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[email protected] | 020 8935 5160
Need a quick price for your project? Get a quote
Article By: Tom Ayre
Date: November 3, 2025
If a structural engineer or party wall surveyor has recommended movement monitoring for your project, or you want to understand what you’re commissioning before you sign off on it, this guide walks you through the full process. We cover every stage from initial target installation through to final removal, including what happens when a trigger level is exceeded.
Do You Need a Building Monitored For Movement?
Structural movement monitoring involves installing fixed targets or prisms on a building or structure to measure movement over time, both horizontally and vertically. This method provides accurate, ongoing data that helps detect any shifts or changes in structural stability.
The results are delivered in clear report and graph formats, making it easy to spot movement trends. If predefined movement thresholds are exceeded, this can trigger further investigation or prompt timely remedial action to prevent damage or safety risks.
Movement monitoring is essential for projects where structural stability may be affected. It is particularly valuable for developments near party walls, such as basement excavations, underpinning works, or demolitions.
Monitoring can be carried out manually, using a surveyor with a total station making periodic site visits, or automatically, using sensors that record data continuously without on-site attendance. The right method depends on the project’s risk level, budget, and how quickly you need to be alerted to any movement
Movement monitoring is used to track whether a building or structure is moving or settling during nearby construction works. It provides reassurance and evidence for homeowners, structural engineers, and party wall surveyors by identifying any unexpected changes early on.
You may require movement monitoring if:
Excavations or deep foundations are being installed close to existing structures
Basement works or underpinning are taking place nearby
You’re carrying out works under the Party Wall etc. Act 1996
A structural engineer recommends it as part of their risk assessment
There’s concern about pre-existing cracks or movement in the property
Monitoring ensures any movement is detected promptly, allowing decisions to be made early, and helping prevent costly damage or disputes later.
If your neighbour is planning a basement excavation, you can read more about what to expect in our guide.
The process below covers a standard manual monitoring survey using reflective targets and a total station, which is the most common method for residential and commercial projects.
Once a movement monitoring survey company has been appointed, the first step is to install monitoring targets at the agreed locations., prior to any construction work taking place. For a typical residential property, this may include the front and rear elevations of both your home and any adjoining neighbour’s properties.
Access is essential at this stage, as targets need to be securely fixed to walls which may be high up and / or on your neighbours’ property. This may require coordination if access to their land is necessary.
The targets are usually small reflective stickers, fixed to the wall using a durable adhesive designed to keep them in place throughout the monitoring period. Installation is typically carried out using existing access points such as windows, ladders, or scaffolding. If safe access cannot be achieved, the surveyor will note this and omit those locations from the setup.
Once the monitoring targets have been securely fixed and the adhesive has fully dried, the surveyor will carry out an initial survey to record the baseline coordinates of each point. These baseline readings serve as the reference for all future measurements and are essential for detecting any movement over time.
Using a high-precision total station, the surveyor captures the exact position of each target with an accuracy of approximately 1–2 mm. To ensure consistency across future visits, control points are also established away from the area of construction. These control points allow the instrument to be set up accurately in the same reference frame each time.
It’s important for both the surveyor and the client to consider long-term access to consistent setup locations. For example, if a basement excavation is planned in a rear garden, this could later restrict access or visibility, potentially affecting the accuracy of ongoing monitoring.
After the initial site visit, the monitoring surveyor returns to the office with the collected data, including baseline coordinates, control station positions, site photographs, and relevant notes. This information is then compiled into a detailed monitoring setup report, which is shared with the client and any relevant stakeholders for review and feedback.
The report includes essential details such as the agreed trigger levels for movement, photographs of each target location, descriptions of the monitoring equipment used, and any site-specific observations. This document forms the foundation for the ongoing monitoring programme and ensures all parties are aligned on the methodology and expectations from the outset.
Once the project begins, it’s typically the ideal time to start regular movement monitoring. The ongoing monitoring process closely mirrors the initial baseline setup. During each visit, the surveyor sets up their total station using the established control points and re-measures the coordinates of all installed targets.
Typically, the monitoring results are presented in 3 axes, the easting (X), northing (Y) and elevation (Z). With this data, the on-site surveyor can tell which direction and what extent a movement monitoring point has moved over time.
The total station then compares these new readings with the original baseline to detect any movement. Minor shifts may fall within acceptable tolerance levels, but if movement exceeds the predefined trigger thresholds, the surveyor will raise an alert. In such cases, the site owner, project manager, or structural engineer must be notified immediately, as significant movement could indicate a potential safety risk or require remedial action.
Monitoring results are usually issued within 24 hours of the site visit. The data is compiled into a clear and concise report, including tabulated readings, graphs showing movement trends, and relevant commentary. These reports are sent via email to key stakeholders such as the client, project manager, structural engineer, or party wall surveyor.
If the results reveal anything unusual, such as unexpected movement or a trigger level being exceeded, the monitoring team can discuss the findings over the phone. This ensures concerns are addressed quickly, and appropriate action can be taken without delay.
Once monitoring is no longer required, the reflective targets can be easily removed. This can be carried out by the site contractor, the property owner, or by arranging a return visit from the monitoring survey company. The targets are disposable and do not need to be kept after the project ends. In some cases, removing the adhesive may lift small areas of paint, which can be touched up as needed to restore the surface.
A trigger level is a predefined threshold of movement. If a monitoring point moves beyond this amount, it flags that something may require attention. Trigger levels are usually set by the structural engineer or party wall surveyor before works begin, and they are documented in the setup report.
Trigger levels are typically split into two stages. An amber trigger, sometimes called a warning level, indicates movement that warrants closer attention and more frequent monitoring. A red trigger indicates movement that requires work to pause immediately while the project team assesses the cause.
The actual figures depend on the structure, ground conditions, and the type of works being carried out. For a typical residential party wall project, amber triggers are often set in the range of 5 to 10mm, with red triggers at 10mm +. Older or more sensitive structures may have tighter thresholds.
It is important that trigger levels are agreed and documented before works start, not added retrospectively. If movement does exceed a trigger level, having that agreed threshold on record is important for both safety management and any future legal or insurance discussions.
For more detail on what happens when thresholds are exceeded, see our Monitoring – Structural Movement service page
Total station monitoring using reflective targets is the standard method covered in this guide, but it is not the only option. Here is a brief overview of the main methods and when each is typically used.
Total station with reflective targets: A surveyor visits site at agreed intervals and measures the position of fixed targets to within 1 to 2mm. Best for: projects where periodic readings are sufficient and cost-efficiency matters. Typical use: residential basement and party wall projects.
Automated total station (robotic monitoring): A motorised total station scans targets automatically without a surveyor on site. Readings can be taken every few minutes and alerts sent if thresholds are exceeded. Best for: high-risk projects or structures requiring near real-time data. Typical use: tunnelling, demolition near sensitive structures, infrastructure projects.
Tilt sensors and inclinometers: Electronic sensors fixed to a structure measure changes in angle over time. Can be monitored remotely and continuously. Best for: retaining walls, deep excavations, structures where horizontal rotation is the primary concern.
Vibration monitoring: Sensors measure ground-borne vibration from nearby construction activity, usually recorded against BS 7385 limits. Best for: piling, demolition and any works generating significant ground vibration near existing structures.
Crack gauges and tell-tales: Manual or electronic gauges measure the width of an existing crack over time. Best for: targeted monitoring of a specific known crack rather than whole-structure monitoring. Lower cost, suitable as a standalone method for lower-risk projects. Read more about our crack monitoring service.
If you are unsure which method is appropriate for your project, speak to your structural engineer or contact us for a recommendation.
Using a high-precision total station, readings are typically accurate to within 1 to 2mm. Digital level surveys can achieve accuracy of around 0.5mm. Automated sensors can vary but are generally comparable.
Under the Party Wall etc. Act 1996, the building owner carrying out the works is usually responsible for the cost of any monitoring required to protect the adjoining owner’s property. This will normally be confirmed in the party wall award.
Yes. If works are paused, monitoring visits can be suspended and resumed when works restart. It is good practice to take a reading just before the pause and just before works resume so any movement during the break is captured.
Structural movement monitoring measures the overall position of a building or wall in three dimensions, detecting any horizontal or vertical shift. Crack monitoring specifically tracks the width of an individual crack. Both can be used on the same project and are often specified together.
Once targets are installed and control points established, the surveyor typically works from a fixed setup location on the public highway or a neighbouring area. Access to the property is only needed if targets are installed somewhere the surveyor cannot reach independently such as a garden or internal areas.
Results are typically emailed within 24 hours of each site visit. If anything unusual is detected, the team will usually call the site contact the same day.
Do You Need a Building Monitored For Movement?
