Our Chair, Sir Derek Myers, outlines our plans for the future of the Conservatory

The Conservatory is much loved by us and by our visitors.

Not only is it lovely to look at, but it is also recognised as contributing to the setting of the Grade I listed landscape.

It has been home to several camellia shrubs for many years. These plants, when first introduced to the UK, were regarded as exotic and tender and requiring protection under glass to ensure they flowered as well as possible. As can be observed in the Gardens, camellias in London will now grow unprotected and when under glass require more care, in terms of watering, shading, pest and disease control.

The current Conservatory is not the original, which was built in 1813. The walls, floors and backsheds masonry structures are still predominantly from 1813, but the current timber glasshouse superstructure dates to the 1930s. It uses a system and design, manufactured by a company called Messenger & Company, that differs from its predecessor. Further overhauls followed in the 1950s, the 1990s and in 2008. Three lots of smaller repairs have been carried out since then.

Regular piecemeal repairs are expensive, costing tens of thousands of pounds, and are unsatisfactory as new areas of deterioration constantly arise, even when they are not a structural risk they look as though the building is unloved.

Thanks to the Culture Recovery Fund, we paid for a team of experts to explore what options exist for the future of the Conservatory. The Executive Summary of that report is reproduced below. The costs of full repair options range from £2.7m to £5.5m. The report also advises the cost of ongoing maintenance repair costs, even after these expensive improvements, will amount to tens of thousands of pounds a year. This will always be a considerable strain for our small charity. Careful and thorough consideration needs to be given to the range of options available to secure the future of the Conservatory.

The Trust has ambitious plans for extending our charitable work beyond the maintenance and conservation of the historic gardens and buildings, to ensure we can offer opportunities for learning and enhancing confidence and wellbeing for our local community.

We have commissioned initial work on the ideas for three exciting priority projects outlined in our 10-year plan thanks to a grant from the Architectural Heritage Fund. These projects seek to improve facilities for the local community and school groups, plus the creation of a brand-new cultural hub for designers and makers in our ‘back-of-house’ spaces. We intend to fundraise for and deliver these priority projects first. Find out more.

Creating a Cultural Hub and improving community and learning facilities are vital first steps for securing the future of the House and Gardens in the current economic climate. As well as providing opportunities for skills building and supporting the local economy, income generated through the Cultural Hub will provide vital income for the Trust’s work, including costs associated with the ongoing preservation of the Conservatory. As well as being the right thing to do, strengthening our community and learning programme will also help the Trust to make a stronger case for future funding. The London Borough of Hounslow’s Thriving Communities Capital Fund are funding the work to shape these proposals ready for consultation with our community groups, stakeholders and planning. We are also working with the council’s Creative Enterprise Zone (CREW) team to shape and identify funders for the Cultural Hub.

The Conservatory cannot be our first priority, given the huge sums required to give it a new long-term future. In recognition of its importance, conservation of the Conservatory will be the second phase in the Trust’s multi-phase 10-year vision. We are therefore working in partnership with the London Borough of Hounslow, who own the Conservatory, to put together a partnership project. This will allow us to progress planning for the future of the Conservatory, with a view to securing this iconic building.

In the meantime, we are committed to monitoring the condition of the Conservatory and carrying out interim repairs, with the support of London Borough of Hounslow, to ensure we can continue to use the central rotunda for weddings, events and for our visitors to access the Kitchen Garden.

Sir Derek Myers
Chair of Trustees
December 2022

Conservatory Appraisal – Executive Summary

The existing glazed structure has been examined and the extent of decay recorded against that in 2018 showing that it is progressing at an ever-increasing rate despite periodic repair.

The agencies of decay have been analysed, concluding that the extensive fungal decay of the timber structure is due to ingress of water from the outside, causing much of the structure to have high moisture content virtually all the time. Underlying deficiencies in the detailing, construction and materials specification make the structure fundamentally vulnerable and decay is so extensive as to make comprehensive repair unviable. All that can be achieved with the existing fabric is the short-term management of defects to maintain structural integrity, and that can only be for a few years.

Options for the replacement of the glazed structures have been explored, and seven strategic approaches have been described in detail and costed. These are:

• Retention and repair of existing fabric (not considered viable)
• Comprehensive repairs and detailing improvements, amounting to reconstruction to new bespoke details
• Reconstruction to Messenger & Company system by specialist manufacturer
• Reconstruction with bespoke joinery and aluminium roof glazing
• Reconstruction in full aluminium system with similar appearance
• Reconstruction as open primary frame without glazing
• Permanent demolition and weathering of the masonry structures

All options have been considered against practical, heritage and cost criteria, both for capital expenditure and extended ongoing maintenance. The process and challenges of consents have also been explored and it is considered that all the reconstruction options are worthy of consideration. Early consultations with heritage stakeholders are essential before the preferred option is selected.

It is concluded that:

• The retention and repair of the existing structure is not viable
• The option to repair and improve details and the similar option with aluminium roof glazing is dependent on bespoke details and on-site construction quality which increases the risk of repeated failure.
• The two factory-finished options of timber Messenger & Company system and aluminium look-alike system bring the substantial advantages of tested long-term system design development and tightly controlled factory construction. These are considered the two preferable options, with different merits in the long and short term.
• The various options for partial or total demolition does not achieve the primary objective to conserve the historic building and should only be considered as fallback positions if reconstruction should prove to be unachievable.

Recent experience has starkly illuminated the need for ongoing and rigorous maintenance. The practicalities of maintenance are considered for the various options, concluding that a regime for maintenance should be in place from the outset, and that consideration of the access infrastructure for doing so should be integral to the design.

(Note we are not releasing the full report in case it compromises our commercial position if or when we engage with contractors for future works.)

FAQs

Who is responsible for the Chiswick House Conservatory?

Chiswick House & Gardens Trust operates the Conservatory on a day-to-day basis and is responsible for maintenance. Because of the significant deterioration of the building, the Trust together with London Borough of Hounslow (who own the grounds), are putting together a partnership project to fund a major overhaul of this important historic building.

Why are the wings of the Conservatory currently closed?

The building requires specialist conservation repairs due to its age and historic design. The extent of these repairs is currently being planned. In the meantime, repairs to the Rotunda have been carried out so that this can remain open for visitors and events.

Why have the repairs carried out in 2010 not lasted?

The building is a one-off design and previous maintenance repairs have not proved a permanent solution to protecting the building from the weathering effects of wind and rain, in particular the impact of climate change.  Knowledge of the bespoke system, designed by Messenger & Company, did not exist when the repairs were last carried out. This system is now back in production.

Are the camellia shrubs safe?

The camellia is a hardy plant and prefers to be outside. It gets too hot under glass and camellias need regular watering, to be kept shaded (by pulling the blinds down) and free of pests and disease. To safeguard the camellias, we have taken cuttings and we also have plantings of duplicates outside where they are thriving without regular care other than seasonal pruning.

How long will it take to repair the building?

This is not currently known.

When will you know?

The Trust and the Council are taking expert advice from a range of specialists to find the best solution. Once there is a clearer view then there will be an update on the proposals and the funding needed to carry out the works. In the meantime, we are carrying out emergency repairs to keep the building safe for visitors.