UK Building Regulations Approved Documents

The statutory requirement covering structural safety of buildings in England and Wales. Approved Document A sets out acceptable methods for meeting Part A: foundation design (type, depth, width, concrete grade), wall and roof structural calculations, stability against disproportionate collapse, and combined dead/imposed/wind loading. For extensions, Part A governs the minimum 1m foundation depth to firm ground, trench fill vs strip foundation rules, and steelwork specifications. Your structural engineer designs to Part A and building control checks against it.

The part of the Building Regulations covering fire safety: means of escape, fire spread within and between buildings, and access for the fire service. For extensions it governs matters such as escape windows, protected stairways and how close to a boundary certain roof coverings can sit.

Site preparation and resistance to contaminants and moisture

Building regulations covering toxic substances released by building materials. The single substantive requirement (D1) prohibits insulating materials that release formaldehyde gas in concentrations harmful to occupants. Rarely engaged on modern domestic extensions because mainstream insulation products are already compliant, but remains the statutory hook if a non-standard insulating material is proposed.

The part of the Building Regulations covering resistance to the passage of sound, setting sound insulation standards mainly between dwellings and for separating walls and floors. It is most relevant to conversions and new separating elements.

The part of the Building Regulations covering ventilation, setting the background and purge ventilation a habitable space needs to control moisture and air quality. It is closely tied to Part L, because making a building more airtight raises the importance of adequate ventilation.

Sanitation, hot water safety and water efficiency

Building regulations governing drainage and waste disposal in England. Specifies waste pipe gradients (18–90mm fall per metre for 40mm pipes), trap requirements, foul drainage construction (granular bedding to BS EN 1610), and the four-step priority hierarchy for surface-water discharge (soakaway, watercourse, surface water sewer, combined sewer). Building control inspects drainage runs and connections against Part H before backfill.

Building regulations covering combustion appliances (boilers, stoves, fires) and fuel storage systems. Sets boiler flue siting requirements including minimum distances from windows, doors, boundaries, ground level, and roof openings; carbon monoxide alarm requirements for solid fuel and biomass installations; hearth, chimney and flue construction; and oil/LPG fuel storage tank separation distances.

Protection from falling, collision and impact. In England (since April 2013), Part K also absorbed the glazing safety requirements that previously sat in Part N — covering safety glazing in critical locations, opening/cleaning of windows, and impact protection.

Conservation of fuel and power (energy efficiency)

The part of the Building Regulations covering access to and use of buildings, including level thresholds, door widths and accessible facilities. A new extension should not make a dwelling less accessible than it was before.

Approved Document N (Glazing — safety in relation to impact, opening and cleaning) was withdrawn in England in April 2013 when its requirements were absorbed into Approved Document K. Wales has not adopted this change: Part N remains a standalone Approved Document in Wales, governing safety glazing in critical locations (below 800mm in walls, in doors, in side panels), the safe opening and cleaning of windows, and impact protection. Homeowners and builders in Wales must refer to AD N rather than AD K for glazing safety requirements.

Building regulations introduced in June 2022 limiting summer overheating in new residential buildings in England. Applies primarily to new dwellings and material change of use to residential, not generally to extensions of existing dwellings. Sets two compliance routes: a simplified method based on glazing area, ventilation openings and shading, or a dynamic thermal modelling method (CIBSE TM59). Building control checks Part O at design stage for in-scope projects.

The electrical safety section of the Building Regulations for England and Wales. Makes any new circuit, consumer unit replacement, and work in special locations (for example bathrooms and kitchens) notifiable. Compliance must be certified either by a competent-person-scheme registered installer (NICEIC, NAPIT, ELECSA), a third-party certifier, or by direct building control notification before work starts. Non-compliant work becomes a legal issue at sale, mortgage and insurance time, not just a technical breach.

Approved Document Q requires easily accessible windows and doors in new dwellings to meet PAS 24:2016 security standard. Glazing within 400mm of door locks must meet BS EN 356:2000 P1A.

Building regulations requiring new buildings (and major renovations) to be equipped with in-building physical infrastructure capable of carrying high-speed electronic communications, and a dedicated access point. Applies on a building-by-building basis: typically engaged for new dwellings, and for major renovations involving the building envelope, but not usually for ordinary domestic extensions. Implements the EU Broadband Cost Reduction Directive in England.

Building regulations introduced in June 2022 requiring electric vehicle charge points to be installed on most new dwellings, dwellings undergoing major renovation that have associated parking, and new non-residential buildings with parking. For domestic extensions the trigger is whether the work creates a new associated parking space; ordinary rear extensions to an existing house do not normally engage Part S, but garage conversions or driveway works that change parking provision can. England-only.

Building regulations effective 1 October 2024 governing the provision of toilet accommodation in non-domestic buildings: minimum proportions of universal toilets, separate-sex facilities, and ambulant accessible WCs in new and materially altered non-domestic buildings. Does not apply to dwellings, so out of scope for ordinary domestic extensions. Included in the graph for completeness when the site covers commercial conversions or mixed-use schemes.

The cross-cutting Approved Document supporting Regulation 7 of the Building Regulations 2010. Requires that building work is carried out with adequate and proper materials (appropriate for the circumstances, adequately mixed or prepared, applied/used/fixed so as to perform the functions for which they are designed) and in a workmanlike manner. Applies to every other Approved Document — building control can refuse sign-off on workmanship grounds even when individual Part requirements are technically met. Volume 2 covers fire-related restrictions on combustible materials in external walls.

The umbrella reference document published by DLUHC/MHCLG that explains how the Building Regulations 2010 and the suite of Approved Documents fit together. Sets out which works are notifiable, how the building control process operates (full plans vs building notice), the role of competent person schemes, and how the individual Approved Documents (A through to S, plus AD7) interact. Useful starting point for homeowners or self-managers needing to understand which Parts apply to a given project before drilling into the individual ADs.