5th September, 2023

How To Calculate If Your Construction Project Is CDM Notifiable

The CDM regulations require some construction projects to be notified to the HSE. This notification is a legal requirement and you need to let them know about your project before work starts on site. In this blog post, we look at when your project is notifiable, and how to calculate if you meet the threshold.

How To Calculate If Your Construction Project Is CDM Notifiable header image

Under the Construction (Design & Management) Regulations 2015 (CDM), certain construction projects need to be notified to the HSE, to let them know what projects are happening, where and when.

CDM notification is a legal requirement and needs to be done before work starts on the site.

In this blog post, we are going to look at when your project is notifiable, and how to calculate if you meet the threshold.

When is a construction project notifiable?

Let's start by looking at what the regulations say...

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

Ok, we can see here that there are two thresholds for notification.

So if your project lasts over 30 days with more than 20 workers at any time, or, has over 500 person days, then your construction project needs to be notified.

hard hats at site office

Just want to know if your project is notifiable? Use our free CDM 2015 notification calculator.

It sounds simple enough, and it is, but only once you understand what counts and a working day, and a person day - because these are two different things.

In 2015 the rules regarding notification requirements changed, from the previous 2007 CDM requirements. The changes were subtle but they do affect a large number of projects, so it is important to be aware of the notification terms so you don't get caught out.

Before we get into calculating working days and person days, let's make sure we know exactly what needs to be notified, and how to calculate the notification thresholds.

Notification of Domestic Projects

Domestic projects, or to be precise, projects with domestic clients (having work done on their own homes - not related to any business) were always exempt from notification under CDM 2007.

This has led some people to think that residential projects don't need to be notified to the HSE, but under 2015, domestic projects need to be notified just like any other type of project.

If you meet the notification threshold, the HSE want to hear from you, regardless of the type of project.

The 30-Day notification threshold

The first notification threshold to check is the 30-day threshold.

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

Your construction project is notifiable if it will take longer than 30 working days, and at any point, will have more than 20 workers on the site.

A working day is any day where work is taking place. If you work Saturday morning just for a couple of hours, that's a working day.

And if your project lasts for more than 30 working days, you should check how many workers you expect to have on the project at any time.

calendar

If your project usually has 5 workers, but one day you will have scaffolders, decorators and plasterers pushing you to 21, you will meet the threshold.

You could trigger the requirement on day one or day 27, but you need to notify the HSE before work starts, so plan ahead and get your notification in if you are likely to exceed the threshold.

500 person days notification threshold

If you only plan on having 10 people on site, the 30-day rule won't ever apply to your project, but does that make it un-notifiable?

No!

Now you need to calculate your person days.

If that 10-person-a-day project lasts longer than 50 days, the 500 person day rule will trigger the notification requirement.

Just want to know if your project is notifiable? Use our free CDM 2015 notification calculator.

Calculating if your project is CDM notifiable

Ok, now we know that any construction project can be notifiable, how do we calculate if your project needs to be notified? Well, you can cheat and use our free CDM notification calculator, or you can keep reading.

The first part is pretty easy to get your head around, 30 working days with more than 20 workers at any point. There's not much to calculate here. If your project will have more than 20 workers on any day, check if the project will take more than 30 working days.

scaffolders

It is important to remember that working days include "any day on which construction work takes place", so this would include weekends if work is carried out on a Saturday or Sunday. And, even if work is only carried out for part of the day, this should be considered a full working day in your calculation.

“working day” means any day on which construction work takes place;

The Construction (Design and Management) Regulations 2015 Interpretation

But what about the second part? Exceeds 500 person days - how do we calculate that? If you will always have less than 20 workers on your site, this is the notification threshold you should be considering.

To calculate if your project exceeds 500 person days you need to consider how many people you will have on your site, and then multiply that by the number of days they will be on site.

10 people working for 60 days? 10 x 60 = 600 person days. This project is is notifiable.

5 people working for 102 days? 5 x 102 = 510 person days. This project is notifiable.

2 people working for 20 days? 2 x 20 = 40 person days. This project is not notifiable.

Remember that any day work takes place is classed as a working day (or a person day in this case). If you work Monday morning and Tuesday afternoon, that might be less than 8 hours of work total, but it is still 2 working days.

For the purposes of your CDM notification calculation, any day where work takes place, even just for a short time, is a working day.

Be aware, however, that unlike CDM 2007, under CDM 2015, the notification status of your project no longer triggers additional duties.

Notifiable projects used to trigger additional duties, or, to be more accurate - there were fewer duties under CDM on non-notifiable projects. But this changed under CDM 2015.

All projects with more than one contractor (including subcontractors) now require the appointment of duty holders and documentation, such as construction phase plans, to be produced.

If your project is non-notifiable, you still must comply with all the other duties under CDM 2015, the only difference being you don't have to complete the F10 notification form.


Need help with CDM? You can use the free CDM duty holder guides to get up to speed with all the requirements.

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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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