Stirling Prize 2024 shortlist: Park Hill Phase 2, Sheffield, by Mikhail Riches

The Brutalist Park Hill estate, commissioned by Sheffield City Council architect JL Womersley in the 1950s, is the largest building in Europe. Originally intended as a ‘streets in the sky’ concept, it deteriorated into a sink estate – its architecture, perhaps unjustly, blamed.

Park Hill was saved from demolition by the Grade II* listing of its concrete frame; three of its 'wings' were redeveloped in Phase 1 by Hawkins\Brown and Studio Egret West for Urban Splash, earning a Stirling Prize nomination in 2013.

Phase 2 saw Mikhail Riches regenerate the central section of the estate, creating 195 flats and 2,000m² of commercial space. It is a lighter-touch renovation, intent on preserving the original structure and prioritising energy efficiency.

Unlike Phase 1, with its distinctive coloured panels, Phase 2 retains the original brickwork infills, instead providing individuality via coloured insulated panels on the balcony reveals. The palette takes its blues and greens from the nearby Peak District.

Flats have been reconfigured to meet modern space standards, with a variety of options for both private and social tenants. Throughout, thermal efficiency, concern for embodied carbon and security have been prioritised, creating a comfortable living environment while fostering the sense of community found in Jack Lynn and Ivor Smith’s original designs.

Let’s begin with how the design process developed

Annalie Riches Urban Splash launched a competition to find a new architect after Phase 1, with a slightly different focus of retaining more of the listed building. It was quite an unusual competition because it gave every architect an apartment to look at over two weeks; then the jury was invited into those flats and we showed them our ideas.

We were allowed to wander round the derelict building, which led us to notice a lot of traces left by people, what they had done to their flats to make them into homes, such as painted balconies and fragments of lino on thresholds. They wanted to create a sense of individuality in what is a beast of a building.

We had to think really fast about our approach, so it’s interesting that the building looks pretty similar to what we drew at the time.

Also, because I knew the building quite well from having been a student in Sheffield, I really, really wanted to keep the bricks. Having decided that, it set the parameters for other decisions, and everything else cascaded from there.

Were there any particular constraints which informed the design?

The constraints of the building are quite specific: it has been listed for its concrete frame. We had a more retentionist approach, meaning that keeping the bricks became a constraint.

We tried to give them the same relevance that the panels had on Phase 1. That then set up the design for the window reveals and the palette of materials and colours, which needed to not compete with the bricks.

It actually took quite a long time to convince Historic England it was a good idea because it differed from Phase 1. That was a discussion I wasn't expecting to have, to be honest. Those bricks were in really good condition! They’ve been there 60 years, were very dirty, but we didn’t even need to repoint them, just give them all a good clean.

How did you choose what to prioritise in such a complex project?

I think the answer is that the whole project was an activity in choosing which small changes to prioritise to make liveable and comfortable homes. It’s not a ‘big move’ building. It was when it was built though.

Technically the priority was resolving the cold bridging. We were dealing with a cold, wet concrete structure. Because it was listed and had to be revealed on the outside, we had to insulate every surface of every room, with very restrictive floor-to-floor heights. We worked closely with the consultant on a thermal model with the result that there are multiple specifications of insulation in each room.

There was no standard way of doing a project like this. There were micro-decisions everywhere, to do with acoustics, warmth, privacy, safety and avoiding condensation.

What were some of your main influences?

I really wanted to win the competition because this quite an important building for me. When I was a student, this building was considered a complete failure, but it was also a key building to admire; there was always that conflict. It’s probably the building that made me want to get into housing, at a time when there weren’t many people who did.

It is a building with a lot of baggage; there are so many points of reference, and we wanted to do something that respected the original design intent and Phase 1. So much of it was also about observing what people had done to their homes in the past, so there are lots of these kinds of influences to acknowledge.

There is also a definite trajectory from Le Corbusier’s Unité d’Habitation, as well as JL Womersley’s ethos about taking people away from cars to promote community. It’s something he felt very strongly about.

Tell us about some of the challenges you faced

It’s a really complex building. We had assumed there was a repetitive cluster of flats. Actually there are 37 different types – a mad configuration, and no repeating cluster.

It’s not even drawn the same way that you would draw a normal building. In the office, we have had to keep the same team on it because it takes weeks to understand, not to mention the strange jargon associated with it.

We had to mark up every front door for the builders. On one occasion we had a window sample put in and we were standing outside looking at it. When we went in, it took five attempts to find the flat we were after – and we knew the building well!

It also didn’t help that it was built during Covid. We had materials stuck in a boat on the Suez Canal or quarantined. Every day there was something, material delays and people going off sick, lots of trades working over each other at the end. Alim Saleh, our project architect, lived in Park Hill for a month so he could go to site every day.

What do you consider to be the project’s success?

It’s just delightful to be part of showing that actually this building was a brilliant design. The people that move in form this really strong community quite quickly. We’ve certainly tried to make the streets more overlooked while giving people a bit more personal space outside their front doors. There are so many small moves to try and alleviate some of the problems that the estate had. It’s been amazing to give Park Hill a new life.

See all six projects shortlisted for the 2024 RIBA Stirling Prize

Key data
Contract value £25m
GIA 16,810 m² 
Cost per m² £1,487

The 2024 Stirling Prize is sponsored by Autodesk