Issue 82Charting the stones at Bath Abbey

Architect Alex Morris charts the careful process of the recording, lifting, repair and relaying of Bath Abbey’s historic floor.

Made up of approximately 2400 floor stones including 891 inscribed ledger stones, the Bath Abbey floor has more memorial stones than any other church or cathedral in the UK.

The church burial registers, between 1600 and 1845, provide a record of approximately 7000 burials beneath the Abbey floor.  It is the deterioration of these burials that has caused ongoing subsidence, which has led to the collapse of the subfloor and the fracturing of many floor stones.

The Bath Abbey Footprint Project was initiated to repair the failing floor, but goes beyond that remit, to document and research the carved gravestones that make up the floor, record the archaeology beneath the stones and install an innovative sustainable heating system to provide comfort to parishioners. By repairing the building and providing flexibility required for contemporary uses the Footprint Project helps to secure a future for the Abbey, as one of the finest and most significant buildings in the south west of England.

Trial Works

A trial was undertaken in 2013, to understand the works and to test strategies for repair and rebuilding of the Abbey floor. In the North Aisle, the Victorian pews and plinths were removed, giving the first inspection of the floor stones beneath the pews for 150 years. The stones were carefully cleaned and the inscriptions on the floor stones were recorded. This revealed the stone layout as recorded in the 1870s floor survey - completed after the last major works on the Abbey by Sir George Gilbert Scott. The floor stones were carefully lifted and the floor slab removed. Excavations and archaeological investigations were then undertaken.

During the previous restoration works by Scott (1860-1873), the whole of the floor had been lifted and rebuilt, incorporating a new heating system. Archaeological investigations revealed that these works had only disturbed the ground 1m beneath the Abbey floor. The planned floor works for the Footprint Project restricted activity to the zone of previously disturbed soil, thus allowing the undisturbed archaeology beneath to be protected.

Inspection of the floor stones during the trial revealed that the floor stones remained largely untouched since the Scott works. However, it also revealed evidence of decay and the need for significant repairs. These repairs would be required to create a floor surface that would be fit for purpose for the next 100 years.

As elsewhere in the floor, very serious fracturing was evident in some of the floor stones. Heavy surface deterioration was also seen, with the resultant loss of inscriptions on carved stones. There was also heavy staining to some of the stones, caused by tannins from the timber pew supports. This was particularly evident on the white marble stones that are a notable and striking feature of the Abbey floor.

The trial works also provided the opportunity to establish a suite of repair techniques, to deal with the various types of floor stone defects.

After consideration of many options and consultation with Historic England, The SPAB and the Diocese, the structural engineers developed a design for a new concrete floor slab. This new floor slab was to be constructed within the previously disturbed 1m zone and designed in a way that accepts the inevitable further collapse of the sub-soil beneath, without affecting the new floor.

No more draughty Churches

Having decided to lift the Abbey floor, this created the opportunity to enhance the way that the Abbey is heated. The Victorian heating system consisted of heating pipes, set beneath cast iron floor grilles, as was common for the period. The use of this type of system in large volume buildings results in uneven heating at low level, as well as cold downdrafts from the large areas of glazing, which contributes to uncomfortable conditions in cold weather and inefficient use of energy. A new sustainable underfloor heating system has been incorporated in the design of the Abbey floor, powered by hot spring water ( read more in Explore 6: Just add water) This is supplemented by fin tube heaters, located in new trenches, beneath the reused Victorian cast iron floor grilles.

The new floor layout

The main floor works were undertaken in three phases, to allow the Abbey to continue to function on a day to day basis. During each phase of work, an evaluation process was undertaken which summarised the results of the individual stone assessments. Any stones that were irreparable or otherwise unfit for reuse were identified and the remaining stones were then used to create a new floor stone layout.

The objective of the new floor layout was to place the floor stones as close as possible to their original position. This would minimise changes in the floor pattern and also avoid cutting stones unnecessarily, as despite appearances they do not fit together in a regular pattern. However, there were a number of reasons why floor stones could not be re-laid in their original position.

The arrangement of floor trenches was altered in the nave, to counteract the strong downdrafts from the large clerestory windows and in the central choir aisle, the floor grilles were no longer required. While previously the stones of the entire central aisle had been staggered between two lines of floor grilles, they could be now aligned, acknowledging the importance of the central east-west axis of the building.

Electrical trunking was incorporated in the floor around the base of each column and concealed by new, removable stone covers. Other smaller changes to the earlier floor layout were made, to avoid the adverse visual impact of floor grilles and to incorporate new floor access panels. New stone was only added where absolutely necessary.

The resulting new floor layout is the culmination of thousands of individual stone assessments and many years of technical work by the specialist project team which then allowed the floor stones to be carefully re-laid, after construction of a new floor structure.

The removal of the nave pews at Bath Abbey and the repair of the historic Abbey floor provides an opportunity to appreciate Bath Abbey in a new way, reminiscent of the pre-Victorian era. The floor and wall memorials can be fully appreciated, enhancing the significance of the Grade 1 Listed Building. The evidence of lives lived in Georgian times also enhances the outstanding universal value of the City of Bath World Heritage Site. The corporation stalls and choir stalls are being returned to the east end, an important part of the Victorian history of the Abbey, but the rest of the pews will be replaced with stackable chairs that can be arranged to suit the wide range of activities that take place in the Abbey, providing much-needed flexibility for contemporary worship and community events.

Alex Morris

Alex is an Associate at FCBStudios. He is a specialist in creative reuse and heritage projects, and has been project architect on the Bath Abbey Footprint Project since 2015.

The Footprint Project is a £19.3 million programme of restoration, building works and interpretation that will secure the Abbey’s physical future and improve its hospitality, worship and service to the city and beyond.

Images

1. Memorial Stones laid into the walls and floor of the Abbey c. James Newton
2. Original layout of the ledger stones
3. Relaying the stones, after repair
4. Final arrangement of the ledger stones after restoration
5. Relaid floor c. James Newton
6. Artists impression of the Abbey after completion, with flexible seating set out for traditional worship
7. Bath Abbey c. James Newton

Keep reading, or go back