Structural movement monitoring for basements, demolition and party wall works

What movement monitoring is

A movement monitoring survey measures how a building, retaining wall or earthwork moves over time. Targets, prisms or sensors are fixed at agreed positions and resurveyed at set intervals with high-precision total stations, digital levels or automated sensors. Each round is compared with the baseline, giving vertical, horizontal and 3D movement to within a millimetre.

If movement crosses a trigger, the project team hears about it straight away so works can be paused, reviewed or remediated. The result is a documented record of how the structure behaved, which protects the engineer’s design assumptions, supports party wall awards, satisfies insurers and gives the contractor evidence if a third party makes a claim.

Where it is used

• Basement excavation and underpinning. Most of our London work. We monitor through dig-down, underpinning, raft pour and waterproofing, then reduce frequency through fit-out.
• Demolition. The structure coming down and any retained or adjoining buildings, often alongside vibration monitoring.
• Piling and ground improvement. Prism monitoring of structures combined with vibration monitoring at neighbour boundaries.
• Tunnels and infrastructure. Works near TfL, Thames Water and Network Rail assets, where third-party agreements set explicit triggers.
• Insurance and subsidence. Long-period monitoring to show whether a structure is still moving.
• Heritage and listed buildings. Tight thresholds and reporting that conservation officers scrutinise.

Methods

• Optical monitoring. 1-second total stations reading reflective targets or mini-prisms from a stable off-site control network. Typically ±1mm in 3D.
• Precise levelling. digital levels reading invar staves or wall-mounted points to ±0.5mm, where settlement is the main concern.
• Automated total stations. A robotic instrument in a fixed enclosure reading a prism network on a schedule, often hourly, with a cloud dashboard and alerts.
• Tilt monitoring. Wireless inclinometers reading every 15 minutes or so, where rotation is the failure mode.
• Vibration monitoring. Tri-axial geophones recording peak particle velocity to BS 7385 and BS 5228, with 24-hour alerts.
• Crack monitoring. Demec studs read with a digital gauge for sub-millimetre movement, plus tell-tales for a visual check.

We cover all 32 London boroughs, with most basement work in Westminster, Kensington and Chelsea, Camden, Hammersmith and Fulham, Wandsworth and Richmond, and regular schemes across Essex, Kent, Surrey, Hertfordshire and Berkshire.