Client, designer and contractor duty holder responsibilities

Overview 

Below is simple summary of The Building Regulations 2010 Part 2A

Updates to the Building Regulations have changed the application process and clarified who is responsible for compliance. The client, principal designer, and principal contractor now hold overall responsibility for making sure building work meets the regulations.

Changes introduced by the Building Safety Regulator and new licensing rules for Building Inspectors have also changed how building control works. Building control is no longer part of the design team—its role is strictly to inspect and enforce the regulations.

Building control bodies will not give design advice or solutions. Designers and contractors must ensure their work complies with the regulations, and any non‑compliance must be fixed by qualified professionals. Clients must also make sure they appoint competent teams and have the necessary funding and contracts in place.

While we will continue to work proactively under the new system, our involvement will focus only on checking regulatory compliance. Ultimately, responsibility for compliance remains with the client and the designers and contractors they choose to appoint.

Duty Holders 

These roles cover people responsible for planning, designing, managing, and carrying out building work and must be clearly identified on every project.

Client: - a person for whom the project is carried out 

The client is responsible for ensuring the project is properly planned, managed, and monitored so it complies with building regulations throughout design, construction, and the life of the building. 

They must appoint competent principal duty-holders. The client retains overall responsibility for providing accurate project information—maintaining an information trail, If designers or contractors change, information must be handed over, and the new duty-holders must notify the authority. While tasks can be delegated, the client cannot delegate their overall legal responsibility and must ensure all appointed individuals are suitably qualified.

Principal Designer: - usually the lead designer

Appointed by the client. Responsible for leading and controlling the pre‑construction (design) phase on projects.  Plan, manage and monitor all design work during the design phase.  Ensure all design work—both their own and that of anyone they supervise is managed so the final building will comply with building regulations. Ensure effective cooperation, communication and coordination between the client, principal contractor, designers and contractors. Liaise with the principal contractor and share all relevant design and safety information. Help the client gather and provide necessary information to designers. Review arrangements put in place by any previous principal designer. Notify building control in writing, where required, for domestic client projects. Sign required declarations once work is completed (where applicable).

Principal Contractor - usually the lead contractor

The principal contractor is usually the main contractor. They are appointed under Regulation 11D when a project has more than one contractor. Their job is to manage the construction phase and ensure the work complies with building regulations. Plan, manage and monitor the construction work during the build. Coordinate all building activities so that everything complies with building regulations. Ensure all duty holders cooperate with each other. Ensure contractors follow their legal duties.  Work with the principal designer as needed. Consider any compliance-related comments from the principal designer. Help the client provide necessary information to contractors. Notify building control in writing (when required) that work for a domestic client is being carried out. Sign the required declarations when the work is finished.

Completion

On completion of a project

The duty holders involved in the construction phase (client, principal designer, principal contractor) must provide compliance declarations to RBC building control confirming they have fulfilled their duties and that, to the best of their knowledge, the works comply with the building regulations. 

Completion Notice (England).pdf

A completed duty holder declaration document must be provided to building control before a completion certificate can be issued. 

Last modified: 26/03/2026