Workshop walls: progress report
It’s been a week or two since we’ve updated you on the works to the workshop walls, and work is progressing well.
General repairs are still being undertaken, along with preparations for the new facing. A foundation trench has been excavated as part of these works to allow a drainage system to be installed.
This trench, which will be filled once the wall is complete, is needed because the new façade will create a cavity between it and the carcassing brickwork – in many ways similar to a cavity wall construction in a home – and rainwater will naturally seep into this. To allow the moisture to drain away some vertical joints in the brickwork will be left open below ground level.
The next picture shows two large steel beams. Called needles, these allow the granite above the new façade to be supported. Needling with small beams is often used when you open up a new doorway or window in an existing brick wall. As with everything on the Old Bridge, we have gone large with the needle beams, in order to support the huge weight of the stone blocks above.
A trick of the trade being implemented during all this work is the use of grout tubes. In order to inject grout deep into the gap between the brickwork and the stone parapet edge beam or ‘string course’, holes are drilled into the gap and sections of hosepipe are inserted. Grout has then been injected into each section using a hand pump. Once enough grout has been injected, the pipe is then bent in half and secured with a cable tie to stop it seeping back out again. The grout is then left to ‘cure’ (a chemical reaction where the grout hardens and dries). The grout allows the string course to be fully supported on the carcassing brickwork, ensuring the integrity of the wall.