Temporary Works Design

Constrained Basement Temporary Works Design

At IDH, we excel in tackling complex redevelopment challenges, as demonstrated by our recent project in London.

Project Overview

A significant redevelopment project was carried out on a terraced property in London, involving extensive internal structural alterations and the construction of a new 5-metre-deep multi-level basement beneath an existing mid-terrace property. The scope included demolishing the existing upper ground floor structure, removing the rear elevation to three levels. Given the complexities of the site, our temporary works designs were critical in ensuring structural integrity throughout the construction process in this densely populated central London location.

Challenges:

  1. Limited Space and Proximity to Neighbours: Situated in central London, the site had minimal space for construction activities. The mid-terrace location required meticulous planning and coordination to mitigate any adverse effects on adjoining properties and ensure compliance with party wall agreements, whilst allowing appropriate equipment to safely access and operate within the site.
  2. Complex Structural Modifications: The proposed permanent works involved the demolition of most of the rear elevation, with multiple stacked steel box frames anchored into newly constructed underpins for support. These complexities required careful sequencing of construction activities to ensure stability and safety throughout the process, as well as to maintain lateral stability during each phase. This involved detailed analysis and simulations to predict performance under various loading conditions.
  3. Temporary Load Transfer Conditions: The precise detailing of the permanent works rendered traditional methodologies for two-stage underpinning unfeasible. This meant that during the first stage drive, the entire load from the rear elevation would bear onto a single pin. During the second stage, this load needed to transfer into the adjacent pins solely by shear dowels while the first stage pin was undermined. Traditional methods were inadequate to address these unique challenges, necessitating innovative solutions.

Solution:

To overcome these challenges, we developed a tailored, multi-faceted approach:

  1. Two-Stage Underpinning with Load Transfer: Recognising the client’s preference for two-stage underpinning to enhance safety and manageability, we engineered a sophisticated method for effectively transferring loads between underpins.
  2. Sequential Underpinning and Needling Scheme:
  • Installed the required temporary works for the first stage of underpins for the entire building to provide initial support, ensuring stability while enabling subsequent demolition.
  • Deepened select adjacent underpins to full depth ahead of the underpin directly supporting the steel beam.
  • Installed a temporary needling system to safely transfer the load from the permanent steel beam into the fully deepened adjacent underpins, thereby reducing the risk of structural failure during construction.
  • This strategy minimised additional loads on the under-construction underpin, allowing safe excavation and completion of the second stage underpinning without compromising structural integrity.

   3.   Elimination of Unviable Options: We explored an alternative masonry load distribution solution but found it inadequate through advanced analytical assessments. This analytical approach reaffirmed the necessity of our chosen method, ensuring safety and compliance.

 

Outcome:

By implementing this tailored solution, we successfully:

 

  • Achieved the Client’s Objectives: We worked with our client to understand their preferred approach and clearly presented the advantages and disadvantages of each method, to ensure the client had all the information to make an informed decision on the best approach to suit their needs. This facilitated a two-stage underpinning process aligned with Stella Rossa Design and Build Ltd.’s preferences, ensuring full compliance with industry standards.
  • Enhanced Safety and Buildability: Reduced excavation depths to manageable 2.5-metre stages, significantly mitigating risks associated with deeper excavations, including potential ground movement and instability.
  • Maintained Structural Integrity: Ensured the stability of the existing structure and neighbouring properties throughout the construction sequence through rigorous monitoring and compliance checks.
  • Demonstrated Innovation: Applied an unconventional approach to basement construction, necessitated by the unique permanent works design, showcasing our ability to adapt to complex project requirements while delivering effective solutions.

 

“We had the pleasure of working with Independent Design House Ltd on this project, and the experience was nothing short of exceptional. Their team demonstrated outstanding professionalism, creativity, and attention to detail at every stage of the project. From the initial design concepts to the final execution, their commitment to quality and solutions significantly contributed to the project’s success. Independent Design House Ltd not only delivered impressive results but also fostered a collaborative environment that made the process enjoyable and seamless. I highly recommend their services to anyone looking to elevate their design projects.” – Stella Rossa Design and Build.

 

Contact Us for Your Next Project!

Are you navigating the complexities of basement construction? At IDH, we specialise in constrained temporary works designs that guarantee structural integrity and safety. Let our expert team assist you in overcoming the challenges, just as we did on this property in London. Contact us today to discuss your project requirements.