Shire was appointed to deliver a value-engineered remedial solution to a critically defective retaining wall foundation on an active new-build housing development, preventing costly partial demolition and protecting a complex programme.
Shire was appointed to deliver a value-engineered remedial solution to a critically defective retaining wall foundation on an active new-build housing development, preventing costly partial demolition and protecting a complex programme.
The Challenge
During a further phase of a UK national housebuilder’s development at Lubbersthorpe, a routine design check revealed that the retaining wall foundation toe had been accidentally reduced from the specified 700mm projection to just 550mm, a seemingly small discrepancy with serious structural consequences. The reduced toe meant ground bearing pressure beneath the footing exceeded the allowable limit for the site, raising the immediate prospect of partial demolition and replacement of the wall.
The structural stakes were high. In close proximity sat a substation, an external stairwell, garages and adopted roads, all of which would be affected by demolition works, creating high cost and programme implications for the main contractor.
Further investigation compounded the concern. Exposed reinforcement was discovered in the base of the foundation, and in areas where diamond coring had been carried out, anticipated reinforcement bars were absent entirely. Taken together, these deficiencies rendered the foundation unfit for purpose. Under these conditions, excavation and construction of the foundations for the adjacent housing plots could not safely proceed.
The Shire Solution
Shire carried out a detailed investigation, including sample cores, to establish whether the retaining wall had been built as designed and to confirm whether sufficient reinforcement existed within the precast core to satisfy design checks. The findings were decisive: by extending the reinforced concrete projection, the wall could be made to resist any potential overturning moment, eliminating the need for demolition entirely.
The defective RC projection was fully excavated and exposed, and all defective reinforced concrete was carefully removed. New reinforcement was installed and bespoke formwork erected, precisely configured to cast the concrete required to form the RC toe to the correct specification. The new reinforcement was designed to integrate fully with the existing wall structure, ensuring composite behaviour and long-term durability.
The Outcome
The remedial works were completed within just four working days, unblocking the programme for the adjacent housing plots, protecting the surrounding infrastructure, and delivering substantial cost savings to the main contractor compared with the alternative of partial demolition and reconstruction.
