North aisle floor work
Recent archaeological excavations have confirmed that there are a number of large voids beneath the Abbey floor, causing it to collapse and putting the structure of the building at risk. In some areas the floor is already starting to sag.
Last Summer, trial work on the floor began in a small corner of the Abbey - in the North aisle. After months of restoration work, the work was completed in November 2013 and the North aisle, which makes up 5% of the Abbey's entire floor, was successfully repaired - saving it from collapse. This area was also fitted with underfloor heating pipes that, as part of a partnership with Bath & North East Somerset Council, will eventually be fuelled using waste hot water which flows from the Roman Baths next door.
The new heating system is now being monitored in order to measure its effectiveness with different floor surfaces. Two-thirds of the floor in this trial area have been recovered with the original ledger stones while the final third is covered in new stone.
The findings and methodologies from the North aisle floor trial will be essential in enabling us to repair the whole of the Abbey’s floor and to install underfloor heating throughout. The rest of the floor will be done in 2015-2018 - it's a big floor!
THANK YOU to the Coles-Medlock Foundation and Brian and Margaret Roper for their generous support of the floor work.
Click here to view a slideshow showing the different stages involved in the floor trial.
Four final year Physics students from the University of Bath replicated a section of the Abbey’s stone floor and new underfloor heating system in laboratory conditions, and conducted a feasibility study into the efficiency of the scheme. In order to do this, the students tested the water temperature against seven different floor types of varying materials and thickness. The results of these trials were written up in a report which is now being used to help in the final design of the system.
Underfloor heating pipes were successfully installed in the North aisle and carefully covered with a layer of screed before the stone flooring was replaced. The exciting part is, once we have a stable floor we are going to use it as a huge radiator!
Over 2,500 litres of grout were poured into the ground underneath the North aisle. This filled the massive voids beneath which were what were causing the Abbey's floor to collapse. The grout was methodically and carefully poured by hand rather than pumped. One void was filled with over 119 litres or 26 gallons of grout – the voids under our floor are very big!
Once the voids were filled, the floor was brought back up to its original level and a layer of concrete was laid. The next stage of the process will be to install the under floor heating system, and eventually lay the stone floor.
The ledgerstones making up the stone floor in the North aisle were lifted up and removed. This enabled the construction team to begin preparing the ground which included digging down to about 1.2 metres below floor level. Further archaelogical investigations took place and a ground penetrating radar was used to assess the voids .
The first step was to remove the Victorian pews in the Abbey's North aisle. As a result, many of the historic ledgerstones which had previously lain hidden under the Abbey’s 19th century pews were exposed for the first time in 140 years. This presented us with the rare opportunity to fully record these previously unseen ledger stones.
In just four days (including one day of training) volunteers from the Abbey and NADFAS (National Association of Fine and Decorative Arts) cleaned, recorded and photographed over 100 ledgerstones.
Over 400,000 people visit the Abbey every year. It is in daily use for prayer, worship, and community activities. Despite the problems with the floor, we want to keep the Abbey open and available to all. During the North aisle floor trial, we will be fixing 5% of the floor which means this area will be temporarily covered by hoarding and out-of-bounds to the public. At the same time, we will be trialing a new entrance and exit doors in the South West, and a temporary welcome desk.