Wave Dynamics GuidesCrack Monitoring Explained
How crack monitoring works on construction projects: pre-condition surveys, tell-tales and digital crack meters, damage categories and reporting.
In Short
Crack monitoring tracks whether existing cracks in a building are opening, closing or moving during nearby works. It uses manual tell-tales or digital crack meters fixed across the crack, with readings recorded over time and compared with alert levels.
- Starts with a pre-condition survey recording existing cracks.
- Manual tell-tales are simple; digital meters give continuous, remote data.
- Readings are compared with movement before works started.
- Often combined with vibration and ground movement monitoring.
Why Monitor Cracks?
Most buildings already have cracks from shrinkage, thermal movement or settlement. When excavation, piling or demolition starts next door, owners naturally worry that new damage is being caused. Monitoring creates an objective record, protecting both the neighbour and the contractor.
Methods
- Tell-tales: two overlapping plates fixed either side of a crack, read by eye against a grid to around 0.5 mm.
- Digital crack meters: displacement sensors that log movement continuously and send alerts.
- Demec studs and calipers: precise manual readings between fixed points.
Assessing Movement
Readings are compared with the baseline taken before works began and with seasonal changes, since cracks open and close with temperature and moisture. Damage is often described using the BRE classification, from negligible hairline cracks to severe structural damage, which helps everyone understand the significance of any change.
Reporting
Regular reports show the trend for each monitored crack, any alert exceedances and the actions taken. Where a third-party agreement is in place, reports are shared with the neighbouring owner or their engineer.
Frequently Asked Questions
How long does crack monitoring continue?
Usually from before the works start until the activities likely to cause movement are complete, and sometimes for a period afterwards to confirm the building has settled.
Can crack monitoring prove the works caused damage?
It shows when and how much a crack moved. Combined with vibration and ground movement data, it gives strong evidence either way.
This guide gives general information and is not a substitute for project-specific advice. Requirements change, so always check the current regulations, guidance and your planning conditions. Ask our team about your project.
Jon Maguire (BSc Hons MIOA) brings over 8 years of expertise in acoustic consultancy, specialising in environmental acoustics with a focus on 3D modelling, assessments, and detailed design for industrial, commercial, and energy projects. He has lead noise assessments for key clients while thriving in multidisciplinary environments. Jon’s diplomatic communication skills are ideal for stakeholder consultation.
Jack is a Field Engineer at Wave Dynamics, supporting the delivery of environmental monitoring and acoustic consultancy services through detailed on-site fieldwork. He has hands-on experience in noise monitoring, vibration monitoring, and dust monitoring across a variety of infrastructure, construction, and environmental projects. Jack is involved in the setup, operation, and maintenance of monitoring equipment, ensuring accurate data collection in line with relevant standards and project requirements. He works closely with consultants and project teams, providing reliable field support that underpins high-quality assessments and reporting.
Aidan is the Director for all U.K Operations and has worked in multiple industries including for clients in the UK and internationally operating in the residential, industry, healthcare, education, and construction sectors.
