UK Building Regulations are the legal framework that governs how buildings are designed and constructed. For MEP engineers, several Approved Documents directly affect your work.
The ones that matter most to MEP
Part L (Conservation of fuel and power) — U-values, SFP limits, insulation standards, energy targets. The document that drives most mechanical design decisions.
Part F (Ventilation) — Minimum ventilation rates, system requirements, duct sizing implications. Refer to the current edition for rates and compliance routes.
Part G (Sanitation, hot water and water efficiency) — DHW storage, temperature requirements, water efficiency.
Part J (Heat producing appliances) — Flue design, combustion air, boiler rooms.
Part B (Fire safety) — Fire dampers, smoke extract, compartmentation affecting services.
Part P (Electrical safety) — BS 7671 relationship, certification requirements.
Approved Documents vs the Regulations
The ADs are guidance, not law. You can use alternative approaches if you can demonstrate compliance. But in practice, following the AD is the accepted route.
How they interact with standards
Building Regs set the legal requirement. CIBSE Guides and British Standards provide the methodology to achieve compliance. Example: Part L requires SFP below certain limits; CIBSE Guide B tells you how to design the system; BS EN 13779 defines the measurement method.
Keeping up to date
Regulations change. Part L was updated in 2021. Part F was updated in 2022. Engineers must check they're working to the current edition.
Use the Standards Picker to find exactly which regulations and standards apply to your project type.