UPDATED Residents of a landmark Roehampton housing block are worried after discovering a crack beneath their building — just days after emergency contractors were sent in to fix a major sewage leak that had plagued them for more than two weeks.
The area beneath Denmead House — part of the Alton Estate’s iconic modernist slab blocks — was cordoned off late last week. Residents say it followed more than two weeks of visible water dripping onto the concrete undercroft and pooling near support pillars. A large crack then appeared in a structural panel overhead.
On Sunday, a new panel appeared to have been installed in place of the damaged one — but no explanation has been offered. It’s not clear if the underlying issue has been fixed or if the damage is more extensive. One resident who checked the site after the replacement was carried out said it was still not clear “what’s going on under there.”
“We’re worried they think it’s unstable,” said another. “It’s not just the water anymore — it’s the building itself.”
On Monday, a large section of the underside has been cut out revealing the pipes and wiring, with metal barriers now in place, although some leakage is still noticeable with waste water continuing to pool up at the concrete supports.
The work follows two full weeks of sewage leaking into a vertical run of flats. Waste water had been dripping from ceilings, soaking through carpets, and forcing families to abandon entire rooms. The leak was finally stopped on Friday 23 May by the council’s contractor, Drain Surgeons. But photos and videos taken shortly after showed water still dripping beneath the building — and now a growing fear about the structural impact.
Despite repeated requests, Wandsworth Council has not provided any explanation. An inquiry sent by Putney.news on 21 May, as well as a follow-up a week later remains unanswered — echoing residents’ experiences of being ignored over serious concerns.
From bold beginnings to silent decay
The block is one of five monumental concrete slab buildings that make up Alton West, part of the wider Alton Estate in Roehampton. When completed in 1959, the estate was hailed as the future of public housing — a “world-famous” showcase of how modernist design could blend with the English landscape.
Inspired by Le Corbusier’s Unité d’Habitation, the five slab blocks were set within Highcliffe Drive’s preserved Georgian parkland, facing twelve slender point towers across the green. The estate mixed housing types — high-rises, walk-up maisonettes, family terraces, and even bungalow courts for elderly tenants — all arranged with libraries, schools, shops, and community halls to create a self-contained “estate village.”
Architects and civic leaders travelled from across the globe to see Roehampton. The vision was utopian: light-filled homes, social cohesion, and modern architecture in harmony with nature.
But today, tenants say the dream is being left to rot.
A failure of maintenance — and transparency
Residents say the leak and subsequent cracking are just the latest in a long list of maintenance failures. Several have reported years of delays on repairs, from pigeon infestations and fly outbreaks to blocked drains and water damage that was never properly fixed.
One long-time tenant recalled that it took three years to resolve flooding in her flat — and that she was falsely accused by the council of refusing access. “They left a card when I wasn’t home, then said I blocked the repair,” she said. “It wasn’t true.”
Another woman described watching her son throw away a freshly cooked meal because sewage began dripping into the kitchen from above.
“There are flies. There’s a foul smell. We don’t know what we’re being exposed to,” said one resident. “And now there’s a crack forming under the building and no one is saying anything.”
Prolonged water leakage inside concrete-framed buildings can lead to serious structural problems. When waste pipes fail inside the walls or floors, water can infiltrate concrete slabs and corrode internal steel reinforcement. Over time, this weakens the structure and can cause visible cracks or subsidence. If not identified and addressed properly, it can compromise the safety of entire sections of a building.
Wandsworth Council has been accused before of failing to properly maintain its housing stock. In past reports, the Housing Ombudsman highlighted what it called a “pattern of neglect” in the borough’s response to serious disrepair, particularly within its aging post-war estates. Such cases, the Ombudsman noted, often involved long delays, a lack of communication, and inadequate interim support — all concerns raised again in Roehampton this month.
Listed — and legally protected
Denmead House is a Grade II* listed building, which means any works affecting its structure or historic character require special consent. If, as reported, a large crack appeared in the underside of the building and repair works were undertaken, Wandsworth Council would have needed to apply for Listed Building Consent (LBC) before proceeding — especially if the repairs involved replacing original materials or altering the structure.
Internal approvals may also have been escalated due to the building’s protected status. As the building’s owner, the council has a legal duty to preserve its architectural significance. While there is no explicit law forcing constant maintenance, allowing it to fall into disrepair can trigger enforcement under the Planning (Listed Buildings and Conservation Areas) Act 1990. Importantly, unauthorised works — even repairs — are a criminal offence, regardless of whether the owner is a private landlord or a public authority.
Residents fear neglect is political
This summer, Wandsworth Council is expected to bring forward its long-delayed plans to redevelop parts of the Alton Estate. Previous proposals — including one by developer Redrow — were withdrawn in 2020. The new plan involves knocking down a number of buildings on the estate and building new flats.
But tenants living in the historic blocks believe that years of poor maintenance are not just neglect — they’re strategy.
“It feels like they’re letting the buildings fall apart on purpose,” said one resident. “If they want to knock them down, they just make them unliveable.”
The council has been criticised before for the slow pace of regeneration and the conditions on parts of the estate. In 2023, community groups warned that the council was “managing decline” rather than investing in repairs.
Now, with cracked concrete above their heads and no communication, some residents say they’ve lost trust entirely.
Putney.news continues to seek answers from Wandsworth Council and will publish any response in full when received.
