Durham Cathedral's Open Treasure project
|Durham Cathedral’s hidden treasures included architectural spaces and artefacts from its collections.|
Durham Cathedral, the most significant and complete Romanesque cathedral in Europe, retains a near-complete and intact range of Benedictine claustral buildings. The cathedral houses the largest in-situ collection of medieval manuscripts and early printed books of any English cathedral.
Chris Cotton, cathedral architect and partner to Purcell’s York Studio, led his team in the delivery of an extensive programme of works known as Open Treasure. These works were agreed following research to understand the complexity of the project, and to define the brief and priorities. The process included extensive expert research, coupled with programmes of consultation and public engagement.
The dean and chapter’s ambition was to widen public access to the cathedral’s hidden treasures, including architectural spaces as well as pieces from the collection. This became a Heritage Lottery Fund project, with other funding streams supporting the project. It included a scaled Lego model of the cathedral.
The project’s biggest challenges lay in four spaces which surround the cloisters: the Refectory Library; the Collections Gallery; the Monks’ Dormitory; and the Great Kitchen. Despite their outstanding value, they were mostly inaccessible and required urgent repairs. The project elements which were intended to form new exhibition and library facilities also had to deliver new environmental controls, set in the context of a historic building constructed from porous materials and with extremely limited plant space.
Among other specialist and consultants, Tobit Curteis, David Odgers and TGA Consulting Engineers were appointed to work with Purcell to undertake the analysis of the existing condition, while creating sensitive and suitable solutions to manage environmental conditions. Due to the different uses proposed, each space needed its own bespoke approach, including its building services.
The quinquennial inspection and report published in 2013 indicated the requirement for urgent repair works and set out what management was to be expected. Once the brief had been agreed and the team appointed, the process began undertaking detailed trials, including sampling and materials analysis. This was in conjunction with an extended period of environmental monitoring by Tobit Curteis as specialist in environmental monitoring. TGA Consulting Engineers undertook detailed surveys of the existing engineering services to establish how best to approach the proposals while minimising the risk of loss of services and damage to the historic fabric.
Although known as a tourist attraction, the cathedral sits at the heart of the religious community, so any interventions had to be mindful of the site’s intended purpose. The events and services had to be minimally impacted throughout the project. An assessment was carried out of how building defects, historic and modern materials, water and moisture, heating regimes, and environment were combining to hasten the decay and failure of historic material. The four key spaces all had different defects, but they had the opportunity to become part of the visitor and user experience, allowing collections of which some were to be shown for the first time.
The Refectory Library contains the cathedral’s collection of rare early printed books, housed in the former medieval refectory, which was refitted in the early 18th century. This had become unstable. The environmental conditions, including humidity, temperature and ultra-violet light, had to be stabilised. These interventions have ensured the protection of the valuable books and manuscripts to be read in the adjacent space, a new Reading Room.
The Collections Gallery, where some of the most sensitive artefacts are displayed, now has a close control air-conditioning system. The new systems had to be carefully segregated from the historic building fabric. The conservation team specified passive display cases, incorporating silica gel in mesh bags, to work in conjunction with the environmental controls to achieve target conditions.
The gallery showcases precious artefacts in a state-of-the-art gallery, renovated with exceptionally high levels of environmental control and security. From the Collections Gallery a new stair and lift and opened passageway leads to the Great Kitchen Exhibition space. This required complex archaeology and dismantling of low-significance fabric, giving access to all for all the spaces for the first time.
The Monks’ Dormitory, one of England’s most significant medieval halls, dating back to the 14th century, is the country’s last intact dormitory. The historic room, boasting a long oak-beamed roof and large open spaces, presented itself perfectly to become the exhibition space displaying the cathedral’s collection, a narrative interactive exhibit and objects such as Anglo-Saxon stones.
A new lift was sensitively designed and installed. New services included heating and lighting systems. The heating system is controlled on conservation heating principles, with low temperature hot water supplied to perimeter radiators and finned heating tubes. These are supplemented by locally controlled heating at library desks and staff positions, as it is sometimes necessary to reduce the general heating of the room to maintain environmental conditions.
The Great Kitchen, also built in the 14th century, is a rare example of a medieval English monastic kitchen. The distinctive octagonal ceiling with rib vaults has become the home of the Anglo-Saxon Treasures of St Cuthbert display. The conservation project consisted of significant restoration of the decaying stone of the roof vault and walls, and innovative solutions tackling key defects to the space.
Tests had revealed that the space had a relative humidity of between 60 and 85 per cent, caused by moisture ingress through the fabric. This, and frequent changing air temperatures between 9 and 18 degrees, meant that magnesium sulphate salts, inherent in historic lime mortars, were being activated. This led to the crypto-florescent cycle occurring regularly between crystal and liquid states of the magnesium sulphate salts. This was causing damage to the UK’s only remaining stone-vaulted kitchen.
To control relative humidity and combat the decay, the Great Kitchen’s concrete slab floor was removed and replaced with a limecrete breathable one which incorporates a floor duct. The installation of a new conservation-focused heating system then enabled air to be ducted through the floor at low pressure over finned heating pipes.
The new environmental control system is a hybrid solution which includes close control air conditioning with plant located in confined spaces concealed in wall structures. The air conditioning has been set up so as to be able to dehumidify, if other means fail to adequately control the environment, but it cannot actively introduce moisture.
By improving and managing these conditions using traditional, conservation repairs, the new mechanical engineering systems have delivered stable and safe conditions for the fragile Anglo- Saxon silks, manuscripts and artefacts. The interior was also relit to display the architectural and archaeological qualities of the room.
The environment in each of the spaces is now stable and within target ranges enabling the rooms and their contents to be enjoyed by thousands of visitors. The relative humidity of the kitchen, for example, is now averaging 49 per cent, with temperatures that gradually change through the seasons to maintain this level. The oscillation of magnesium sulphates has been stabilised. As a result the cathedral is now able to display in passive cases the Anglo-Saxon-period silks, early medieval manuscripts, and the Anglo-Saxon coffin associated with the shrine of St Cuthbert.
|Installing air-conditioning in the Collections Gallery enabled the display cabinets to rely on passive environmental controls alone.|
This article originally appeared as ‘Servicing Durham Cathedral’s Open Treasure project’ in IHBC's Context 159 (Page 28), published in May 2019. It was written by Louise Priestman, a conservation accredited architect who works for Purcell Architects.
Related articles on Designing Buildings Wiki
- Building a Crossing Tower: a design for Rouen Cathedral of 1516.
- Building services.
- Cathedral of Brasilia.
- Cologne Cathedral.
- Dunelm House, Durham.
- Florence Cathedral.
- IHBC articles.
- Sourcing stone to repair Exeter Cathedral.
- St Pauls Cathedral.
- St. Basil's Cathedral.
- The Institute of Historic Building Conservation.
Councils are reported to be considering taking up rarely-used executive powers to keep the planning and development system moving during the coronavirus pandemic.
Historic England's 'After a Flood' provides timely advice on how to dry walls properly and avoid further damage to the building fabric.
Context Issue 162 offers a peek into an archive of timber conservation history through the records of the practice of FWB and Mary Charles Chartered Architects.
To meet the government’s target of being carbon neutral by 2050, we must recycle, reuse and responsibly adapt our existing historic buildings, according to this year’s Heritage Counts report, so Historic England and partners are calling for a reduction in VAT rates to incentivise this more sustainable option.
Donald Insall Associates, with the help of Historic England, has completed restoration work of Moseley Road Baths, being converted for use as an arts and culture venue.
Celebrate your local ‘retired members’ and ‘successful learners’ with £500 cash prizes and 2020 Brighton School places!
The Conservation Hierarchy is a new framework developed by the University of Oxford to help construction projects achieve Biodiversity Net Gain.
Jacqueline Hughes, senior risk analyst at Equib, in pbctoday discusses how project managers for town centre developments can get their risk management strategies right.
A new paper from the Adam Smith Institute argues that the problem with the High Street has been totally misunderstood, saying that we need to reform restrictive planning rules and reject a policy of managed decline to reinvigorate our town centres.
The Whole Life Cost of Energy (WLCoE) calculator – issued by government in BETA form – is intended to help building owners and operators to understand the full financial cost of the energy their buildings use, and welcomes feedback
New research published by Historic England (HE) shows the value of heritage to England’s economy as it contributes to economic prosperity and growth through jobs in the heritage and construction sectors and from tourism.
Investigations have begun into what caused part of Chester’s Roman city wall to collapse during construction work.