The Hostry, Norwich Cathedral, Norwich, Norfolk

Introduction

Hopkins Architects has been involved in the design of new facilities at Norwich Cathedral for 14 years; the first phase of development, the Refectory (the subject of a TRADA Case Study in 2007) forms one side of the Cloisters and the second phase, the now-completed Hostry, runs at right angles to it. The architectural objective was that ‘it should be clearly evident that the new Hostry and Refectory were built in our own age, yet carried forward the memory of the earlier buildings’.

The two developments are believed to constitute the single most extensive addition to an English medieval cathedral since the Reformation. The design drew on historic precedent, responding to immensely complex heritage, archaeological and ecclesiastical planning issues, including responding to the strictures of the Grade I listed site and the Cathedrals Act. It also emphasises the hospitable and educational ethos of the Benedictine order and contributes to a reanimation of the cloistered site as a whole.

Building description

The buildings form two sides to the Cloisters, occupying the original sites of the Refectory and the Hostry and taking advantage of the original walls where possible. The new Hostry, traditionally the place of welcome for pilgrims in the Middle Ages, is entered through the medieval Hostry arch and its rear wall is the original west Cloister wall. It accommodates visitor facilities - an exhibition area, a flexible education room and conference/community room; it also houses the Cathedral’s Song School and choir rehearsal spaces.

Both buildings had been built as halls – the Hostry with upper chambers at each end - and the design endeavoured to retain that sense of a single medieval hall volume. As the architect explains: ‘Conceptually the upper floors can be seen as large pieces of timber furniture, detached from the surrounding stone walls, so that, from the ground floor, it is possible to see through to the roof. This analogy resonates with the way that, in medieval halls, secondary elements, such as rood screens, lofts and galleries, were effectively large-scale pieces of furniture, within enclosing masonry walls’. Hence the interiors are characterised by large, open-plan spaces with the potential for future change of use, a spatial versatility which will help to sustain the Cathedral’s economic, physical and social development in the long term and reinforce its Benedictine ethos. With three minimal and subtle changes to existing openings, and only two new ones, the new buildings open up the entire Cathedral precinct for disabled access. A new lift at the rear gives access to all levels.

Structure and materials

The architect’s aim was to create buildings which, both in concept and fabric, would be welcoming, suit their historic surroundings, and last: the client required an exceptionally long design-life of at least 100 years. Long-life, durable and self-finished materials were chosen to allow the buildings to age gracefully and be straightforward to operate and maintain.

The structural materials palette is dominated by solid oak, with fine steel-tipped finger-props holding the sand-cast lead roof, whose very stiff diaphragm is formed of glulam beams, steel purlins and plywood sheathing. The roof and first floor loads are carried down a grid of flitched oak columns into minimal pad foundations. Although similar to the Refectory columns, the Hostry columns required precision engineering to accommodate the additional loads of the first floor as well as the roof, resulting in the addition of a series of cruciform steel flitch plates at the sides of the columns that support the first floor, the oak and steel working compositely to provide stiffness and support within the minimum possible diameter. The advantage of this structural strategy is that no loads are placed onto the existing fabric by the roof; the first floor of the Hostry cantilevers out from the columns towards the east and west walls so that they only take minor horizontal loads. The floor beams are set in deep steel ‘pockets’ recessed into these walls with slip joints, which direct forces in line with the walls to brace the frame longitudinally. The beams support glulam joists and a plywood deck above and below. The cantilevered floor tapers to glazing at the perimeter so that a line of light separates new from old.

English oak, chosen for its quality and natural longevity, was used for soffit linings, with acoustic attenuation slots integrated into the panelling, window frames, solar shading louvres and other fixed furniture. Steel is used for cross-bracing in the end walls and for various items of architectural metalwork.

Sustainability

The new buildings were developed with an holistic approach to make them as sustainable and energy-efficient as possible within the constraints of their historic setting. In spite of complex historic restrictions and statutory designations, operational and environmental performance has been maximised. The carefully protected re-use of existing walls wherever possible has retained their embodied energy, thus keeping the use of new materials to a minimum.

Only minimal alterations were permitted to the medieval fabric, and major new elements of external walling were required to be built in traditional solid masonry. The remaining external walls are fully glazed with high solar and thermal performance glazing. External timber louvres and overhanging gutters limit solar gain to the interior.

In such an historically sensitive setting, it was necessary to employ ‘smart’ but relatively ‘low tec’ environmental measures; nevertheless, they have achieved significant energy efficiencies. Roof and floors are insulated and natural ventilation systems are used throughout. No air-conditioning is required, and mechanical ventilation is only used where absolutely necessary. Underfloor heating grids, connected to energy efficient gas condensing boilers with a weather compensation system, are used at ground and first floor levels.