Part A (Structure)

Complete 2026 UK guide to Part A Building Regulations: structural loading, foundations, ground movement, walls, floors, roofs, chimneys, disproportionate collapse and Building Control evidence.

What Is Approved Document A?

Approved Document Ais the UK Government’s statutory guidance for meeting the structure requirements of the Building Regulations in England. It explains how building work should be designed and constructed so that loads are safely carried, ground movement is properly considered and buildings have suitable robustness against accidental actions.

In simple terms, Part A is the part of the Building Regulations that asks: will the building stand up, will it transfer loads safely to the ground, and will the work avoid making another building unsafe? It applies to new homes, extensions, loft conversions, alterations, structural openings, foundations, roofs, floors, masonry walls, chimneys and many small domestic projects where homeowners do not always realise structural evidence may be required.

2026 Accuracy Note

As of 2026, GOV.UK still listsApproved Document A: Structureas the statutory guidance published in September 2013. This page is therefore a current 2026 guide to the in-force guidance, not a claim that a separate 2026 edition of Approved Document A has been issued.

Approved Documents are guidance, not the only legal way to comply. The legal duty is to satisfy the functional requirements in Schedule 1 of the Building Regulations. However, following the practical guidance in the Approved Documents is the most common route used by homeowners, designers, builders, structural engineers and Building Control bodies for standard domestic and small commercial work.

A1 — Loading

Requires the building to safely sustain and transmit dead, imposed, wind, snow and other loads to the ground without instability, excessive deflection or collapse.

A2 — Ground Movement

Requires the building to remain stable when ground conditions, shrinkable clay, trees, made ground, drains or site movement could affect foundations.

A3 — Robustness

Requires certain buildings to be designed so that a local failure does not lead to disproportionate collapse of a much larger part of the structure.

Approved Document A Summary — A1, A2 and A3

Part A is split into three core requirements. For many domestic projects, A1 and A2 are the day-to-day requirements: beams must be correctly sized, walls must be properly supported, foundations must be suitable for the soil, and loads must be carried safely from roof to foundation. A3 becomes especially important for larger, taller, multi-occupancy or non-standard buildings.

• Requirement: A1 Loading; What It Covers: Dead loads, imposed loads, wind, snow, lateral restraint, beams, floors, roofs and load paths.; Common Projects: Steel beams, lintels, loft floors, roof alterations, wall removals, extensions.; Typical Evidence: structural design checks, beam schedules, drawings, padstone details and inspection records.
• Requirement: A2 Ground Movement; What It Covers: Foundations, soil conditions, ground heave, subsidence, clay shrinkage, tree influence and stability of supporting ground.; Common Projects: New foundations, extensions, garages, retaining walls, works near trees or drains.; Typical Evidence: Foundation design, trial pits, site investigation, engineer notes and Building Control inspections.
• Requirement: A3 Disproportionate Collapse; What It Covers: Robustness against accidental actions so a local failure does not cause an excessive collapse.; Common Projects: Flats, taller buildings, commercial structures, certain multi-storey residential buildings.; Typical Evidence: Robustness strategy, tying details, load-bearing wall design and engineer certification.

Practical Rule

If your work changes how loads are carried — for example by removing a wall, adding a beam, altering a roof, building over drains, changing foundations or creating a loft floor — treat Part A evidence as essential, not optional.

A1 Loading — How Buildings Carry Weight Safely

A1 is the structural stability requirement most homeowners encounter. It covers the ability of a building to carry loads safely during use and transmit those loads down to the ground. Loads are not only the weight of bricks and concrete. A building must also account for people, furniture, stored items, roof coverings, snow, wind pressure, suction, lateral forces, accidental actions and any extra load added by future finishes or services.

The important idea is theload path. A roof load should transfer to rafters or trusses, then to walls or beams, then to foundations, then to suitable ground. If a load-bearing wall is removed, that load path is interrupted. A correctly sized beam, padstone, pier, column or foundation must take over the work of the wall that was removed.

Common A1 Checks

• Dead load:the permanent weight of the structure, including concrete, masonry, floors, roof tiles, screed and fixed finishes.
• Imposed load:variable loading from occupants, furniture, storage, vehicles, maintenance access and use of rooms.
• Wind and snow:environmental loads that affect roof design, lateral bracing, gable stability and exposed buildings.
• Deflection:beams and joists must not sag excessively even if they do not fail structurally.
• Bearing:beams need adequate end bearing on masonry, padstones, posts or steel columns.
• Lateral restraint:walls, floors and roofs often work together; removing one element can reduce restraint elsewhere.

For simple domestic work, Building Control may accept standard details where they are clearly within the limits of Approved Document A. However, once spans, loads, openings, unusual roof forms, old masonry, chimney breasts, vaulted ceilings or large glazing are involved, structural design checks from a competent structural engineer are normally the safest route.

Wall Removal Warning

Never remove a wall because it “looks non-structural”. Walls can support floors, roof members, lateral restraint, chimney loads or masonry above. Always confirm with a competent person before cutting, propping or demolition.

A2 Ground Movement — Foundations, Soil and Site Conditions

A2 requires the building to be constructed so that ground movement will not impair stability. In practical terms, the foundation must be suitable for the soil, trees, drains, slope, groundwater, previous development and the loads from the building above. A foundation that works on dense gravel may fail on shrinkable clay, made ground or land affected by old trees.

For a normal extension, Building Control will usually inspect the foundation trench before concrete is poured. The inspector checks ground conditions, depth, width, nearby drains, tree influence and whether the bearing stratum appears suitable. If ground is poor or uncertain, deeper trench-fill foundations, reinforced foundations, rafts, piles or engineered solutions may be required.

Ground Conditions That Increase Part A Risk

• Clay soil:shrinkable clay can swell and shrink as moisture changes, especially near trees.
• Nearby trees:roots can remove moisture from soil; removed trees can also cause heave as moisture returns.
• Made ground:filled or previously developed land may be inconsistent and unsuitable for simple strip foundations.
• Sloping sites:level changes create lateral pressure and may require retaining design.
• Drains and services:foundations near drains need careful detailing to avoid undermining or future settlement.
• Mining or chalk risk:abnormal ground needs specialist investigation and possibly engineered foundations.

ConcreteMath guides can help you estimate foundation volume, trench fill, concrete orders and sub-base quantities, but they do not replace ground assessment. A correct concrete quantity does not prove the foundation is structurally suitable. The depth, width, reinforcement and foundation type must be agreed with Building Control or designed by an engineer where conditions demand it.

Trial Pits

Expose existing foundation depth, soil type and nearby drains before designing an extension or structural alteration.

Tree Influence

Tree species, distance, mature height and clay soil can change foundation depth and may trigger heave protection.

Soil Investigation

Made ground, soft ground, mining risk or unusual settlement history may require professional site investigation.

A3 Disproportionate Collapse — Robustness and Accidental Actions

A3 deals with disproportionate collapse: a situation where a relatively small local failure causes a much larger part of a building to collapse. The requirement is most relevant to taller, multi-storey, multi-occupancy and non-domestic buildings, but it can also matter when structural walls are changed in flats or when load paths are complex.

For typical small houses, compliance is often achieved through conventional masonry, floor and roof construction within the guidance limits. For flats, commercial buildings, larger buildings or structures with unusual load-bearing arrangements, an engineer may need to demonstrate robustness through tying, continuity, alternative load paths or key element design.

Why A3 Matters

• A building should not be so fragile that a small accidental event causes a progressive collapse.
• Structural ties can help floors, walls and columns work together under abnormal conditions.
• Removing structural walls in flats can affect not only one unit but the load path of the wider building.
• Multi-storey buildings may need a clearly documented robustness strategy, not just individual beam working.

Associated Guidance

The Planning Portal lists associated Part A documents covering disproportionate collapse, masonry robustness, sulfate damage, multi-storey car park edge protection and boundary/retaining wall safety. These are useful when a project goes beyond standard domestic construction.

Part A for Common UK Projects

Most people search for Approved Document A because they are planning a specific job: an extension, a wall removal, a loft conversion, a new garage or a retaining wall. The same structural principles apply, but the evidence required changes with complexity.

• Project: Single-storey extension; Part A Issues: Foundation depth, ground conditions, cavity walls, roof load, lateral restraint.; Common Evidence: Drawings, foundation inspection, lintel/beam details, concrete volume records.; Risk Level: Standard
• Project: Two-storey extension; Part A Issues: Higher loads, deeper foundations, wall stability, roof/floor load paths.; Common Evidence: Full drawings, engineer working, foundation design, inspection sign-off.; Risk Level: Higher
• Project: Load-bearing wall removal; Part A Issues: Beam size, end bearing, padstones, temporary works, residual stability.; Common Evidence: structural design checks, beam specification, padstone details, inspection before covering.; Risk Level: Higher
• Project: Loft conversion; Part A Issues: New habitable floor loading, roof alterations, steel beams, existing wall capacity.; Common Evidence: Engineer working, floor joist design, roof support details, stair opening design.; Risk Level: Higher
• Project: Garage / outbuilding; Part A Issues: Foundations, wall thickness, roof restraint, ground slab and wind stability.; Common Evidence: Standard details if small and simple; working if large, tall or close to boundaries.; Risk Level: Variable
• Project: Retaining wall; Part A Issues: Earth pressure, water pressure, sliding, overturning, bearing failure, drainage.; Common Evidence: Structural engineer design, drainage detail, reinforcement schedule, inspection.; Risk Level: Specialist

Structural Elements Covered by Approved Document A

Approved Document A covers the main structural elements of a building: foundations, walls, floors, roofs and chimneys. Each element has to be considered individually and as part of a whole building system. A beam may be strong enough in isolation, but if it bears onto weak masonry, an undersized padstone or an inadequate foundation, the overall structure may still fail.

Foundations

Foundations carry the building load to the ground. For small domestic projects they are often strip or trench-fill concrete. Depth and width depend on soil type, loads, nearby trees, drains, frost, made ground and site history. Building Control inspections before pouring concrete are a critical part of proving compliance.

Walls and Masonry

Walls support vertical loads and often provide lateral stability. Part A guidance includes wall thickness, height, length, openings, buttressing, cavity construction, piers and masonry design rules. Large openings, slender piers and heavily loaded walls usually need engineer measurement.

Floors

Floors must support imposed loads, resist excessive deflection and transfer loads to walls or beams. Timber floors, beam-and-block floors and concrete slabs all need correct spans, bearings, insulation build-up, damp protection and support conditions.

Roofs

Roofs must resist dead load, snow load, wind uplift and lateral spread. Altering roof timbers, converting lofts, removing struts or installing large rooflights can change the roof’s structural behaviour. Prefabricated trusses should not be cut without specialist design.

Chimneys

Chimneys and chimney breasts are often load-bearing or stability elements in older properties. Removing a chimney breast without properly supporting the remaining masonry above can create serious instability. Building Control and party wall issues commonly apply.

structural design checks, Drawings and Building Control Evidence

Building Control approval is not just about submitting a plan. The inspector needs enough evidence to be satisfied that the work will comply with the Building Regulations. For structural work, that evidence is normally a combination of drawings, working, specifications, site inspections and sometimes photographs or certificates.

A structural working pack typically includes the design assumptions, material strengths, beam or joist sizes, load working, bearing details, padstone sizes, connection details and references to relevant standards. Drawings should show exactly where structural elements are installed, how they are supported and what must be inspected before being covered.

Drawings

Show foundation layout, beam locations, load-bearing walls, openings, bearings, roof changes and construction build-up.

Working

Demonstrate beam, joist, wall, foundation or retaining structure capacity under the required load combinations.

Inspections

Building Control may inspect excavation, reinforcement, beam bearing, damp proofing, floor structure and completion details.

Do Not Cover Structural Work Too Early

Beams, padstones, foundations, floor joists and reinforcement may need inspection before plasterboard, screed, concrete or finishes hide them. If work is covered too soon, Building Control may ask for exposure, photographs or additional evidence.

England, Wales, Scotland and Northern Ireland — Which Rules Apply?

Approved Document A on GOV.UK is guidance for Building Regulations in England and certain excepted energy buildings in Wales. Wales, Scotland and Northern Ireland have their own building standards systems and guidance documents. The principles of structural safety are similar across the UK, but the exact route, terminology and responsible authority can differ.

• England:Approved Document A is the primary guidance route for Part A structure compliance.
• Wales:Welsh Government publishes Building Regulations guidance; always check the Welsh approved documents for projects in Wales.
• Scotland:Scotland uses Scottish Building Standards Technical Handbooks rather than the English Approved Documents.
• Northern Ireland:Northern Ireland has separate technical booklets and Building Control arrangements.

For SEO and practical use, many homeowners search “UK Building Regulations Part A”. On a real project, however, the location of the building matters. Always use the guidance for the nation where the work is taking place and confirm with the relevant Building Control body.

2026 Checklist Before Starting Structural Work

Use this checklist before ordering concrete, steel, blocks, lintels, roof timbers or foundation materials. It will help reduce rework, delays and disputes with Building Control.

• Confirm whether the work is structural or affects structural stability.
• Identify all loads being carried: roof, floor, wall, chimney, retained ground, wind and snow.
• Check existing foundations, wall thicknesses, spans, masonry quality and bearing points.
• Carry out trial pits where foundations or ground conditions are uncertain.
• Get structural design checks for beams, large openings, loft conversions, retaining walls and non-standard foundations.
• Submit drawings and working using the appropriate Building Control route.
• Agree inspection stages before work starts.
• Do not substitute beam sizes, concrete grades, reinforcement, blocks or padstones without approval.
• Keep records: photos, delivery tickets, concrete quantities, inspection notes and certificates.
• Use ConcreteMath resources for planning quantities, but rely on Building Control/engineer design for compliance decisions.

Best Practice

For structural work, “measure twice and pour once” is cheaper than trying to fix a failed inspection. Correct drawings, working and inspection timing usually save more money than they cost.

Part A vs Planning Permission — Do Not Confuse the Two

Planning permission and Building Regulations approval are separate systems. Planning permission normally deals with the external impact of development: size, appearance, overlooking, highways, conservation areas, permitted development limits and land-use policy. Part A Building Regulations deal with structural safety: whether the building work is stable, properly supported and safe to use. A project can be permitted under planning rules but still fail Building Regulations if the foundations, beams or walls are not structurally adequate.

This distinction is especially important for extensions and internal alterations. A small rear extension may not require a full planning application if it falls within permitted development, but the foundations, walls, roof and drainage still need Building Regulations compliance. Similarly, removing a load-bearing wall inside a house may not need planning permission, but it normally requires Building Control approval and structural design checks.

Typical Examples

• Permitted development extension:may avoid planning permission, but Part A still applies to foundations, walls, roof and openings.
• Internal open-plan kitchen:may not affect planning, but a wall removal can require steel beam working.
• Loft conversion:may fall within permitted development, but Part A applies to new floor loads, roof structure and existing walls.
• Garden retaining wall:may appear minor, but retained ground and public safety can make structural design essential.

Key Point

Do not start structural work just because planning permission is not required. Always check the Building Regulations position and speak to Building Control where the work affects loads, foundations, walls, floors, roofs or stability.

Materials, Workmanship and Structural Quality

Approved Document A does not stand alone. Structural safety also depends on the correct materials, workmanship and installation. A beam working is only useful if the beam delivered to site matches the specified grade and size. A foundation design is only reliable if the trench is excavated to the approved depth, loose material is removed, concrete is placed correctly and any reinforcement is installed with the required cover.

For masonry construction, block strength, mortar designation, wall ties, cavity width, pier sizes, lintel type and bearing length all affect structural performance. For timber floors and roofs, joist grade, spacing, restraint straps, hangers, fixings and notching rules matter. For concrete work, the concrete grade, volume, curing, reinforcement, depth and ground preparation must match the intended design.

Common Site Mistakes That Create Part A Problems

• Ordering a different steel beam because it is cheaper or easier to source.
• Using an undersized padstone or bearing a beam directly onto poor masonry.
• Pouring foundation concrete before Building Control has inspected the trench.
• Cutting roof trusses or purlins to fit a loft opening without engineer approval.
• Using blocks or mortar that do not match the structural specification.
• Failing to install lateral restraint straps at the required locations.
• Covering joists, beams, reinforcement or bearings before inspection.

A good contractor will work from the latest approved drawings, check deliveries against the specification and ask before substituting products. Where a change is necessary, the designer, engineer and Building Control should agree it before it is built in. This is particularly important when availability, cost pressure or site access encourages last-minute substitutions.

Building Control Application Routes for Structural Work

In England, domestic structural work is usually handled through either a local authority Building Control team or a registered building control approver. The two common application routes are Full Plans and Building Notice. The right route depends on complexity, risk and how much certainty you want before work starts.

Full Plans Route

A Full Plans application means detailed drawings, structural design checks and specifications are submitted before work begins. Building Control checks the design and can issue comments or conditional approval. This route is strongly recommended for larger extensions, loft conversions, structural openings, new dwellings and projects with complex foundations. It gives clearer evidence before materials are ordered and reduces the risk of expensive changes during construction.

Building Notice Route

A Building Notice can be quicker for simple domestic work, but it gives less pre-start design certainty. You still need to demonstrate compliance during the work, and Building Control can ask for working or changes if the structure is not clearly adequate. For beam installations, wall removals and foundations on uncertain ground, a Building Notice should not be used as a shortcut around proper structural design.

Full Plans

Best for complex work because drawings and working are checked before construction starts.

Building Notice

Useful for simpler domestic work, but evidence can still be requested during inspections.

Completion Certificate

Keep the certificate with property records, especially for future sale, insurance and remortgage checks.

Whichever route you choose, completion records matter. Solicitors and surveyors often ask for Building Regulations certificates during a sale. Missing structural records can delay conveyancing, trigger indemnity discussions or reduce buyer confidence, especially where walls have been removed or loft rooms added.

When Part A Needs Specialist Structural Engineering

Some projects are outside the comfort zone of standard domestic guidance. In these cases, relying on generic span tables, builder experience or online rules of thumb is risky. Specialist engineering is usually needed where the structure is unusual, the loads are high, the consequences of failure are serious or the existing building is old, altered or poorly documented.

• Large open-plan spaces:long-span beams, hidden supports and complex load paths often require steel frame or goalpost design.
• Basements and excavations:temporary works, retaining walls, groundwater and neighbouring foundations make specialist design essential.
• Flats and multi-occupancy buildings:changes can affect shared structure and disproportionate collapse strategy.
• Old or listed buildings:timber decay, shallow foundations, lime mortar and historic alterations require careful assessment.
• Retaining walls:retained soil, surcharge, water pressure and drainage must be determined, not guessed.
• Subsidence or previous movement:cracks, underpinning history, tree claims or mining risk require professional investigation.
• Heavy loads:hot tubs, roof terraces, balconies, large aquariums, vehicle loads and plant rooms can exceed normal domestic assumptions.

The role of the engineer is not simply to “get a beam size”. A competent engineer checks load paths, stability, serviceability, bearings, connections, materials and constructability. On more complex projects they may also specify temporary works, sequencing, inspections and limits on what can be removed before new supports are installed.

Safety First

Temporary propping is part of structural safety. Even if the final beam is correctly sized, unsafe demolition sequence or inadequate temporary support can cause collapse before the permanent structure is installed.

Professional Disclaimer

This guide explains Approved Document A for planning and education. It is not a structural design, engineering certificate, Building Control approval or site-specific safety assessment. For beams, foundations, retaining walls, loft conversions, subsidence risk or multi-storey work, use a competent structural engineer and speak to Building Control before construction.

Approved Document A FAQs

Common questions about Part A structure compliance, structural design checks, foundations, beams, wall removal and Building Control in the UK.

Related UK Building Regulation & Concrete Resources

Use these linked ConcreteMath resources to plan quantities and understand the practical material side of structural work. Always pair quantity guides with approved structural design where Part A applies.

For related building and design resources, you can also visit ArchitectsEmporium.com.