Structural engineer in the City of London

Structural engineering in City of London

The City of London is the Square Mile, governed by the City of London Corporation, and most of its buildings are large offices, banks and institutions. Our work here is limited to homes, flats, conversions and mixed-use buildings up to 15 m high and five storeys, which in the City means the smaller older buildings, upper-floor flats and residential pockets that sit between the major commercial blocks.

We have completed 4 projects in the City since 2019: two in EC3N around Aldgate and Tower Hill, one in EC3V near Cornhill and Lombard Street, and one in EC4M near St Paul's and Ludgate Hill. All involved alterations within existing buildings rather than new construction, which is typical of residential and mixed-use work in the Square Mile, where space is tight and every building has neighbours on several sides.

Flats in older buildings, courts and mixed-use premises

Residential stock in the City is mostly flats. Some are in purpose-built post-war estates, others in Victorian and early twentieth-century warehouses, chambers and office buildings converted to homes, often with shops, restaurants or offices on the lower floors. Narrow lanes and courts off the main streets keep a number of small older buildings that suit residential or mixed use.

These buildings often have mixed structure: load-bearing brick walls with cast iron or steel columns, filler-joist or early concrete floors, and alterations from many periods. Before forming an opening or changing how a floor is used, you need to know which elements carry load. Our structural capacity appraisal answers that for a change of use or new loads.

Made ground, archaeology, gravels and clay

The City has been built on for nearly two thousand years, so the top few metres are usually made ground and archaeological deposits, sometimes deep. Beneath that are Thames terrace gravels over London Clay. Buried watercourses such as the Walbrook and the Fleet once ran through the area, and ground along them can be softer and wetter.

For most of our City work the ground is not the main concern, because we work within existing buildings. Where alterations reach below ground, such as lowering a basement floor or adding a lift pit, the Corporation is likely to require archaeological consideration, and nearby tunnels, vaults and old foundations call for careful investigation first.

Typical structural work in the City

Our City projects centre on adapting existing buildings: opening up walls in flats, checking floors for new loads, converting upper floors of mixed-use buildings into homes, and assessing defects in older fabric. Access and working hours are tightly controlled, so designs must be buildable in small pieces.

• Wall removals and new openings in flats
• Office or upper-floor to residential conversions
• Floor loading checks for change of use
• Roof terraces on flat roofs
• Surveys of older mixed-use buildings
• Temporary propping for internal alterations

The City of London Corporation, listed buildings and neighbours

The City of London Corporation is the planning authority and runs its own Building Control service. Much of the City lies within conservation areas and it has many listed buildings, where internal structural changes may also need listed building consent. Most flats are leasehold, so the freeholder's licence is normally needed too.

Buildings in the City are packed tightly together, so party wall notices are common even for internal works near a shared wall. Our party wall guide covers the notice periods, and where a flat roof is to become usable space, our roof terrace guide explains the structural checks involved.