

To find the answer to this question, you need to know about:

Because if your project is over 30 working days with more than 20 workers, or if it's over 500 person days, then it's a notifiable project under CDM.

What are CDM notifiable projects?

Some construction projects in the UK have to be notified to the HSE. These are projects that meet certain thresholds, in terms of how long the project will take, and how many people are working on it.

The Construction (Design and Management) Regulations (CDM) apply to every construction project in Great Britain. So, hopefully, if you work in construction, you have at least heard of these regulations. If you're not too familiar, we have some free CDM guides to get you up to speed.

However, while CDM applies to every construction project, not every construction project is CDM notifiable.

Just need to know if your project is notifiable? Use our free CDM notification calculator to find out!

Simply put, notifiable projects are construction projects that need to be notified to the HSE. And only some do.

Any type of construction project can be notifiable. If your construction project meets certain criteria (based on project length and the number of people on your site) then you have to notify the HSE, and your project is notifiable.

cdm project meeting

Under previous versions of the CDM regulations, having a notifiable project meant extra requirements. But, under the current 2015 version, the notification doesn't make a big difference. The rest of CDM applies, even if your project is not notifiable.

For example, all construction projects need a construction phase plan. And all projects with more than one contractor need a principal designer and principal contractor.

If your project is notifiable, it means just that. Your project needs to be notified to the HSE. It's just an extra requirement on top of the other duties you need to comply with, regardless of project size and duration.

Still, if you fail to notify, you could be in a bit of trouble. It's in the regulations, so it's a legal requirement.

How do you know if your project needs to be notified? Well, there are two criteria, known as notification thresholds.

If you meet either of these criteria, then your project must be notified.

6.—(1) A project is notifiable if the construction work on a construction site is scheduled to—

  1. last longer than 30 working days and have more than 20 workers working simultaneously at any point in the project; or
  2. exceed 500 person days.
The Construction (Design and Management) Regulations 2015 Notification

If your construction project exceeds either one of these thresholds, then it is notifiable under the CDM regulations.

And if you're wondering what a person day is or what counts as a working day, don't worry, we're going to break that down for you! Let's take a more detailed look at the two notification thresholds.

30 working days

What's a working day? Monday to Friday? What if you only work weekends? What about evenings, do they count?

Under the CDM regulations, a working day is classed as any day on which construction work takes place. That means any day a worker clocks in to dig a hole, put up a shelf, or knock down a wall. Even if the planned construction work on one day will only take 2 hours, it will need to be classed as a working day when determining if the project is notifiable.

Just working a Tuesday evening? That's 1 working day.

Just doing an hour on a Saturday? That's 1 working day.

electrician at work

You will need to count weekends if any construction work is likely to take place. For example, if you were planning to do a couple of hours on a Saturday as well as working in the week, then this will count as an extra day towards the notification threshold.

You can't combine half days either. For example, if you do 8 hours work on a Monday. That's one working day. If you do the same 8 hours work, but carry out 4 hours on a Tuesday, and 4 hours on a Wednesday, that's two working days.

For example, a project lasting 6 weeks with construction work occurring Monday – Friday (5 x 6 = 30) will come in just under the 30-day threshold. However, the same project with Friday's work spread across Friday morning and Saturday morning (6 x 6 = 36) will be over 30 working days.

Now, don't forget, under CDM 2015, your project is only notifiable for the 30 working day threshold if you also have more than 20 workers on-site at any point. A lot of smaller projects might not have this number of workers, but even if you don't reach 20 workers, you still need to consider the person-day threshold.

500 person days

The second criteria, and possibly the more common of the two under the latest version of the regulations, is 500 person days.

A person day is one person's working day. Each day a person works, they clock up one person day under CDM.

If you have a project that is 25 working days, and you have 2 people working each of those days, then you would reach 50 person days. Some projects have more than one shift per day, for example, a day shift and a night shift. So in one day, if you have 10 people on the day shift and 10 people on the night shift, you would have 20 person days.

math sums on paper

The same rules apply to person days as they do to working days. Partial days count as working days. However, to calculate these as person days, you multiply your working days by the number of people on site.

If somebody works for an hour on a Saturday, that's one person day.

If two people work for an hour on a Saturday, that's 2 person days.

While 500 sounds like a bigger number, and you might think it would only apply to bigger projects, the 500-person-day threshold can apply even to projects under the 30 working-day threshold.

A project lasting 20 days does not pass the threshold in the working day test. However, if that project was expected to have 40 people on site each day, or 20 people working days and 20 people working nights, then the project would have 800 person days of construction work and would be notifiable. (20 days x 40 workers = 800 person days).

If you have a 6-month project with 4 workers, you could also clock up over 500 person days. (130 days x 4 workers = 520 person days).


Too much math? Use our free CDM notification calculator to find out if your construction project is notifiable!

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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