Chiswick House Conservatory at Risk of Collapse

£4.5 million might be needed to repair historic building

The conservatory at Chiswick House. Picture Chiswick House and Gardens Trust

December 13, 2022

A report has found that the conservatory at Chiswick House is no longer safe for public use and is at risk of collapse.

Rotting and weakened timber at the historic site could cost the council £4.5 million to repair.

The conservatory dates back to 1933 and despite three separate repair projects, the structure is quickly deteriorating, according to the report submitted to Hounslow Council.

Emergency repairs, due to be completed in January 2023, are being carried out to stop the building from collapsing but this is only a short-term fix. Over the last ten years, Chiswick House and Gardens Trust has already spent £98,000 on repairs, with the emergency work expected to cost the council a further £60,000.

Most of the damage has come from the “extensive fungal decay” of the timber structure due to dampness that has caused rot. Plus, repairs and alterations in the 1950s, 1990s and 2008 did not match the “sophistication and technical specification” of the original build, which in turn failed to protect the historic site.

The report says, “The structure is now fundamentally weakened and most of the building is not safe for public use and has been closed off. Without emergency repairs, the building will deteriorate faster and cost more money to renovate and risk a collapse for which the Council would be responsible as the owner.”

The report continues, “Reactive emergency repairs are only a short-term mitigation and that failing to bring forward a scheme for full renovation and structural in a timely manner is likely to increase the risk of building collapse or a major accident.”

It is estimated that a full renovation will cost approximately £4.5 million. The full details of costs and options will be further developed, with a full report expected to be presented to Hounslow Council next Autumn.

The conservatory at Chiswick House. Picture Chiswick House and Gardens Trust

To make the Grade I listed structure more resilient, renovation works will need to be energy efficient. Plus, renovations will need to include modern facilities that can support multiple uses such as new planting, weddings, private events and a tea house.

A fundraising strategy, to be developed over the next few months, will decide how much the council needs to contribute to the estimated £4.5 million repair works. Hounslow Council’s Cabinet is expected to initially approve a budget of £423,000 to fund the initial development phase.

A full report on the renovations needed will be submitted to Hounslow Council in September 2023. If approved, it is expected a planning application will be drawn up by January 2024.

Megan Stanley - Local Democracy Reporter