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Our comprehensive guide to fulfilling your client roles and responsibilities throughout your mezzanine or fit out project.

Whether working with you on mezzanine floor installations, or a warehouse or office fit out, it’s important that you understand the relevant CDM client duties that apply to you from the outset. 

CDM client duties are laid out by the Construction (Design & Management) Regulations 2015 (CDM 2015). These are the main set of regulations for managing the health and safety procedures during any construction project.

Our handy guide will talk you through your client duties and responsibilities in-line with the CDM regulations. Don’t worry if this feels a little daunting though – we’re always on hand to help and while it’s essential you’re aware of your duties, our team are here to make sure everything is covered and nothing left to chance. Additionally, with our extensive experience as both principal contractor and principal designer, we can take all the hassle away for you – giving you the most comprehensive level of support possible. 

Before we start any fit out project or mezzanine floor installation, we’ll always ensure that you’re fully briefed and aware of your roles and responsibilities, but this page is designed to help you get a head-start on your understanding. 


The CDM regulations place responsibility for managing the health and safety of your mezzanine floor project on three main duty holders.

You, as the client, have overall responsibility for the successful management of the project, along with the Principal Designer and the Principal Contractor who are on hand to support you during the different phases of the project.

A great working relationship between the three duty holders is imperative to the success of any project and it’s essential that it’s in place from the outset. Here’s how everyone involved works together throughout the process…

Sales Meeting


One of your key CDM client duties is to ensure that your chosen Principal Designer and Principal Contractor have been vetted correctly and are implementing everything according to the CDM regulations throughout the project.

You’re also responsible for ensuring that health and safety risks present to anybody involved with the project are controlled through an effective project set-up and roll-out of those agreed practices.

Office Mezzanine Design Drawing


It’s the principal designer’s duty to ensure that all health and safety and building regulations are adhered to within their design of your new workspace or mezzanine floor installation.

They must take steps to eliminate any foreseeable health and safety risks for both you (the client), and your employees when you move into the space and also for the workers on site during the mezzanine build or fit out process.

They must also liaise with the Principal Contractor throughout the project.

Principal Contractor


It’s the principal contractor’s duty to manage the construction phase of the project, including creating a construction phase plan which details everything involved with the installation or fit out.

This must include:

  • The various build stages
  • How the three duty holders will communicate during the project
  • The identification of any dangers on site and how they will be controlled

They must liaise with the client and the Principal Designer during the entire project to ensure a smooth process.


Creating a client brief at the earliest opportunity not only helps you to ensure you’re fulfilling your CDM client duties in-line with the regulations, but it also gives you a platform to inform your chosen Principal Designer and Principal Contractor of exactly what you require from your mezzanine floor installation or fit out project.

Here are some of the key items your brief should cover:

  • Description of new facilities – include a detailed description of your requirements for your mezzanine floor or fit out project. You should also include any and all health and safety expectations of your new space.
  • Why you need the new space – explain your reasons for requiring the works, for example due to company growth, business relocation or any other reason.
  • Your expectations throughout – you should detail your expectations for health and safety procedures throughout the process. Pay particular attention to any known hazards present within your premises that could jeopardise health and safety and detail these as a starting point.
  • The design – this is the fun part! Include as much information as possible detailing the desired design of your new space. Think about the purpose of your mezzanine floor installation and the best layout for your requirements. If you’re fitting out a new office space, how many meeting rooms do you need? What kind of partitioning do you want? Is there any particular furniture or carpet style you like? The more information the Principal Designer has, the better.
  • Key contact – you’ll need to identify the key contact for any project discussions, so that both the Principal Designer and Principal Contractor know who to get in touch with regarding project updates.
  • Timeframe and budget – setting a realistic timeframe for when you would like the project to be completed and a rough budget will really help your chosen Principal Designer and Principal Contractor to plan and manage your project in accordance with your requirements.
Office Mezzanine Floor Installation
Mezzanine Floor Installation


Before the work starts, you as the client must use the pre-construction phase to make sure the upcoming work has been planned for correctly and that you’re using the correct resources and management to ensure the health, safety and welfare of all involved within the project.

The first vital step is to assign all the key works to the right people, and ensure that they’re all aware of their roles, responsibilities and any timescales involved. All arrangements you put in place should be suitable to the type of work being carried out. Each individual should also assist all other duty holders to complete their tasks safely and without creating risk to themselves and others involved within the project.

These arrangements and planning should include:

  • Your requirements for the project that have taken into consideration all risks to the public.
  • Your process for researching and appointing the appropriately skilled designers and contractors to ensure the success of your project.
  • Time and resource allocations for each stage of the project, from conception through to completion.
  • The design team’s responsibilities in regards to making considerations for any health and safety risks during the construction phase and also during the ongoing use and maintenance of the building after the project is complete.
  • The design and construction team’s procurement process, including their measures to ensure that all their suppliers have the correct training and all the required health and safety awareness.
  • How your chosen designer’s and contractor’s performance will be monitored. Regular process meetings with both the Principal Designer and Principal Contractor are useful to ascertain whether the project is meeting both legal requirements and your expectations.
  • The format that will be used for the health and safety file or the building manual that will incorporate this.
Office Fit Out
Office Facilities


If your project will involve more than one contractor, by law you must appoint a Principal Designer and a Principal Contractor. To ensure that you aren’t in a scenario where you, as the client are held responsible for the legal duties and carrying out the role of Principal Designer/Contractor, you must ensure that you appoint these roles in writing.

To ensure that you meet your legal obligations and CDM client duties, you must ensure that your chosen Principal Designer and Principal Contractor are able to deliver your mezzanine floor or fit out project in line with all health and safety requirements.

They must demonstrate:

  • The necessary capabilities and resource to carry out your project safely.
  • The correct combination of skills, knowledge, training and experience.
  • That they understand their roles and responsibilities – this may require you to ask specific questions to test their relevant health and safety knowledge.
  • Previous construction experience, whether that’s in the form of case studies of their work or offering to take you to see completed projects first hand – and allowing you to ask questions of those who previously worked with them.

Remember that the practical management of any health and safety risks is your primary objective when it comes to your CDM client duties. So make sure your enquiries relate to the provision of information that directly relate to these risks, and their ability to accommodate for and manage them.

Warehouse Mezzanine Floor
Storage Mezzanine Floor



You should gather and pass on all pre-construction information you have to your designers and contractors at the earliest opportunity. It’s best to arrange for a site survey to be conducted by your chosen Principal Designer, to ensure that all the information is accurate.

Not only will this information help with the planning of the project, but it will also advise all duty holders of any risks that need to be countered in the design, construction and future use of the facilities.

If you’re using more than one contractor, your Principal Designer is actually obligated to help put this information together with you. You’ll also need to agree with your Principal Designer what information will go into the health and safety file, which ensures other parties can use the facilities safely.

If you have other contractors or in-house contractors that offer facilities management or similar support on a fixed-term contract basis, the Principal Designer and Principal Contractor must involve these parties in the design, planning and management of the construction work.


Depending on if certain thresholds are met, you may need to notify the HSE (Health & Safety Executive) with details of the project that is to take place. For any project that is due to take longer than 30 working days – or that will require over 20 workers at one time and will exceed 500 ‘worker days’ – you will need to notify them.

The best way to do this is to fill out the online form on their website (F10 Notification of a construction project form). This way, the form is automatically sent to the HSE on completion, making it the most convenient and simple way to notify them.


As the client, it’s your duty and obligation to ensure that all pre-construction phase health and safety management arrangements are being implemented correctly, and that the Principal Designer is carrying out their agreed duties.

A great way to ensure that your mezzanine floor installation or fit out project is progressing to your agreed expectations and meeting legal requirements, is to arrange regular project meetings. These should continue into the construction phase right through to the completion of your project.

Open Plan Office Mezzanine
Office Design



Before any construction work begins, one of the most important tasks your Principal Contractor must complete is the creation of a construction phase plan. This must be written down and you should ask them to talk you through it in order to understand how the plan is project specific.

The plan should accommodate all the pre-construction information you and your Principal Designer provided regarding the site-specific health and safety risks. For further information on the construction phase plan and what should be included, check out the industry guideline for Principal Contractors.


As part of your CDM client duties, you’re required to ensure that suitable welfare facilities (such as toilets and water) are in place and ready for when the work starts. If you have existing welfare facilities on site, you can agree that workers can use them while the project is ongoing.

Alternatively, you can confirm with the sole/Principal Contractor that they’re providing these facilities in the form of portable toilets. 


During the project you must meet your responsibility to make sure that the arrangements for managing health and safety that have been put in place are working effectively, and that the Principal Contractor is complying with their duties.

We suggest two ways to help ensure this. 

  1. Conduct regular face-to-face progress meetings to discuss the project as a whole. 
  2. To further prove that you’re carrying out your CDM duties, ask the Principal Contractor to provide you with written updates.


As the end of the project is approaching, you need to discuss the plans for the handover of the mezzanine facilities or new warehouse/office fit out to you with your Principal Contractor. Depending on the nature of your project, it could be a good idea to conduct a phased handover.

This is where you gain access to areas of the facilities once the work on them is complete. This allows you to check that the health and safety measures are in place in those areas as the project progresses.

Office Reception Area
Office Mezzanine Breakout Area



It’s essential that you receive the completed health and safety file from the Principal Designer on completion of the project (or from the Principal Contractor if the designer’s involvement ended before the end of the project).

The structure, content and format of this crucial file should have been agreed between yourself and the Principal Designer at the outset of the project. The file must include all information required to ensure the health and safety of anyone involved in any future works on the building/structure. Those works include any further construction work, demolition works, cleaning and maintenance.

Before you take possession of the file, make sure that all the information contained has been reviewed and updated correctly. We advise that you conduct a meeting with the appropriate duty holder that has passed it to you to discuss the contents and become aware of any key risks.


Once the project is complete and the health and safety file has been handed over to you, you must ensure that the file is stored in a durable format such as an electronic/digital file, physical/paper file or on a film.

To reduce any risk of losing timely access to this essential information, we recommend that you store the health and safety file separately from the building maintenance manual. In the event that responsibility of the premises is handed on to a new owner (or possibly shared), the health and safety file must be provided to every new owner or leaseholder.

You must provide clear instructions to them as to the nature of the file. You also have a responsibility to regularly revisit, revise and update the file when required, and must also ensure that any party that needs it to ensure they comply with health and safety law are able to access it.

Large Office Fit Out
Office Meeting Room



We can make your mezzanine floor installation or office/warehouse fit out project hassle-free, by using our vast experience in acting as both principal designer and contractor on numerous projects. At Nexus Workspace, we make complying with HSE law nice and simple, while also delivering the best possible solution for your individual needs.


We make everything easier for you. We provide a complete mezzanine floor solution from site survey through to the completion and handover of your new facilities. Our expert team of designers, project managers and construction team will guide you through every step of your mezzanine floor installation or fit out project.


We have the strictest building regulations and health and safety practices in mind when we design and implement your new warehouse mezzanine, office mezzanine or fit out project. The safety of all involved is at the forefront of everything we do throughout the process, and you can be assured that all the correct procedures will be carried out during your project.


We’d love to be able to carry out fit our projects and mezzanine floor installations to businesses throughout the whole of the UK, but unfortunately this isn’t possible. The extra cost to you and the fact that we wouldn’t be able to manage your project to our usual high standards means that we must set a limit for how far we can work.
As you can see from our coverage area indicated here, we essentially work as far North as Newcastle and as far South as Birmingham. So if your business is situated within our service area, get in touch to discuss your plans for your new workspace.

Nexus Where We Work


If you’re looking for a stress-free mezzanine floor installation service or an entire office or warehouse fit out – with support to manage your CDM client duties throughout – please get in touch with our friendly, knowledgeable team who’ll be happy to answer your questions.