020 7864 7245Request a fixed quote

City of London, London

Structural engineering in the City of London

Structural engineering in the City of London is mostly the art of keeping what stands: auditing an existing frame, working out how much of it can be reused, and designing the new steel and openings around it. We provide that with your drawings under a fixed quote after a free constraints check. The Square Mile has almost no houses, so our work is flats, Barbican homes, live-work conversions and small retrofits.

Fixed quote after a free constraints check

  • MCIAT chartered
  • £2m PI insured
  • LABC Partnered
  • Fixed fees, VAT included

Request a fixed quote

We use it to check conservation areas and constraints.
Pick the council that decides your application.
A few lines: what you want to build, and anything the council has already said.
Add photos or drawings

Drop files here or choose from your device

PDF, JPG, PNG, DWG · up to 10 files, 90 MB in total

    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on structural engineering

    Four steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    4. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

    Request a fixed quote
    Brick house being extended, with a wide new opening supported over the ground floor

    How the City's retrofit guidance changes the engineer's first task

    The City of London's sustainability guidance asks applicants to undertake a structural audit, including relevant testing, early on, to understand the condition and capacity of the existing structure and to use it for alterations and extensions. In the council's own summary: structural audit early; retrofit = 50% superstructure by mass retained. That last figure is its definition of retrofit, so a scheme that keeps less than half the superstructure by mass is, in the City's terms, not a retrofit.

    The guidance also covers deconstruction. A pre-deconstruction audit, listing what can be reused, should be backed by demolition drawings from the designers and by deconstruction drawings from structural engineers; where that is impractical at application stage, a condition can require it. The council's wording is deconstruction drawings from structural engineers. We prepare the audit and the drawings together, so the engineer's findings are in the application on day one and not in a condition letter later.

    House extension under construction with scaffolding, new glazed doors and building materials

    Local figures for City of London

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Retrofit guidance: undertake a structural audit (including relevant testing) early to understand the condition and capacity of the existing structure, and optimise existing structural capacity for alterations and extensions. The City defines retrofit as retaining and reusing at least 50% of the existing superstructure by mass.structural audit early; retrofit = 50% superstructure by mass retained—cityoflondon.gov.uk, City of London Planning for Sustainability SPD (February 2025), Chapter 3 Retrofit and Reuse, PDF p.18 ('Undertake a structural audit'); definition PDF p.16
    Pre-deconstruction audit (reuse schedule) should be supported by salvage/demolition drawings from the architects and deconstruction drawings from structural engineers; where not practical at application stage, the information can be triggered by conditions.deconstruction drawings from structural engineers—cityoflondon.gov.uk, City of London Planning for Sustainability SPD (February 2025), Chapter 3 Retrofit and Reuse, PDF p.15
    Listed building entries637 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Scheduled monuments53 scheduled monuments intersecting the LPA boundary (Historic England)—planning.data.gov.uk
    Conservation areas28 named conservation areas published by the council—planning.data.gov.uk
    Households living in a house2 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Minor application decisions173 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Minor applications granted97.1 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Borough CIL residential rate£251.05/m² (Riverside); £159.00/m² (Rest of City) [schedule rates £150 and £95]Indexed rate for planning permissions granted in 2026 (Annual CIL Rate Summary 2026, effective 1 January to 31 December 2026)cityoflondon.gov.uk
    AD A para 5.1(d) and para 5.3 (key elements; Diagram 24)Class 2b: on notional removal of one supporting column, or one nominal length of load-bearing wall, in each storey, the area of floor at risk of collapse must not exceed 15% of that storey's floor area or 100 m2, whichever is smaller; otherwise design the element as a 'key element' for an accidental load of 34 kN/m2—gov.uk

    A blank value means the figure has not been published, not that there are none. Check your own address with the council.

    Councils bordering City of London
    Building regulations, layer by layerPart A: structure: Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments. Part B: fire safety: All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604. Part L: insulation: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. Part K: stairs: 2.0 m clear headroom over stairs. Full plans application: Building control body must decide a full plans application within 5 weeks, or longer if agreed in writingPart A: structurePart B: fire safetyPart L: insulationPart K: stairsFull plans applicationABCDE

    Building regulations, layer by layer

    The Approved Documents that shape most house projects, from structure to the application itself.

    A · Part A: structure
    Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments
    B · Part B: fire safety
    All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604
    C · Part L: insulation
    New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4
    D · Part K: stairs
    2.0 m clear headroom over stairs
    E · Full plans application
    Building control body must decide a full plans application within 5 weeks, or longer if agreed in writing

    What an audit looks like on a City flat or Barbican home

    A structural audit of a typical City residential unit starts with the records, then moves to opening-up. We trace the frame, find where slabs span and how they are supported, test materials where it matters, and mark which walls carry load. The result is a short report that says what can be cut, what must be propped and what the new beam or lintel sizes would be.

    For listed buildings the Barbican guidance applies, in the council's Barbican Estate Listed Building Management Guidelines: Volume I Introduction and Volume II Residential (SPD). The estate is listed, so openings and plant often need to be argued from the audit rather than assumed. The borough holds 637 listed building entries, with 86 at Grade I, which is why the heritage statement and the structural report usually go in together.

    The City in numbers: small, dense and heavily protected

    Only 2 per cent of households live in a house, and the resident population is 15,631. The area carries 28 conservation areas and 53 scheduled monuments, along with 1 Article 4 direction and 5 Heritage at Risk entries. Underground archaeology is as much a design constraint as the visible heritage.

    The council's decision record is unusually strong for small schemes. In its latest twelve months of published figures it granted 97.1 per cent of 173 minor applications and decided 93.1 per cent in time or within an agreed extension. That is a record of the past and says nothing certain about your application. Flat values averaged £709,939, so structural changes are priced against compact, expensive floor area.

    Disproportionate collapse and party walls in tall buildings

    In a tall block the engineer checks more than the new opening. The national guidance on disproportionate collapse sets a limit for key elements: Class 2b: on notional removal of one supporting column, or one nominal length of load-bearing wall, in each storey, the area of floor at risk of collapse must not exceed 15% of that storey's floor area or 100 m2, whichever is smaller; otherwise design the element as a 'key element' for an accidental load of 34 kN/m2. Removing a wall in a flat can therefore mean checking the stability of the floors above, and that check goes in the calculation package. Our structural calculations in the City of London page covers it on its own.

    Work to a shared floor or wall also engages the Party Wall etc. Act 1996, and the awards that follow can take time: if a neighbour does not appoint a surveyor within 10 days of a request, the building owner can appoint one on their behalf. Our party wall notices service handles the paperwork, using the engineer's drawings as the attachment.

    How we work on a City of London structure

    We start with a free constraints check on the address, covering listing, archaeology, conservation area and the building's management rules. An engineer then reviews the records, inspects the unit and agrees the structural strategy with the design. Calculations, drawings and a specification follow, with a second chartered technologist checking the whole set before submission.

    Once the scope is agreed the quote is fixed. For the wider picture in the City, see architectural drawings in the City of London, and for a different heritage setting read our structural engineering in Croydon page. The council's levy for residential floorspace, £251.05/m² (Riverside); £159.00/m² (Rest of City) [schedule rates £150 and £95], is separate from our fee.

    What you receive

    Structural calculation sheet for a steel beam
    Sample drawing. Structural calculation for a steel beam, coordinated with the engineer.
    Pencil resting on a dimensioned technical drawing beside a scale rule
    Load take-down
    Brush across the bars.

    Other services in City of London

    Structural engineering nearby

    Questions

    What does the City of London expect from a structural audit?

    Its retrofit guidance asks for an early audit including relevant testing, summarised as structural audit early; retrofit = 50% superstructure by mass retained.

    Does the City want deconstruction drawings?

    Its guidance says a reuse schedule should be supported by deconstruction drawings from structural engineers: deconstruction drawings from structural engineers. A condition can require them later.

    How strong is the City's decision record on minor schemes?

    It granted 97.1 per cent of 173 minor decisions in its latest twelve months of published figures. That describes the past, not your application.

    Can I use a structural engineer for a Barbican flat?

    Yes, and you should: the council publishes the Barbican Estate Listed Building Management Guidelines: Volume I Introduction and Volume II Residential (SPD), and the estate is listed, so changes need evidence.

    Sources and dates

    City of London skyline glowing at dusk across the Thames under a dramatic orange sky

    Tell us about your property.

    We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.

    Request a fixed quoteCall 020 7864 7245WhatsApp