Domestic Building Projects & the Building Regulations

A Detailed Guide for Homeowners, Builders and Consultants

The Building Safety Act 2022 (BSA) and subsequent updates to the Building Regulations 2010 have significantly altered the legal landscape for all building work in England, including domestic projects.

Whether you're a homeowner planning a modest extension, a builder undertaking refurbishment work, or a designer providing architectural or structural input, you now have clearly defined legal duties under this updated regulatory framework.

This guide offers a detailed explanation of those duties, with particular attention to how responsibilities are assigned on domestic work when no formal appointments are made. For commercial work and information relating to Higher Risk Buildings (HRBs), see our article Navigating the Building Safety Act: A Guide to Compliance with Shepherd Gilmour.

Why Domestic Projects Are Affected by Building Regulations

While the BSA is often associated with HRBs, the regulatory changes introduced to the Building Regulations 2010 (as amended) apply new dutyholder roles, competency requirements, and compliance obligations across all construction work, including minor domestic schemes.

This means: All projects — whether a loft conversion, kitchen extension or internal structural alteration — are now subject to enhanced safety, competence and documentation standards.

Who Is Responsible for What?

1. Homeowners (Domestic Clients)

Under Regulation 11C of the Building Regulations (as amended), the homeowner commissioning the works is the legal Client. Clients are responsible for ensuring that the project complies with the Building Regulations.

However, recognising that most homeowners are not construction professionals, Regulation 11C(2) states that, unless a domestic client makes a formal appointment, their duties are automatically discharged as follows:

• To the Principal Designer for design-phase duties

• To the Principal Contractor for construction-phase duties

  
  

Summary for Homeowners:

• You remain the legal Client, but others take on responsibility by default

• This default discharge applies only if no written appointments are made

• It is essential to document who is taking on what role — or confirm who has declined

  
  

2. Designers and Engineers

Any party creating or modifying drawings, specifications or calculations is a Designer.

According to Regulation 11C(2)(a), The Principal Designer (PD) is the designer in control of the design phase of the project. In other words, the party responsible for planning, managing and monitoring the design phase of the work.

For domestic projects:

• If the first appointment made is a Designer (e.g. architect or engineer), and no one is formally appointed as PD, that Designer automatically assumes PD duties

• They must formally decline in writing if they do not wish to act in this role

Principal Designers are legally required to:

• Ensure designs comply with the functional requirements of the Building Regulations

• Coordinate with other designers and the contractor

• Manage foreseeable risks related to the design

This default mechanism ensures that someone always takes responsibility for safety and compliance during the design phase, even if the homeowner does nothing to initiate it.

3. Builders and Contractors

According to Regulation 11C(2)(b), The Principal Contractor (PC) is the contractor in control of the construction phase of the project is the principal contractor.  Simply put, they are responsible for managing the construction phase and ensuring the works comply with the Building Regulations.

For domestic works:

• If no PC is formally appointed, the first Contractor engaged automatically assumes this duty, provided they are competent to do so

Principal Contractors must:

• Plan and manage the site and sequencing of works

• Coordinate with the Principal Designer

• Ensure works are carried out safely and in compliance with the Building Regulations

Important clarification:

• A Contractor cannot act as Principal Designer unless they are also undertaking design work (per the definition of “Designer” in Regulation 2)

• This means a general builder who does not prepare or modify designs cannot legally discharge PD duties

Competency Requirements for All Parties

All dutyholders must be competent — either as individuals or organisations.

Defined under Regulation 11B, this requires appropriate skills, knowledge, experience (SKE), and where relevant, organisational capability.

Local Authority Building Control or Approved Inspectors may require evidence of competence at any point. If inadequate, they may delay or refuse approval, issue enforcement notices, or escalate matters under the Building Act 1984.

Documentation and Evidence

While not all domestic projects require elaborate documentation, record keeping is now expected practice, even on smaller works.

Each party should keep copies of:

• Design documents and specifications

• Appointment letters (or written declinations)

• Notes evidencing coordination between designers and contractors

• Risk management information relevant to compliance

• Completion documents for Building Control sign-off

Although the “Golden Thread” is mandatory only for HRBs, its principles — transparency, traceability, and accountability — are now encouraged across the board.

Gateway Influence on Domestic Projects

Although formal Gateways under the BSA apply only to HRBs, the design scrutiny and pre-construction documentation expectations are increasing even for small works.

Expect Building Control bodies to request:

• Fully coordinated drawings and specifications

• Early justification of compliance (especially structural, fire, thermal and access requirements)

• Clear identification of who is acting as PD and PC

Projects with vague, fragmented or late-stage information are more likely to suffer delays or incur compliance queries.

Sanctions and Enforcement

Failing to comply with the above responsibilities may result in:

• Refused or delayed Building Control sign-off

• Enforcement Notices under Section 36 of the Building Act 1984

• Criminal liability for serious breaches

• Professional negligence claims if designers or contractors fail in their legal duties

How Shepherd Gilmour Can Help

At Shepherd Gilmour, we routinely support clients, designers, and builders in navigating the Building Regulations for domestic projects.

We can assist by:

• Providing formal appointment or declination letters for PD/PC roles

• Delivering full structural design packages and calculations for Building Control

• Conducting coordination reviews across design and construction

• Supporting dutyholders with compliance documentation and risk reviews

By formalising roles and offering expert guidance, we reduce your risk and ensure your project proceeds smoothly and compliantly.

Summary: Key Takeaways

• Homeowners are always legally the client — but their duties are automatically discharged to the first appointed Designer and/or Contractor unless appointments are made or declined in writing

• Designers become Principal Designer by default unless they formally opt out

• Contractors become Principal Contractor by default, but only if competent

• Principal Contractors & Designers should ensure their Insurance is valid

• Contractors cannot be Principal Designers unless they carry out design

• Competency, documentation, and coordination are non-negotiable in the current regime

Need advice on dutyholder responsibilities or compliance?

 Contact us via:

🌐 Website

📧 info@shepherdgilmour.co.uk

📞 0113 245 0555

We’re here to ensure your domestic project is both safe and regulation-ready.

Suggested Further Reading & Useful Material

1. The Building Regulations 2010 (Latest Available)

2. Manual to The Building Regulations