Who is the principal designer under the Building Regulations?

When the role is needed

Where there is more than one contractor, or it is reasonably foreseeable that more than one contractor will be working on a project, the client must appoint in writing: (a) a designer with control over the design work as the principal designer for the purposes of these Regulations, and (b) a contractor with control over the building work as the principal contractor for the purposes of these Regulations.

A "contractor" is anyone who, in the course of a business, carries out, manages or controls building work (regulation 2), so a builder's subcontracted electrician or roofer counts. The appointments must be made before the construction phase begins (11D(3)(b)).

Where there really is only one contractor, that contractor is treated as the principal contractor (11D(6)). If there is then only one designer, that designer carries the principal designer duties; if there are several, they must agree in writing which of them is the lead designer and give the client a copy (11D(7)). Part 2A does not bind a client whose project consists only of the minor work listed in Schedule 4 (regulation 11P).

If you are a homeowner

A domestic client is one for whom the project is not in the course or furtherance of a business (regulation 2). Part 2A moves most of the client's management duties off you.

(1) Where the client is a domestic client the duties in regulations 11A(1) to (3) and 11E(2) to (5) must be carried out by: (a) where there is only one contractor for a project, the contractor; (b) where there is more than one contractor for a project: (i) the principal contractor; or (ii) the principal designer where the client and the principal designer agree in writing the principal designer is to fulfil those duties.

(2) If a domestic client fails to make the appointments required by regulation 11D (principal designer and principal contractor): (a) the designer in control of the design phase of the project is the principal designer; (b) the contractor in control of the construction phase of the project is the principal contractor.

Regulation 11C(3) then disapplies 11D(5), so a homeowner who appoints nobody does not become the principal designer. Besides making the appointments, what stays with you includes providing the building information you have or can reasonably get to the designers and contractors (11A(4)) and cooperating with them (11A(5)).

The gov.uk summary for domestic clients, published by the Building Safety Regulator, says you must "allocate enough time and resource" and that you "can" appoint a principal designer. The regulations read differently: the time and resources duty sits in 11A(1), which 11C(1) passes to the contractor, the principal contractor or, by written agreement, the principal designer; and 11D(1) says the client "must" appoint, with 11C(2) filling the gap if you do not.

If you are a landlord or developer

A developer, or anyone having work done in the course or furtherance of a business, including a landlord whose letting is a business, is not a domestic client. If such a client fails to appoint, it must carry out the principal designer's and principal contractor's duties itself until it does (11D(5)).

Competence

Everyone doing design work needs the skills, knowledge, experience and behaviours, or for a firm the organisational capability, to design work that complies (regulation 11F). A principal designer must also be competent for the principal designer duties (11G(1)); a firm appointed to the role must designate a competent individual to manage it (11G(2)). Someone still in training cannot be appointed (11F(5)), and a person must not act as principal designer without that competence (11E(7)(a)). For a domestic client, checking this is one of the duties 11C(1) moves off you.

The duties

The principal designer must plan, manage and monitor the design work, coordinate it so the design would comply if built, make sure designers cooperate and comply with their own duties, and liaise with the principal contractor (regulation 11M(1) to (3)). When the appointment ends it must give the client, within 28 days, a document explaining the arrangements it put in place (11M(5)(b)).

Building control sees the role three times. The full plans application names the principal designer where known (regulation 14(1)(c)). An appointment made after the application or building notice must be notified within 14 days; for a domestic client the appointee gives that notice (11O(5) and (7)). At the end, the completion notice must include a statement signed by each principal designer confirming it fulfilled its Part 2A duties, or the reasons why that statement is missing (16(4A)(e) and 16(4B)).

This is not the CDM role

CDM 2015 has its own principal designer, appointed under regulation 5 of those regulations for health and safety. The two roles share a name, a trigger and a default wording, but they are separate appointments under separate law. ClearCDM explains the CDM role and the difference in CDM principal designer vs Building Regulations principal designer. The side-by-side comparison from the Building Regulations side is in Building Regulations and CDM principal designers compared, and whether one firm can hold both is in can one person hold both roles.

What this means for you

Count the contractors, including subcontractors. If there is more than one, appoint a principal designer and a principal contractor in writing before work starts, and say in the appointment which regulations it is under. If you appoint nobody, the default in 11C(2) will decide it for you.

This guide covers England; Wales has its own dutyholder provisions. Parallel Architecture coordinates Building Regulations information as part of its design work. Get in touch to talk a project through.