Summary
- Over 90% of UK domestic extensions, loft conversions and small commercial projects are non-HRBs — under 18 metres and fewer than 7 storeys — so the HRB Gateway process does not apply to them.
- But the Building Safety Act 2022 dutyholder regime does apply: on every project subject to Building Regulations, a Principal Designer (BSA) must plan, manage and monitor design work for compliance — and on domestic projects, the principal designer role can fall on the designer in control of the design phase by operation of law, without a written appointment and without a fee.
- This library covers every Approved Document (Parts A–T) with non-HRB compliance guides for small practices, plus a plain-English comparison of BSA and CDM Principal Designer duties.
What changed for small practices on 1 October 2023
The Building Regulations etc. (Amendment) (England) Regulations 2023 brought the Building Safety Act 2022 dutyholder regime into force for all building work in England — not just high-rise. Every project subject to Building Regulations now has a client, designers and contractors with defined legal duties, and where there is more than one contractor, a Principal Designer (BSA) and Principal Contractor (BSA) must be appointed in writing.
The trap for small practices is the domestic default. For multi-contractor projects, where a domestic client fails to make the required written appointments, regulation 11C(2) provides that the designer in control of the design phase is the principal designer — you can hold the role without ever agreeing to it, and without pricing for it. For single-contractor projects, the position differs: the contractor is treated as principal contractor (regulation 11D(6)); if there is only one designer, that designer must fulfil the principal designer duties; if there is more than one designer they must agree in writing which of them does so (regulation 11D(7)).
The duty itself is coordination: take all reasonable steps to ensure the design, if built, would comply with all relevant requirements of the Building Regulations — the functional requirements set out in Approved Documents Parts A to T. That is why an evidence trail per Part, per project, is the working core of BSA compliance for a small practice.
Non-HRB vs HRB: why the distinction matters
Most national BSA commentary is written for high-rise residential towers. If your workload is extensions, lofts, one-off houses and small commercial refurbishments, the Gateway articles do not apply to you — but the Principal Designer duties, competence requirements and Parts A–T compliance coordination absolutely do.
| Aspect | Non-HRB project (this library) | Higher-Risk Building (HRB) |
|---|---|---|
| Definition | Under 18 m and fewer than 7 storeys; not a hospital or care home meeting the height test | ≥18 m or ≥7 storeys with 2+ residential units, or hospital/care home meeting the test |
| Approval route | Local authority or Registered Building Control Approver | Building Safety Regulator, Gateways 1–3 |
| Gateway process | Does not apply | Mandatory hard stops at planning, pre-construction and completion |
| Dutyholder regime (PD/PC) | Applies in full | Applies, with additional HRB-specific duties |
| Golden thread | No formal statutory golden thread, but evidence of compliance is expected | Statutory golden thread of building information |
How to use this hub
This is the home page for PD Pathway's non-HRB Building Regulations compliance library. Each card below opens a full guide to one Approved Document: what the Building Safety Act 2022 requires on non-HRB jobs, the design risks and evidence needed at RIBA Stages 2–4, the standards to cite, and the pitfalls that catch out sole practitioners.
- Starting a project? Use the quick-reference table below to see which Parts your project type typically engages, then open those guides.
- New to the BSA dutyholder regime? Read the featured BSA vs CDM comparison first — it untangles the two Principal Designer roles that share one name.
- Building your evidence file? Every Part guide ends with the records to keep — or let PD Pathway track them for you automatically.
Featured companion read
BSA vs CDM Principal Designer Duties: What's the Difference on Non-HRB Projects? The difference between the Building Safety Act 2022 and CDM 2015 Principal Designer roles — legal basis, triggers, domestic client defaults and competence requirements in one clear comparison table. Read the comparison →Approved Documents Parts A–T: non-HRB compliance guides
All 18 Approved Documents in force in England (there is no Part I or Part N), grouped by theme and each covered for non-HRB domestic and small commercial work.
Structure & Fire
The two Parts with the highest stakes on any project — load paths and life safety.
Health & Comfort
Moisture, air, sound, water, waste and heat — the fabric-of-daily-life requirements.
Energy & Sustainability
Fabric performance and future-ready infrastructure for energy, broadband and EVs.
Access & Safety
Getting into, moving around and safely using the building — stairs, access, electrics, security and sanitary provision.
Which Parts apply to typical non-HRB projects?
Almost every project engages Parts B and L; the table below shows the Parts that most commonly drive design decisions and evidence on typical small-practice work. It is a starting point, not a substitute for a project-specific relevant-requirements review.
| Project type | Parts that typically apply |
|---|---|
| Loft conversion | A (new steels), B (protected escape route), E (sound between rooms), F (ventilation), K (stair pitch and headroom), L (roof insulation), P (new circuits) |
| Rear or side extension | A (openings and lintels), B (fire spread), C (DPC and ground moisture), F (ventilation), H (drains and build-over), L (U-values and photo evidence), P (electrics) |
| Garage conversion | B (fire separation), C (floor damp-proofing), E (sound to habitable rooms), F (background ventilation), L (upgrading the fabric), P (electrics) |
| Kitchen or bathroom refit | F (extract ventilation), G (hot water safety and efficiency), H (waste connections), P (notifiable electrical work) |
| New-build dwelling | Every Part applies — including O (overheating), Q (security), R (broadband), S (EV charging) and M4(1) access |
| Small commercial refurbishment | B (means of escape), K (guarding and glazing), L Volume 2, M Volume 2 (access), T (toilet accommodation, 2024) |
Frequently asked questions
Do Principal Designer (BSA) duties really apply to a small house extension?
Yes. The BSA 2022 dutyholder regime applies to all work subject to Building Regulations in England, regardless of size. On a domestic project with more than one contractor, a Principal Designer must be appointed in writing — and if the client does not appoint one, the principal designer role falls on the designer in control of the design phase under regulation 11C(2). The client's own Building Regulations duties pass to the contractor or principal contractor under regulation 11C(1) — not to the designer. On single-contractor projects, the contractor is treated as principal contractor and the designer (or designers by written agreement) must address the principal designer duties under regulation 11D(6)–(7).
What is a non-HRB?
A non-higher-risk building: one that is under 18 metres in height and has fewer than 7 storeys, and is not a hospital or care home meeting the height threshold. Non-HRB projects avoid the Building Safety Regulator's Gateway process entirely, but the dutyholder regime and Parts A–T compliance duties still apply.
Is the golden thread required on non-HRB projects?
The statutory golden thread applies to HRBs. On non-HRB work there is no formal golden-thread duty, but the Principal Designer must still be able to demonstrate that design work was planned, managed and monitored for Building Regulations compliance — which in practice means keeping a structured evidence record per Approved Document.
Track this natively instead of in Word templates
PD Pathway gives small practices an automated Parts A–T relevant-requirements tracker, stage-by-stage Principal Designer checklists and one-click compliance documents — built strictly for non-HRB projects. First project free, then from £10 per project or £99/yr unlimited.