Structural calculations are needed in London whenever building work changes how a house carries its weight, because Part A of Schedule 1 to the Building Regulations 2010 sets three structural requirements and building control wants evidence that a new beam meets them. Fixed Fee Plans publishes calculations from £495, prepared by a qualified structural engineer.
Key Takeaways
- Part A of Schedule 1 contains three requirements: A1 loading, A2 ground movement and A3 disproportionate collapse (legislation.gov.uk, Building Regulations 2010 Schedule 1).
- Taking out a load-bearing wall, opening up the back of a house, converting a loft or building a dormer all put new loads on members that have to be sized.
- Our calculations cost from £495. There is no separate council fee, because building control checks them within your building regulations approval.
- Steel built into a shared wall can trigger a Party Wall etc. Act 1996 notice, served at least two months before work starts. That is a separate legal process and not our service.
What does Building Regulations Part A actually require?
Part A of Schedule 1 to the Building Regulations 2010 contains three requirements. A1 says the building must carry its combined dead, imposed and wind loads to the ground safely. A2 covers ground movement from swelling, shrinkage, freezing, land-slip or subsidence. A3 says a building must not collapse disproportionately to the cause of an accident (Schedule 1).
Regulation 4 then requires building work to comply with the applicable requirements of Schedule 1 (regulation 4). That is the legal hook for every request a building control officer makes about a beam.
The practical guidance sits in Approved Document A: structure, published on GOV.UK on 1 September 2013. It does not give a ready-made answer for every opening. Its Section 2 sets sizes for traditional low-rise housing, and for solid timber floor and roof members it points to the TRADA span tables. Steel and other engineered members are designed to the standards its Section 1 lists, including BS EN 1993-1-1 for steel structures (Approved Document A, PDF).
| Requirement | What it asks | Where it shows in a calculation pack |
|---|---|---|
| A1 Loading | Dead, imposed and wind loads carried safely to the ground | Load take-down, beam and lintel sizes |
| A2 Ground movement | Subsoil movement must not impair stability | Bearing pressure at padstones and footings |
| A3 Disproportionate collapse | No collapse out of proportion to an accident | Rarely the deciding point for a house |
Which building works need structural calculations in London?
Four kinds of work account for almost every request: removing a load-bearing wall, forming a wide opening at the back of the house, converting a loft, and adding a dormer. Each moves load onto a new member, and building control asks to see that member sized on paper before it goes in.
- Removing a load-bearing wall. A steel beam takes over the wall's job, resting on padstones that spread the load into the masonry below. This is the classic open-plan knock-through.
- Rear extension openings. Joining a new kitchen to the old back wall needs a beam, and wide glazed doors need a lintel or beam over them. See how this fits a full project on our house extensions page.
- Loft floor joists and steel beams. Ceiling joists were never designed as a floor. New joists are sized, and steel usually carries the new loads. The loft conversion page covers the whole job, and the Part B fire safety guide covers the escape stair that goes with it.
- Dormers. Cutting through rafters needs trimmers, and the beams that carry them are calculated.
Calculations answer a Part A question. Whether the scheme also needs planning permission is a separate one, so run the permitted development checker first. It will tell you plainly if you need no application, even though a planning application is one of our own services.
What does a structural calculation pack contain?
A pack for a London house contains the load take-down, the beam or lintel size and grade, the padstone size and bearing, and any sized floor or roof timbers. It is laid out so a building control officer can follow each number from the loads above to the support below.
- Load take-down. Roof, floor and wall loads traced down to the opening, split into dead and imposed load as A1 describes.
- Beam or lintel sizing. The section and steel grade that carry those loads without excessive deflection.
- Padstone sizing. The bearing area needed so the masonry beneath is not overloaded.
- Floor and roof timbers. Joist and rafter sizes where the project changes them.
The calculations say what size; drawings show where it goes. Our building regulations drawings are £795 and show the beam on plan and section, so the two documents agree before they reach building control. A measured survey, £150, gives the real spans and wall thicknesses to calculate from rather than assumptions.
How does building control check structural calculations?
Building control checks calculations as part of a full plans application. An officer compares the stated loads, sizes and bearings with the drawings, queries anything that disagrees, and later inspects the steel while it is still visible. GOV.UK confirms you can choose your local authority's building control department or a private registered building control approver (GOV.UK, building regulations approval).
A beam on the drawing that is not the beam in the calculation is the kind of mismatch that draws a query. Settling it on paper costs an email; settling it after the plaster is up costs a lot more. That is why a full plans route suits structural work, and our building regulations drawings page explains full plans against a building notice.
Approved Document A also scales its expectations to the building. Table 11 puts houses not exceeding four storeys in consequence class 1, and flats not exceeding four storeys in class 2a. For class 2a, one route to compliance is to check that removing any one length of load-bearing wall leaves the area at risk of collapse within 15% of that storey's floor area or 100m², whichever is smaller (Approved Document A, paragraph 5.1 and Table 11). That is why a wall removal in a flat is a calculation job as much as a house is.
Does steel in a party wall need a party wall notice?
Often, yes. Cutting into a party structure for any purpose is a right the Party Wall etc. Act 1996 gives a building owner under section 2(2)(f), and the Act sets the process for doing it (legislation.gov.uk, section 2). It is separate from planning permission and building regulations approval (GOV.UK, party walls and building work).
The notice periods are short but fixed:
| Situation | Notice | Source |
|---|---|---|
| Work to a party structure | At least two months before work begins | Section 3 |
| Building on the line of junction | At least one month before work starts | Section 1 |
| Excavation within 3m, or within 6m on a 45-degree line | At least one month before excavating | Section 6 |
| Neighbour does not consent in writing | Dissent is deemed after fourteen days | Section 5 |
Party wall services are not ours and have no price on this site. What we can do is give the party wall surveyor an accurate beam size, because a notice that describes the steel precisely is easier to agree. Budget the two months into your programme before a builder is booked.
How much do structural calculations cost in London?
Structural calculations cost from £495 with Fixed Fee Plans, published on the structural calculations page and confirmed in writing before work starts. The figure is a floor because one beam and a loft with several steels are different amounts of calculation. No council fee applies. Building control's own charge and any party wall costs are paid separately.
For a house extension that needs planning permission, the drawing fee is £895 and the council's householder fee is £548, so the structure is one line in a longer list. The planning drawings cost guide puts every line side by side, and the fee calculator totals ours with the council's. The new building also has to meet energy rules, which the Part L guide covers. The prices page shows every fee, and the permitted development guide explains when no application is needed at all.
Frequently asked questions
Do I need calculations to remove a load-bearing wall? Yes. Building control needs to see the replacement member sized, because Part A requires loads to be carried to the ground safely. The calculation is how that is shown before the wall comes out.
Who prepares the calculations? A qualified structural engineer prepares them. We draw the building regulations set to match the pack so building control receives one coordinated submission.
Can the calculations be done after the builder has started? Building control checks them within a full plans application, so the sensible order is calculations first, then application, then the wall. Starting first means any query is settled on site instead of on paper.
Does a beam in a loft conversion need calculations as well as the floor? Yes, where steel carries new loads. The floor joists are sized against the loads in A1 and so are the beams under them, and both belong in the same pack.
Sources
All sources fetched and checked on 10 October 2026.
- The Building Regulations 2010, Schedule 1, Part A (A1 loading, A2 ground movement, A3 disproportionate collapse): https://www.legislation.gov.uk/uksi/2010/2214/schedule/1
- The Building Regulations 2010, regulation 4 (requirements relating to building work): https://www.legislation.gov.uk/uksi/2010/2214/regulation/4
- GOV.UK, Structure: Approved Document A (published 1 September 2013): https://www.gov.uk/government/publications/structure-approved-document-a
- Approved Document A: structure, 2013 edition, PDF (Section 1 standards, Section 2 sizes, Table 11 consequence classes, paragraph 5.1): https://assets.publishing.service.gov.uk/media/5a80437640f0b623026927b2/BR_PDF_AD_A_2013.pdf
- GOV.UK, Building regulations approval (local authority or private registered building control approver): https://www.gov.uk/building-regulations-approval
- Party Wall etc. Act 1996, section 1 (one month, line of junction): https://www.legislation.gov.uk/ukpga/1996/40/section/1
- Party Wall etc. Act 1996, section 2 (rights of building owner, including 2(2)(f) cutting into a party structure): https://www.legislation.gov.uk/ukpga/1996/40/section/2
- Party Wall etc. Act 1996, section 3 (two months, party structure notices): https://www.legislation.gov.uk/ukpga/1996/40/section/3
- Party Wall etc. Act 1996, section 5 (fourteen days, deemed dissent): https://www.legislation.gov.uk/ukpga/1996/40/section/5
- Party Wall etc. Act 1996, section 6 (adjacent excavation, 3m and 6m, one month): https://www.legislation.gov.uk/ukpga/1996/40/section/6
- GOV.UK, Party walls and building work (separate from planning and building regulations): https://www.gov.uk/party-walls-building-works
- Fixed Fee Plans published price list: https://fixedfeeplans.co.uk/pricing/