Background

In the heart of Central London, a renowned residential developer undertook a significant basement excavation project for a luxury property. The project involved extending the basement to create additional living space, including a gym, home theatre, and wine cellar. Given the property’s value and proximity to other high-end homes, precision and care were paramount throughout the excavation process.

The developer recognised the potential risks associated with such an ambitious project, particularly in an area known for its dense urban environment and historical structures. To mitigate these risks and ensure the safety of the surrounding properties, the developer engaged Laser Surveys Ltd to provide movement monitoring services.

Objectives

The primary objectives of the basement monitoring project were:

• Structural Integrity: Monitor the structural integrity of the existing building during and after excavation to prevent any damage or subsidence.

• Neighbouring Properties: Ensure that the excavation process did not negatively impact the adjacent high-value residential properties, to the satisfaction of the appointed Party Wall surveyors.

• Compliance: Provide data to support monitoring specification, as agreed by Structural Surveyors / Party Wall Surveyors / Insurers

Challenges

The project presented several challenges:

1. Dense Urban Environment: The property, located in a tightly packed neighbourhood, requiring careful consideration of the impact on neighbouring buildings. An area where adequate monitoring control would need to be established on surrounding stable structures.

2. Historical Structures: Some of the adjacent properties were historical buildings, necessitating a sensitive approach to monitoring.

3. Complex Excavation: The excavation involved deep digging, piling and underpinning of existing foundations, which increased the risk of structural movement.

Our Approach

Laser Surveys Ltd deployed a comprehensive monitoring strategy tailored to the unique needs of the project. Our process is as follows:

1. Tolerances, trigger values and accuracy are established between us and the client to ensure realistic expectations of the project.

2. A method of installing targets and their locations is presented.

3. A programme of works is discussed along with the frequency of visits.

4. The quotation is presented and accepted, along with details of who should receive the results and be informed directly by telecom / e-mail if the trigger values are breached.

Results

The movement monitoring services provided by Laser Surveys Ltd proved to be instrumental in the success of the project. Key outcomes included:

• Structural Damage: Throughout the 12-month excavation process, the only recorded visible damage ranged from ‘0’ to ‘1’ on the BRE classification table. The monitoring allowed the construction team to adjust their methods, preventing any significant issues.

• Compliance: The monitoring data provided by Laser Surveys Ltd ensured that the project remained fully compliant with the movement tolerances, as agreed by Structural Surveyors / Party Wall Surveyors / Insurers.

• Project Efficiency: Potential issues were identified and addressed before they could escalate, keeping the project on schedule. Laser surveys have worked alongside Basement construction projects for 20 years, building a good understanding with the site teams. There are times when the conditions required for accurate readings conflict with the conditions of a working site. Through good communication, understanding and reasonableness on both sides, we always provide accurate monitoring without any disruption to the construction project.

• Client Satisfaction: The developer was highly satisfied with the precision and reliability of the monitoring services provided. The successful completion of the basement excavation without incident enhanced the reputation of both the developer and the property. Once the construction reached the stage where monies held in an ESCROW account could potentially be released, Laser Surveys flexibility allowed the next programmed visit to be brought forward and speedily issued, enabling the client to close the account.

Conclusion

The basement excavation project for this luxury London property demonstrated the importance of comprehensive monitoring in ensuring the safety and success of complex construction projects. Laser Surveys’ use of advanced monitoring technology and a tailored approach allowed the developer to carry out a challenging project with confidence.

For projects where precision and safety are paramount, Laser Surveys Ltd offers the expertise and technology to protect your investment and ensure successful outcomes.