Quick summary: Building Regulations Part A
Building Regulations Part A deals with structural safety. For homeowners, this usually means making sure foundations, walls, floors, roofs, beams, openings and structural alterations are designed and built safely, so the building can carry loads without movement, collapse or damage to nearby buildings.
- Part A1 covers loading, including the weight of the building, people, furniture, snow, wind and other forces.
- Part A2 covers ground movement, including foundation design and risks from soil, trees, shrinkage, heave and subsidence.
- Part A3 covers disproportionate collapse, mainly relevant where a failure in one part of a building could cause a much wider collapse.
- Most homeowner projects involving extensions, loft conversions, wall removals or structural openings need Building Control approval and, often, structural calculations.
In simple terms, Part A is the part of the Building Regulations that helps prove your project will stand up safely, both during construction and once the work is complete.
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What is Building Regulations Part A?
Building Regulations Part A is the section of the Building Regulations that deals with structural safety. It is concerned with whether a building, extension or alteration can safely support the loads placed on it without becoming unstable, moving excessively, or affecting another building.
For homeowners, Part A often becomes relevant when you are building an extension, converting a loft, removing a load-bearing wall, adding large steel beams, forming new openings, changing the roof structure, or building close to existing foundations.
Approved Document A is the government guidance that explains one accepted route to meeting the structural requirements of the Building Regulations. However, the legal duty is to comply with the Building Regulations themselves, not simply to “tick off” a document. In practice, Building Control will usually expect clear drawings, structural calculations and site inspections where structural work is involved.
This article is a Support Stone for our wider complete homeowner guide to Building Regulations, which explains how Building Control approval works across all the main Parts.
Building Regulations Part A1: loading explained
Part A1 is about making sure the structure can safely carry loads and transfer them down to the ground. That sounds technical, but the principle is simple: every part of the building has to be strong enough for what it supports.
What loads does Part A consider?
A structure may need to deal with several different types of load, including:
- Dead loads – the permanent weight of the structure, such as walls, floors, roof coverings and finishes.
- Imposed loads – people, furniture, storage, appliances and normal use of the building.
- Wind loads – pressure and suction on walls, roofs and structural frames.
- Snow loads – extra weight on roofs during bad weather.
- Construction loads – temporary loads while the work is being built.
Common homeowner examples of Part A1
In everyday home projects, Building Regulations Part A1 often comes up where:
- a rear wall is opened up for bifold or sliding doors,
- a chimney breast is removed,
- a loft floor is strengthened for habitable use,
- a steel beam is needed over a new opening,
- a new roof structure is created for a dormer or extension,
- an internal wall is removed to create an open-plan kitchen-diner.
Building Regulations Part A2: ground movement and foundations
Part A2 is about making sure ground movement does not make the building unstable. This is especially important for foundations, because even a well-designed wall or beam can fail if the ground below it moves or settles unevenly.
Why ground movement matters
Ground conditions vary from site to site. Clay soils, trees, filled ground, sloping sites, drains, nearby structures and previous excavation can all affect foundation design. Therefore, two extensions that look identical on paper may need different foundations in practice.
Building Control will usually want to know that foundations are suitable for the soil and the loads above. On many small domestic projects, foundation trenches are inspected on site before concrete is poured. If the inspector finds soft ground, tree influence or unexpected conditions, deeper or wider foundations may be required.
Where Part A2 affects extensions
- Single-storey extensions may need deeper foundations near trees or drains.
- Two-storey extensions usually place greater loads on the ground, so foundation design becomes more important.
- Building near boundaries can affect neighbouring foundations and may also trigger Party Wall considerations.
- Older homes may have shallow foundations, which need careful consideration when adding new loads nearby.
Building Regulations Part A3: disproportionate collapse
Part A3 deals with disproportionate collapse. In simple terms, this means a building should not suffer a collapse that is out of proportion to the original cause.
For typical small householder projects, this is usually less visible than foundations, walls and beams. However, it can become more relevant where the project affects a larger building, creates complex structural alterations, involves flats, or changes how loads are transferred through the structure.
When do homeowners need to think about Building Regulations Part A?
Most structural home improvements need Building Regulations approval in some form. Planning permission and Building Regulations are separate systems, so having planning approval does not automatically mean the structure is approved.
Projects where Part A commonly applies
- rear, side, wraparound or two-storey extensions,
- loft conversions and dormer additions,
- garage conversions involving structural openings,
- removing or altering load-bearing walls,
- forming new door or window openings,
- chimney breast removals,
- roof alterations, re-roofing with heavier materials, or structural roof changes,
- basement works, underpinning or major groundworks.
Some minor works may not need a full structural design package. However, if the work affects the stability of the building, it is sensible to check before starting.
Quick costs snapshot: Part A structural safety
- Structural calculations for a simple beam: often a few hundred pounds, depending on complexity and site information.
- Extension structural package: may include foundations, steelwork, lintels, roof structure and lateral stability.
- Building Control fees: separate from the engineer’s fee and usually paid to your local authority or Registered Building Control Approver.
- Extra investigation: trial holes, drainage surveys or soil checks may add cost where ground conditions are uncertain.
These are broad guide points, not fixed prices. The right allowance depends on your house, the proposed work and what Building Control asks for.
Structural calculations and Building Control approval
For many projects, the key evidence for Building Regulations Part A is a set of structural calculations prepared by a competent structural engineer. These calculations explain how beams, foundations, rafters, joists, posts, lintels and other structural elements have been sized.
Building Control will review the information and inspect the work at key stages. Depending on the project, they may want to see:
- Building Regulations drawings,
- structural calculations,
- beam layouts and connection details,
- foundation details,
- padstone or bearing details,
- roof structure details,
- site inspection records.
Our guide to plans for Building Regulations explains how the drawings fit together with the engineer’s calculations and Building Control submission.
Not sure whether your project needs structural calculations?
We’ll review your proposed works and explain what Building Control is likely to expect before you start building.
Building Regulations Part A vs planning permission
One of the most common misunderstandings is assuming that planning approval covers structural safety. It does not. Planning permission mainly considers the principle, appearance, scale and impact of the proposal. Building Regulations look at whether the work is technically safe and compliant.
Planning permission usually asks: “Is the development acceptable?”
Planning officers consider matters such as design, overlooking, scale, materials, neighbour impact and local planning policy. Our wider planning permission guide explains that side of the process in more detail.
Building Regulations Part A asks: “Will the structure stand up safely?”
Building Control focuses on structural adequacy, fire safety, insulation, ventilation, drainage and other technical matters. Therefore, a project can have planning approval but still need structural calculations and Building Regulations approval before or during construction.
Step-by-step checklist for Building Regulations Part A
If your project involves structural work, use this simple process before the builder starts on site.
HowTo checklist: dealing with Building Regulations Part A
- Confirm the scope of work. List any walls, roofs, floors, chimneys, openings, foundations or beams affected by the project.
- Check whether Building Control approval is needed. Most structural alterations will need some form of approval or inspection.
- Prepare Building Regulations drawings. These should show the proposed construction clearly enough for review and pricing.
- Appoint a structural engineer where needed. Ask for calculations covering beams, foundations, roof alterations or other structural elements.
- Submit to Building Control. This may be through your local authority or a Registered Building Control Approver.
- Wait for comments before ordering key materials. Building Control or the engineer may request changes.
- Arrange site inspections. Foundations, steel beams, insulation and other stages may need inspection before they are covered.
- Keep records. Store drawings, calculations, inspection notes and the completion certificate safely for future sale or remortgage.
Common Building Regulations Part A mistakes
Structural mistakes are often expensive to fix because the work may be hidden inside walls, ceilings or foundations. A little preparation before construction usually saves time and stress later.
Common problems we see
- Assuming a wall is non-load-bearing because it “looks lightweight”.
- Ordering steel beams too early before calculations are finalised.
- Not checking foundation depth near trees or drains.
- Missing padstone details where steel beams bear onto walls.
- Covering up work before Building Control inspections.
- Using planning drawings for construction even though they do not contain enough structural detail.
How Part A links with other Building Regulation Parts
Part A rarely works in isolation. A safe structure also needs to coordinate with other parts of the Building Regulations.
- Part B may affect fire resistance of structural elements.
- Part C may affect ground moisture, damp-proofing and site preparation.
- Part F may affect ventilation where layouts are changed.
- Part L may affect insulation when floors, roofs and walls are upgraded.
- Part K may affect stairs, guarding and protection from falling.
- Part M may affect access where the layout or entrance is changed.
This is why coordinated drawings matter. For example, a beam might satisfy Part A structurally, but the surrounding ceiling may also need the correct fire protection under Part B.
FAQs: Building Regulations Part A
What is Building Regulations Part A?
Building Regulations Part A is the structural safety part of the Building Regulations. It covers loading, ground movement and disproportionate collapse. For homeowners, it is most relevant when building an extension, converting a loft, removing load-bearing walls, forming large openings or changing the roof structure.
Is Building Regulations Part A a law?
The Building Regulations 2010 are the legal requirements in England. Approved Document A is official guidance showing one way to satisfy the structural requirements. You can use other methods, but you must still demonstrate that the building work complies.
Who regulates building standards?
Building standards are enforced through Building Control. This may be your local authority building control team or a Registered Building Control Approver, depending on the route you choose. They review information, inspect work and issue completion documentation where the work complies.
Do I need structural calculations for Building Regulations Part A?
You often need structural calculations if the work affects beams, load-bearing walls, foundations, floors, roofs, chimneys or large openings. Building Control may request calculations to prove the proposed structure is safe.
Does planning permission cover Building Regulations Part A?
No. Planning permission and Building Regulations approval are separate. Planning considers whether the development is acceptable in planning terms, while Part A deals with whether the structure is safe and stable.
What happens if I remove a load-bearing wall without approval?
Removing a load-bearing wall without proper design and approval can create serious safety risks. It can also cause problems with Building Control records, insurance, remortgaging and selling the property. Always check before removing walls.
Does Building Regulations Part A apply to loft conversions?
Yes. Loft conversions usually involve structural work, including floor strengthening, roof alterations, beams, dormers and stair openings. Building Control will normally expect drawings and structural calculations.
Does Part A apply to extensions?
Yes. Extensions usually need suitable foundations, walls, roofs, lintels, beams and structural stability. The requirements depend on the size, storeys, ground conditions and how the extension connects to the existing house.
Can I use standard building details instead of a structural engineer?
Sometimes standard details may be enough for simple work. However, once loads, spans, ground conditions or openings become more complex, Building Control may ask for engineer’s calculations.
Need help understanding what Building Control will ask for?
Tell us what you are planning and we’ll explain the drawings, calculations and approvals you are likely to need.
Next steps & useful guides
If you are planning work that affects the structure of your home, these related PME guides will help you understand the wider approval process:
- Building Regulations: Complete Homeowner’s Guide
- Plans for Building Regulations: What Drawings You Need
- Planning Permission Guide for Homeowners
- Extension Drawings Explained
- Making Plans: Complete Guide to Costs, Drawings & Approval
- Main purpose To make sure buildings are structurally safe, stable and able to carry loads safely.
- Main sections A1 loading, A2 ground movement and A3 disproportionate collapse.
- Common homeowner triggers Extensions, loft conversions, wall removals, new openings, steel beams, roof alterations and foundation work.
- Typical evidence Building Regulations drawings, structural calculations, foundation details and Building Control inspections.
- Not the same as planning Planning approval does not prove structural safety. Building Regulations approval is separate.
- Best first step Check your proposal before building, especially if any wall, floor, roof, beam or foundation is affected.
Not sure where your project sits? Ask Plans Made Easy to check your Building Regulations requirements before work starts.
Official guidance and useful references
For the latest official guidance, check these sources:
- GOV.UK – Approved Document A: Structure
- GOV.UK – Building Regulations Approved Documents collection
- Planning Portal – Approved Document A guidance
- Legislation.gov.uk – The Building Regulations 2010
How Plans Made Easy can help
Building Regulations Part A can feel technical, but for most homeowners the practical question is straightforward: will the proposed work be structurally safe, and can Building Control approve it?
Our team can prepare clear Building Regulations drawings, coordinate with structural engineers, and help you understand what information Building Control is likely to need. That way, your builder has better information, your approval route is clearer, and you reduce the risk of costly changes once work starts.
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