Jan212026

At Wilson Architectural Building Designs, we are frequently asked:

  • Do I legally need a Principal Designer?

  • What does a Principal Designer actually do?

  • Is it relevant to small residential projects?

 

When planning construction work, whether a home extension, loft conversion, or a structural alteration such as wall or chimney removal, one of the most misunderstood requirements is the Principal Designer role.

This article provides a clear, practical explanation of what a Principal Designer is, how the role works under CDM Health & Safety regulations, and why appointing the right professional can significantly reduce risk, delays, and compliance issues on your project.

What Is a Principal Designer?

A Principal Designer (PD) is a legally defined role under the Construction (Design and Management) Regulations 2015 (CDM 2015).

The Principal Designer is responsible for:

  • Planning, managing, and monitoring health and safety during the design stage

  • Identifying and eliminating foreseeable risks

  • Coordinating all designers involved in the project

  • Ensuring compliance with CDM Health & Safety obligations

If a project involves more than one contractor which applies to the vast majority of building works, you are legally required to appoint a Principal Designer.

Is a Principal Designer Required for Residential Projects?

Yes. This is a common misconception.

The CDM Regulations apply to all construction work, including domestic projects such as:

  • Home extensions

  • Loft conversions

  • Structural wall removal

  • Chimney stack removal

  • Foundations and superstructures

While homeowners do not carry the legal duties themselves, those responsibilities are automatically transferred to the Principal Designer and Principal Contractor. This makes choosing a competent, experienced Principal Designer essential.

Do You Need a Principal Designer for Your Project?

If your project involves:

  • More than one contractor

  • Structural works

  • Design input from multiple parties

Then yes, you need a Principal Designer.

Whether you are planning a home extension, loft conversion, structural alteration, or a commercial development, early appointment ensures compliance, safety, and efficiency from the outset.

Speak to a Qualified Principal Designer:

If you are unsure whether your project requires a Principal Designer—or want to appoint one with genuine structural expertise Wilson Architectural Engineering can advise and support you from concept through construction.

Contact us today to discuss your project and ensure your design is compliant, coordinated, and safe from day one!