Timber is the star at Eton’s pool and sports hall

Eton College Sports & Aquatic Centre

A timber structure clad in brick, Eton Sports & Aquatic Centre has become a much-loved asset to the College that’s also used by the local community.

The project came to Hopkins architects after they’d made a good first impression via a previous competition entry. They hadn’t won, but it had opened a door.

When Eton College required a new swimming pool in a part of the campus that was off the beaten track, they approached Hopkins. A site had been identified for the new pool – where a redundant and dilapidated outdoor pool sat, unused.

Eton College Sports & Aquatic Centre timber framed pool

The ground-level pool and generous daylighting connects swimmers to the world outside; image © Janie Airey

It was here that a new 25m pool and four-court sports hall was to be built. The job was undertaken by Hopkins under the project leadership of Andy Barnett, one of Hopkins’ Principal Architects.

Inspiration from the past
The completed facility consists of two main venues, the swimming pool and the sports hall, and, between them, a narrower connecting part with a viewing platform and café.

There is a long tradition of outdoor swimming at Eton, explains Andy Barnett. The new pool takes its name – ‘Athens’ – from a bend in the Thames where Etonian pupils once used to swim. The site also had some of the qualities of a ‘secret garden’, he continues. It sits apart from the main College : through a gate, to a clearing surrounded by trees.
“In order to build the original outdoor pool they’d dug a large excavation,” he tells us. “They formed a bund – a mound about a metre high – all around wooded site.”

Taking it down a level
The site was in the Green Belt, so the height of the building was an important consideration. Hopkins Architects decided to sink the building into the ground, which brought the pool down to the same level as the garden outside. Both the pool and the sports hall were given flat roofs, which kept their level beneath the trees.

This reduced the visual impact of the building mass on the open land beyond it and provided an extra feeling of being connected to the landscape for the pool’s swimmers. It also made the building more accessible: from the front entrance, you can get to the changing rooms and pool without changing floors.

Exterior of Eton College Sports & Aquatic Centre

Exterior of Eton College Sports & Aquatic Centre, showing the brick facade.

Glulam and CLT: providing the structural strength
Andy had previously worked on a large sports hall project in the USA: Colby College Athletics & Recreation Center. This had been a valuable learning experience for him.

“You quickly appreciated that, with such long-span structures, you have to think about efficiency and economy. If it’s not as light and efficient a structure as it can be, you will pay a significant premium. Glulam and CLT make very good material choices.”

The main supporting structure of the two halls consists of spruce glulam columns with overlying glulam beams. The glulam beams in the swimming pool span over 31 metres and, in the sports hall, 18 metres. The secondary supporting structure is made of CLT elements, which span over the beams in multiple spans of approximately 4 metres. The timber was supplied by Wiehag. For timber preservation reasons, the column bases were clad with steel shoes and all metal fixings were corrosion resistant.

Brick and timber: they play well together
From the outside, you might not appreciate the amount of timber in the building. “It had to complement the architecture of Eton college,” Andy points out. “The cladding is a sand-coated brick with a gap between the brick and the glulam. So essentially it’s a brick box wrapped around a glulam box”, clearly differentiating between structure and enclosure.

This space between the two also allows a spectacular play of shadow and light on a sunny day enabled by large windows and rooflights cut into the envelopes of both venues. This was offset by carefully designed shading louvres to prevent glare, especially in the pool, where it is important that lifeguards have good visibility.

A space to enjoy, not just to exercise in
The building is approached through a walled and landscaped courtyard. A double-height arrival space leads either up to the sports spectator space, down to the sports hall, or into the changing areas. The spectator area is a transparent ‘link’ which connects the two venues, linking the formal front courtyard with an informal garden to the rear.

At the spectator gallery, the soft curves of the wooden seating was inspired by the benches on Mersey ferry boats. They’re made of ash, as are other elements of the joinery; while all the paneling is birch-faced plywood.

Curved ash timber seating, Eton Sports & Aquatic Centre

The curved seating in the spectator gallery was inspired by that of the old Mersey ferrey.

Andy points out that sports halls are a unique building type: they may be large and utilitarian, but they are not industrial sheds. The experience of using them can be atmospheric as well as functional.

“The spectator gallery is designed as a place to meet and spent time in addition to watching an event.” he states. “Often, interstitial spaces between sporting venues are just dark, circuitous interiors.”

Getting the acoustics right
The sports hall is also used for exams, so it was imperative that noise in both halls was carefully controlled.

“In a pool it’s all hard surfaces,” Andy says. “We need as much sound absorbency as possible – so both ceilings and one entire wall in the pool are timber with slats with acoustic felt behind.”

Sustainability considerations
The College were clients enthusiastic to address sustainability concerns, and various measures were taken to address embodied and operational carbon.

The mass-timber interior of the sports hall at Eton College Sports & Aquatic Centre, with boys playing basketball.

The sports hall is also used for exams, and was carefully designed with multiple functions in mind.

Timber is, of course, a low-carbon structural material to begin with. A BMS system in the hall operates windows to maximise natural ventilation, while the pool requires MVHR (mechanical ventilation with heat recovery).

The roof of the pool houses photovoltaic panels and the hall has a green roof. Existing mature trees outside provide shading to prevent overheating.

A facility open to the community
The brief required that the facilities could be used by the wider community beyond the College. There are therefore two sets of changing rooms. One is designed to be split in two for use by competing teams the other more standard male and female changing rooms.

“One end of the pool has an entirely movable floor level to adjust the depth,” Andy reveals. “It can be lowered for competitive events or raised so that it’s only 3 feet deep for swimming lessons.”