What this project did… Leicester Cathedral by van Heyningen and Haward Architects | Characteristics

vHH Leicester Cathedral 1

This year’s AYA judges were impressed by the work of van Heyningen and Haward Architects (vHH), as the firm was named a finalist for two awards, including Net Zero Architect of the Year (in partnership with UKGBC).

In this series, we take a look at one of the team’s entry projects and ask corporate partner Josh McCosh to weigh in on some of the biggest specification challenges that needed to be overcome.

vHH Leicester Cathedral 5

What were the biggest specification challenges of the project?

The Cathedral Revealed project in Leicester has two very different components: reordering the historic cathedral, refurbishing its fabric and replacing its building services; and creating a small extension.

The extension to the cathedral provides all the facilities that are needed but cannot be provided in the historic building: storage, toilets, baby changing, volunteer and ranger’s room, orientation gallery and education base. The building replaces a 1930s vestry block on a very small footprint, so space is created by building up and down, with two underground levels. One might think of it as a small, functional iceberg.

The biggest challenge was finding ways to get consent from the Cathedrals Fabric Commission for England (the statutory authority of the Church of England) and the local planning authority. As one might imagine, they did not quite agree. Judicious specification was fundamental in this, with much debate ultimately leading to our consent.

vHH Leicester Cathedral (2)

What were the key requirements of the client’s brief? How did you come across both in terms of design and specs?

The brief sought a transformative change: to make the cathedral suitable for contemporary worship, host a wide range of public and civic events and offer a warm welcome to all its visitors. The project follows our 2008 masterplan and our subsequent project to reinterpret Richard III and reorder the chancel and create his tomb – and aims to reorder the rest of the cathedral.

The first challenge was due to the nature of the building, a Grade II listed medieval church, much rebuilt in the 19th century and raised to cathedral status in the 1920s. With Richard III’s work we were able to move the high altar but the building was no longer fit for purpose: a single acoustic environment, no storage, no public toilets and no other facilities. The lighting was poor and other building services were in desperate need of replacement.

We had to adapt the floor to provide step-free access to the eastern parts of the building. We took this opportunity to make it as good as possible: it carries all the service infrastructure, provides efficient heating, and its gentle slope overcomes level changes. Specifying a pale limestone pattern finish subtly draws one’s eye to the east, unifies the congregational space, increases the amount of natural light and is robust and attractive.

vHH Leicester Cathedral 2

All materials specified are considered to be technically suitable for the historic fabric and avoid causing long-term risks. The stone floor is laid on a lime concrete substructure which reduces the moisture-vapour load on the existing fabric. The paneling changes are made of oak. Lime plasters and lime-based paint are used for wall redecoration and the specification strives to be ‘like-for-like’.

The second part of the challenge was very different, although it overlapped with the first. The shape of our new building was constrained by its site and the cathedral windows, so the major issue was ensuring adequate insulation and airtightness in a very complex building form. Faced with strong opposition to creating Passivhaus certified by the Cathedrals Fabric Commission for England (CFCE), we were ultimately asked to design as close to Passivhaus standard as we could get permission for, within the budget.

Below ground, this led to intense three-way design coordination between vHH, Price and Myers (structural engineers) and Etude (Passivhaus consultants) to create a two-story basement very close to the deep medieval foundations of 600mm of the cathedral – and still achieve waterproofing, continuous insulation and air tightness criteria.

Above ground, all interfaces and facade materials were constrained by the need for the building to relate well to the historic fabric both technically and aesthetically. This led to the specification of stone walls, with copper and lead roofs, like the cathedral, but in a distinctly contemporary manner. However, these facades and roofs have Passivhaus insulation levels and an air barrier designed to achieve < 1.0 m3/m2/h at 50 Pascals (Pa).

All specified materials are considered to be technically suitable for historical material and avoid causing long-term risks.

What did you think was the biggest success of the project?

The first section of the project is complete and the new extension is due for completion in late summer 2024. Without the benefit of feedback yet, we are most pleased with the new floor and how it has enabled us to solve multiple challenges while improving the whole feel of the cathedral.

It allowed generations of cables and “temporary” ramps to be removed from the interior, allowing everyone to move smoothly through the space and directing it slightly to the east as they entered. The beautiful Purbeck, Ancaster and Hopton Wood limestones in the floor pattern enliven the space and reveal the fleeting colors of the cathedral’s wonderful 19th and 20th century stained glass windows as the sun moves.

We hope that the new extension will be truly transformative in the life of the cathedral, enabling a much higher standard of operation and enhancing its reception and expansion. Its quality will help minimize operational emissions and hopefully also convince the various statutory bodies that using Passivhaus methodology is not inconsistent with building a listed building.

vHH Leicester Cathedral 4

What are the three biggest considerations of project type specifications? How did these specifically apply to your project?

The project is a composite of a low energy building using the Passivhaus methodology and a heritage retrofit project.

Passivhaus is construction-independent, in that any strategy is allowed as long as the airtightness and insulation values ​​are met and the plumbing, windows and other critical components are good enough.

The performance of materials and techniques is essential to heritage modernization as it mitigates damp risks to the historic fabric and preserves the building for the future.

Within the historic cathedral and for changes to its fabric, the techniques and materials chosen are specified so as not to damage what is there. These are generally versions of existing materials and the details aim to minimize risks and keep moisture out of open construction.

By extension, the need to meet Passivhaus performance levels led to an intensive analysis of materials and components so that we could select those that performed properly, were compatible with the behaviors of the old fabric and with the building and heritage significance or. .

For both reasons, the main consideration for the specifications was the suitability of the components and materials to their particular situation. These judgments, including the resulting pre-application discussions with CFCE and APL, were among the most challenging aspects of the project.

Project details

Architect van Heyningen and Haward Architects

Our What Made This Project series highlights the outstanding work of our Architect of the Year finalists. To keep up to date with all the latest from the Architect of the Year Awards, visit here.

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