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Retaining wall rescue

Type of work: Ground anchors and masonry reinforcement combine to restrain overturning the listed retaining wall

Location: North West London

The presence of a tree behind this retaining wall in North West London had created significant problems when root growth created lateral pressures resulting in bowing of the brickwork, and overturning of the wall. Built in soft bricks with lime mortars, the wall is within a Conservation area, and consequently listed. Because of this, wholesale demolition and reconstruction of the wall was not an option, and an alternative approach was therefore required. Additionally, the rigid requirements of the appropriate authorities needed to be taken into account in providing an adequate but sympathetic repair solution.

 

Where the existing brickwork had fractured and been dislodged beyond making good in-situ, it had to be removed prior to rebuilding. Previous making good with cement mortars resulted in the loss of many bricks, but careful sourcing of matching second hand replacements ensured that the homogenous appearance of the wall was maintained. Traditional lime mortar was also used in the re-construction of the wall, followed by toning down to match the original areas. The entire length of the wall required the introduction of lateral restraint, and this was provided by the installation of stainless steel Duckbill MR3 ground anchors, driven 4 metres into the ground behind the wall, through diamond cored holes in the 230 mm. thick brickwork.