This article covers Part A Structure, with practical UK guidance, examples and key points to consider before planning or ordering materials.
What Is Part A Structure in UK Building Regulations?
Part A Structure is the section of the UK Building Regulations that deals with the structural stability and safety of buildings in England. It is supported by Approved Document A , which gives practical guidance on loading, foundations, walls, floors, roofs, chimneys, ground movement and disproportionate collapse. In simple terms, Part A asks one essential question: will the building safely carry its own weight, the people and contents inside it, environmental actions such as wind and snow, and any accidental or abnormal forces that are reasonably expected for that type of building?
This 2026 version of the page is written for homeowners, architects, builders, property investors, surveyors and small developers who need a clear starting point before submitting drawings or working to Building Control. It does not replace a structural engineer, but it helps you understand the likely requirements before you pay for drawings, book trial pits, remove a wall, build an extension, convert a loft, add a roof terrace, or change a commercial unit.
Current Official Source
For the official statutory guidance, always check theGOV.UK Approved Document A page. The widerApproved Documents collectionexplains that Approved Documents give guidance on ways to meet the Building Regulations.
Part A applies to new buildings and to many alterations to existing buildings. It is especially important where work changes the load path of the building. The load path is the route by which weight travels from the roof, floors and walls down into the foundations and then into the ground. When a load-bearing wall is removed, when a new beam is inserted, or when a loft conversion adds habitable load to an existing roof structure, the original load path changes. That is why Building Control normally asks for structural design checks, beam sizes, padstone details, foundation notes and connection specifications.
Dead Loads
Permanent loads from the building itself, including walls, floors, roof coverings, screeds, ceilings, finishes, permanent partitions, fixed services and structural members.
Imposed Loads
Variable loads from people, furniture, storage, equipment, access use, snow and maintenance. Domestic rooms, stairs, offices and warehouses all have different design load assumptions.
Lateral Loads
Horizontal forces from wind, retaining pressure, accidental impact or frame sway. These loads can govern design on exposed sites, tall buildings and retaining structures.
Why Part A matters for homeowners and builders
Structural work is one of the highest-risk parts of any project because mistakes are often hidden behind plaster, floors, ceilings or groundworks. A poor insulation choice can usually be upgraded later. A weak foundation, undersized beam, missing restraint strap or badly supported chimney breast can create long-term movement, cracking, water ingress, resale problems and safety risks. For this reason, Part A compliance should be planned before construction begins rather than checked after work is complete.
Good Part A design also improves project speed. Building Control officers are more likely to accept a submission when the drawings clearly show foundations, bearings, wall construction, floor joists, roof structure, lateral restraint and the engineer’s working. Builders can price more accurately, homeowners can avoid surprise costs, and surveyors can understand what was approved when the property is sold.
Part A Structural Loading — 2026 Reference Guide
Structural loading is the starting point for Part A design. Every beam, wall, floor, roof and foundation must be sized for the loads it receives. For simple domestic buildings, Approved Document A gives prescriptive guidance, but modern projects often need Eurocode-based working because layouts are more open, spans are longer, roofs are heavier, and homeowners frequently add rooflights, green roofs, solar panels, large glazing, bi-fold doors and steel goalpost frames.
The values below are practical guide ranges for early-stage estimating. They are not a substitute for site-specific engineering checks. Actual design actions depend on span, use, materials, location, exposure, snow zone, roof pitch, load combinations, vibration criteria, deflection limits, fire resistance and the condition of the existing structure.
- Element / Area: Domestic habitable floor; Typical Imposed Load: 1.5 kN/m²; Design Notes: Bedrooms, living rooms and normal domestic use; Engineer Trigger: ✓ Usually simple
- Element / Area: Domestic stairs and landings; Typical Imposed Load: 2.0 kN/m²; Design Notes: Higher use due to circulation and concentrated movement; Engineer Trigger: ✓ Usually simple
- Element / Area: Flat roof — maintenance access only; Typical Imposed Load: 0.6 kN/m²+ snow check; Design Notes: Must account for dead load, snow, waterproofing and falls; Engineer Trigger: Depends
- Element / Area: Green / sedum roof; Typical Imposed Load: Project specific; Design Notes: Saturated soil, drainage boards and planting can add major dead load; Engineer Trigger: ✗ Required
- Element / Area: Roof terrace / balcony; Typical Imposed Load: Higher live load + guarding load; Design Notes: Designed as occupied space, not a maintenance roof; Engineer Trigger: ✗ Required
- Element / Area: Commercial office floor; Typical Imposed Load: 2.5 – 5.0 kN/m²; Design Notes: Partitions, storage, raised floors and occupancy vary; Engineer Trigger: ✗ Required
- Element / Area: Warehouse / storage floor; Typical Imposed Load: 5.0 – 7.5 kN/m²+; Design Notes: Forklifts, pallets, racking and point loads dominate; Engineer Trigger: ✗ Required
2026 load checks many projects forget
In 2026, many domestic projects are no longer “simple” in structural terms. Large openings for kitchen extensions often need a steel beam, a box frame or a goalpost frame to resist both vertical and lateral loads. Rooflights and lanterns can alter rafter, purlin and trimmer loads. Solar panels add relatively modest dead load, but they change wind uplift detailing and roof fixing checks. Air source heat pumps, hot-water cylinders, batteries and plant decks can create concentrated loads that should not be assumed to be covered by ordinary domestic floor values.
For SEO and user intent, the most searched structural loading questions are usually about load-bearing wall removal working , steel beam size for extension , RSJ working Building Control , domestic floor load UK , flat roof load UK , and foundation depth guide near trees . This page includes those terms naturally because they match the real problems users and Building Control teams deal with every day.
Do not size beams from internet tables alone
Beam design depends on span, bearing, load width, wall type, lateral restraint, deflection, fire protection and connection details. Use this guide as an early warning resource, then provide full working from a competent structural engineer where required.
Part A Foundation Depth Requirements — UK 2026
Foundation design under Part A must transfer building loads safely into the ground without causing excessive settlement, heave, rotation, cracking or instability. The minimum foundation depth is not simply a fixed number. It depends on soil type, nearby trees, groundwater, frost, made ground, previous excavations, drains, slopes, retaining walls and the load from the proposed building.
For a normal domestic extension, Building Control will often inspect the trench before concrete is poured. If the trench reveals soft spots, filled ground, roots, old drains, water, peat, clay shrinkage, previous foundations or unexpected services, the inspector may ask for deeper excavation, a wider strip, a reinforced foundation, a raft, piles, or an engineer’s design. That is why trial pits and early ground checks are cheaper than finding problems after the digger is on site.
Trees, Clay and Foundation Depth
Shrinkable clay near trees is one of the biggest causes of domestic foundation depth changes. For warranty or new-build work, check theNHBC Standardsand ask the designer to account for tree species, mature height, distance, soil volume-change potential and heave protection.
- Ground Condition: Rock / dense gravel; Guide Foundation Depth: 450mm+; Likely Foundation Type: Strip or pad foundation; 2026 Design Risk: ✓ Low
- Ground Condition: Firm clay without trees; Guide Foundation Depth: 750mm+; Likely Foundation Type: Mass concrete strip foundation; 2026 Design Risk: Check shrinkage
- Ground Condition: Shrinkable clay near trees; Guide Foundation Depth: 900mm – 3,000mm+; Likely Foundation Type: Deep strip, trench fill, piles or heave protection; 2026 Design Risk: ✗ High
- Ground Condition: Sand / loose gravel; Guide Foundation Depth: 500mm – 700mm+; Likely Foundation Type: Wide strip, raft or engineered solution; 2026 Design Risk: Medium
- Ground Condition: Made ground / fill; Guide Foundation Depth: To natural competent ground; Likely Foundation Type: Piles, raft or engineered foundation; 2026 Design Risk: ✗ Very high
- Ground Condition: Peat / soft organic ground; Guide Foundation Depth: To competent strata; Likely Foundation Type: Piled foundation usually required; 2026 Design Risk: ✗ Extreme
Foundation width, bearing and concrete notes
Foundation depth is only one part of the design. The foundation must also be wide enough to spread the load onto the soil without exceeding bearing capacity. A lightly loaded single-storey masonry extension on good ground may use a standard strip foundation, while a two-storey extension, chimney, pier, steel column, goalpost frame or concentrated load may need a larger pad or reinforced concrete detail. Building Control will also want continuity around corners, proper step details on sloping ground, adequate cover to reinforcement, correct concrete specification and protection from frost or contamination.
Where new foundations are close to existing buildings, care is needed to avoid undermining the existing footings. Digging too deep beside a neighbour’s house, old boundary wall or shared drain can create movement or Party Wall issues. On terraced houses and semi-detached homes, structural design should be coordinated with the Party Wall etc. Act process where applicable. The foundation detail should also avoid bridging the damp proof course and should coordinate withDPC height working, drainage falls and external ground levels.
Best practice before excavation
Ask for a site visit, trial pit, drainage search, tree survey and preliminary foundation strategy before final drawings. The cost is usually small compared with delays caused by redesigning foundations after trenches are open.
2026 Building Regulations Update — What Changed and What Still Applies to Part A?
For 2026 content accuracy, it is important to separate Part A structure from other Approved Documents. The official GOV.UK page for Approved Document A still identifies the structure document as the statutory guidance covering building loading and construction of structural elements such as foundations, walls, floors, roofs and chimneys. In 2026, the Building Safety Regulator is also reviewing Approved Documents and technical guidance across the system, so designers should always check the latest GOV.UK page before submission.
The most visible 2026 regulatory news is connected with the Future Homes and Buildings Standards and updated guidance for Part L and Part F, with implementation dates and transitional arrangements coming later. That does not remove the need to comply with Part A. In practice, structure, energy, ventilation, overheating, fire safety and moisture all interact. For example, thicker insulation, green roofs, photovoltaic panels, air-source heat pumps, plant decks and new ventilation routes can all add loads or openings that must be checked structurally.
Current as of 17 June 2026
This page uses a 2026 update date and links to current official resources so users can verify guidance before submitting to Building Control.
Higher-Risk Building Awareness
Projects involving higher-risk buildings, multi-storey residential work or complex alterations may require a different approval route and specialist competence.
Future Homes Interfaces
Low-carbon design can change structural assumptions through heavier roofs, plant loads, service routes, fixings and fabric upgrades.
Useful 2026 official links
CheckBuilding Safety Regulator strategic plan 2026 to 2027,Building Circular 01/2026, and theApproved Documents indexbefore relying on any online summary.
How to write “2026 data” correctly on a Part A page
A good 2026 SEO page should not claim that Part A has been fully rewritten unless that is confirmed by official guidance. A safer and more professional wording is: “Updated for 2026 with current Building Control practice notes, Building Safety Regulator context, Future Homes interface notes and official GOV.UK links.” This avoids misleading users while still making the page fresh, helpful and search-friendly.
The structure of this page is designed around real search intent: users want to know whether they need working, how deep their foundations should be, whether a structural engineer is needed, what loads apply, and what Building Control will ask for. These are transactional and informational searches, so the page includes a guide, tables, detailed explanatory content, FAQs and related guide links.
When Does Part A Structure Require a Structural Engineer?
Approved Document A contains prescriptive guidance for common building situations, but many modern projects fall outside simple rules. A structural engineer is normally required when the design needs working, when a member is non-standard, when load paths change, when the ground is uncertain, or when Building Control asks for proof that the proposed structure is safe. In 2026, Building Control bodies are placing more emphasis on competence, traceable working and clear design responsibility, so professional sign-off is important.
Load-Bearing Wall Removal
Removing a wall, chimney breast, pier or masonry nib normally requires beam working, bearing checks, padstones, restraint details and temporary works planning.
4+ Storeys or Complex Buildings
Taller buildings require more robust checks for stability, tying, lateral restraint, accidental actions and progressive collapse considerations.
Problematic Ground
Made ground, peat, shrinkable clay, trees, slopes, retaining structures and nearby excavations can all make foundation design engineering-led.
- Large openings:Bi-fold doors, corner openings and open-plan kitchen extensions often need steel beams, columns or goalpost frames.
- Long spans:Spans over 6m usually need working for bending, shear, deflection, vibration and bearing.
- Loft conversions:New floor joists, steel beams, dormers and roof alterations normally require working.
- Basements and retaining walls:Earth pressure, water pressure, surcharge and movement risks require an engineered design.
- Commercial and industrial work:Variable occupancy, storage loads, plant loads and public safety requirements require structural design.
- Non-standard materials:SIPs, CLT, ICF, steel frames, glass structures, modular systems and unusual roof build-ups should be checked by specialists.
- Existing building defects:Cracks, bowing walls, settlement, historic alterations, damp damage or timber decay can change safe load paths.
Use a competent structural engineer for non-standard work
For professional advice, search theInstitution of Structural Engineers Find an Engineerservice. Building Control may reject working that are incomplete, not project-specific, or not prepared by a competent person.
Part A Building Control Checklist — What to Submit in 2026
A strong Building Control submission is clear, specific and coordinated. The most common delays happen when the architectural drawings show a wall removal or extension but the structural information is missing. Use this checklist before you submit your Full Plans application, Building Notice or regularisation enquiry.
Drawings
Plans, sections and elevations showing existing structure, proposed changes, foundations, bearings, floor joists, roof structure and restraint.
Working
Beam, column, padstone, foundation, roof, floor, wall and retaining working where the project falls outside prescriptive guidance.
Site Evidence
Trial pits, photos, drainage information, tree survey, ground investigation, existing foundation depth and structural condition notes.
- Document / Detail: structural design checks; Why Building Control Needs It: Proves beams, joists, columns, bearings and foundations work safely; Typical Project Stage: Before approval or before work starts
- Document / Detail: Foundation section; Why Building Control Needs It: Shows depth, width, concrete, DPC relationship and ground level; Typical Project Stage: Design and trench inspection
- Document / Detail: Load path sketch; Why Building Control Needs It: Explains how roof and floor loads transfer to walls, beams and foundations; Typical Project Stage: Plan check
- Document / Detail: Temporary works note; Why Building Control Needs It: Helps manage wall removal, propping and sequencing risks; Typical Project Stage: Before demolition or opening
- Document / Detail: Completion evidence; Why Building Control Needs It: Provides record for Building Control, lenders, buyers and future surveyors; Typical Project Stage: At final inspection
Full Plans vs Building Notice for structural work
A Full Plans application is usually better for structural projects because drawings and working are checked before work starts. This reduces risk for extensions, loft conversions, commercial fit-outs, wall removals and basements. A Building Notice can be faster for simple domestic work, but it gives less certainty because issues may be discovered during inspection. For structural alterations, many homeowners prefer Full Plans so they have a formal plan check, especially when selling or remortgaging later.
To find your local authority, use the officialGOV.UK find your local councilservice. Private building control approvers may also be used where permitted, but higher-risk building work follows different rules.
Common Projects Covered by the Part A Structure Guide
this guide is most useful at the early design stage when you need to understand whether a project is likely to remain simple or become engineer-led. Below are common UK projects where Part A is frequently relevant.
Single-Storey Extension
Check strip foundation depth, cavity wall construction, roof load, drainage conflicts, side-return openings and steel beams above glazing.
Two-Storey Extension
Additional wall and floor loads often require deeper foundations, stronger masonry, beam design and careful connection to the existing structure.
Loft Conversion
New floors, dormers and roof alterations usually need steel or engineered timber beams, restraint details and fire coordination with Part B.
Wall Removal
Load-bearing wall removal requires working, a beam schedule, padstones, bearings, temporary works and often a Party Wall review.
Commercial Fit-Out
Change of use, heavy storage, mezzanines, plant, suspended services and opening formation can all affect structural load assumptions.
Green Roof / Roof Terrace
Heavier saturated build-ups, occupancy loads and guarding forces mean roof structures usually need project-specific working.
Part A structural design checks Cost, Timeline and Approval Process in 2026
Many users searching for a Part A structure guide also want to know what happens after the first estimate. The usual process is simple: confirm the project scope, identify whether any structure is affected, gather site information, prepare drawings, ask a structural engineer for working where needed, submit the information to Building Control, complete inspections during work, and keep the final approval documents. The cost and timeline depend on how much uncertainty exists. A straight beam over a small opening is usually quicker than a basement, multi-span steel frame, piled foundation or commercial mezzanine.
For a typical domestic wall removal, the structural package may include a site review, load assessment, steel beam working, padstone detail, bearing notes and a sketch showing where the beam sits. For a single-storey rear extension, the package may include foundation notes, lintel or steel beam working, roof structure checks and wall restraint details. For a two-storey extension, the engineer may also check the existing wall, differential settlement, new floor loads, roof loads and how the new structure ties into the existing house.
In 2026, homeowners should also plan for coordination time. The architect or designer must show the engineer’s structural members correctly on the drawings. The builder must price the actual specification, not a guessed beam size. Building Control must be able to match the working with the plans. If the project is close to a boundary, the Party Wall process may also need to run before structural work starts. Good coordination reduces expensive surprises such as beams that do not fit, padstones that clash with services, or foundation details that cannot be built because of a drain.
- Project Type: Small wall opening; Typical Structural measurement: Beam and padstone working; Common Delay Risk: Unknown wall load or hidden chimney support; Best Next Step: Survey first
- Project Type: Open-plan extension; Typical Structural measurement: Steel beam, goalpost frame or column design; Common Delay Risk: Large glazing, poor bearings or lateral stability; Best Next Step: Engineer early
- Project Type: Loft conversion; Typical Structural measurement: Floor joists, steel beams, dormer and roof checks; Common Delay Risk: Existing roof not suitable for new habitable load; Best Next Step: Measure structure
- Project Type: Tree/clay foundation; Typical Structural measurement: Foundation depth, heave protection or piles; Common Delay Risk: Tree species, roots and soil plasticity unknown; Best Next Step: Ground checks
- Project Type: Commercial fit-out; Typical Structural measurement: Floor loading, plant, openings and mezzanine checks; Common Delay Risk: Change of use or heavy storage not allowed by existing design; Best Next Step: Full assessment
What makes a Part A page rank better in 2026?
A strong SEO page for this topic should answer both the working method query and the deeper compliance questions. The main keyword is Part A Structure Guide , but the supporting semantic keywords are just as important: Approved Document A guide , UK building regulations structure , structural design checks for extension , load-bearing wall removal Building Control , foundation depth guide UK , foundation depth near trees , domestic floor load UK , RSJ working Building Control , structural engineer for extension and Building Regulations Part A 2026 . These phrases are included naturally in headings, tables, FAQ answers and body copy rather than stuffed into one paragraph.
Internal links also help search engines understand topic clusters. Link this guide to yourPart B Fire Safety Guide,Part L U-Value Guide,DPC Height Guide, loft conversion guide, extension cost guide, load-bearing wall removal guide and foundation depth near trees guide. External links should point to authoritative sources such as GOV.UK, Planning Portal, NHBC and IStructE rather than random blogs.
The page should also include trust signals. Add a visible “last updated” date, explain that the method is guidance only, tell users when to call an engineer, and avoid pretending that a guide can approve structural work. This is especially important for YMYL-style construction safety content because inaccurate structural advice can cause financial loss and physical danger.
Part A Structure Always Requires Building Control Awareness
this guide gives general 2026-ready guidance only. All structural work must be checked through the correct Building Control process, and complex work should be designed by a competent structural engineer. See the FAQ section below for common approval questions.
Part A Structure — Frequently Asked Questions 2026
SEO-optimized answers to common questions about Approved Document A, structural design checks, foundations, load-bearing walls, engineers and Building Control.
Approved Document A is the official guidance that helps people comply with the structural part of the Building Regulations in England. It covers how buildings should resist loads, avoid unsafe movement and remain stable. It is about foundations, walls, floors, roofs, chimneys, loading, ground movement and disproportionate collapse.
The GOV.UK Approved Document A page remains the source to check for the current statutory guidance. In 2026, wider Building Regulations updates and Building Safety Regulator reviews are active, but you should not assume Part A has changed unless the official page confirms it. This guide is updated for 2026 with current links, Building Control practice notes and modern design issues.
A very simple single-storey extension on good ground may follow standard guidance, but working are commonly needed where there is a steel beam, large opening, flat roof, roof lantern, unusual wall, poor ground, tree risk, retaining wall or load-bearing wall removal. Building Control decides what evidence is acceptable.
Typical starting depths are around 450mm on competent rock or dense gravel, 750mm on firm clay, and 900mm or deeper on shrinkable clay. Near trees on shrinkable clay, depths can increase substantially and may need heave protection or piles. Final depth must be agreed with Building Control and should reflect the actual ground found on site.
Yes. Removing or altering a load-bearing wall is structural work and normally needs Building Regulations approval. You will usually need a structural engineer’s beam working, padstone details, bearing details, temporary support plan and inspection by Building Control before the work is closed up.
Do not rely on a generic RSJ chart for final construction. Beam size depends on span, loading width, masonry type, bearing length, padstones, lateral restraint, deflection limits, fire protection and connection details. Building Control often requires project-specific working.
A common early-stage value for domestic habitable rooms is 1.5 kN/m² imposed load. Stairs and landings are commonly higher. However, actual design should follow the relevant standards and project-specific conditions, especially for loft conversions, storage areas, roof terraces and commercial uses.
Not always, but trees near shrinkable clay are a major warning sign. The depth depends on soil volume-change potential, tree species, mature height, distance, whether trees are removed, and heave risk. Building Control or warranty providers may ask for NHBC-style foundation depth assessment.
You may need revised working, clearer drawings, extra site evidence or a different structural detail. Common reasons include missing load paths, unclear bearings, no padstone design, no foundation justification, inadequate notes for existing structure or working not matching the drawings.
Yes. Loft conversions usually change structural loading because the roof space becomes habitable floor area. New joists, beams, dormer cheeks, rafters, trimmers and supports must be designed to carry the new loads safely. Part B fire safety, Part L energy and Part K stair safety also apply.
A Building Notice may be accepted for some domestic work, but Full Plans are often safer for structural projects because working and drawings can be checked before work begins. This reduces delays when walls are opened, beams are ordered or foundations are excavated.
the working method can flag likely requirements, but commercial buildings need full structural design. Offices, shops, warehouses, mezzanines, plant rooms and public buildings have different loads, fire requirements, occupancy risks and approval needs. Engage a structural engineer early.
Keep approved drawings, working, inspection notes, beam delivery information, engineer letters, photographs before closing up, Building Control completion certificate and any warranties. These records help with resale, insurance, future alterations and surveyor queries.
Related UK Building Regulations Guides
Explore more guides and guides for structural safety, fire safety, damp proofing and energy compliance.
For related building and design resources, you can also visit ArchitectsEmporium.com.