Donald Insall Associates completes a five-year overhaul of the world’s largest Victorian glasshouse


Gareth Gardner

Donald Insall Associates has completed the five-year renovation of Decimus Burton’s magnificent Temperate House at the Royal Botanic Gardens, Kew. Design and construction of the world’s largest Victorian glasshouse began in 1859 and was completed in 1899, 18 years after Burton’s death. Its series of five linked pavilions stands on a raised earth mound, and contains a collection of 10,000 plants from around the world. The renovation project provides a better environment for the plant specimens, allowing greater air flow and optimising natural light.


The building was stripped of its living botanical collection, save for nine trees which were deemed too horticulturally significant to risk moving. Paint analysis revealed that early decorative schemes had stone-coloured walls with pale blue and off-white decoration on the structure. The later blocks originally had a dark green colour scheme. The modern titanium dioxide white decorative scheme first applied in the 1950s has been replaced with polychromatic stone colours, picking out architectural details and high-level sculpture, following the paint analysis research.


Cleaning the structure with ultra-high-pressure water and crushed garnet blasting revealed the original casting marks and metalworkers’ stamps. New stamps indicate the use of new materials including lead work, replacement castings to the snow guards and finial details. Stamps were omitted from the new glazing to maintain the purity of light transmission and reflection.

To facilitate the re-painting and re-glazing, 69,151 individual components were dismantled and stored, with digital records kept of their original positions. “In retrospect, dismantling the building was the easy part”, says the architect. “Reinstatement created many challenges especially when working in contemporary elements into the structure whilst taking into account the aged junctions and weathering details”.


Landscaping, both internally and in the approach to the building, has been improved, providing inclusive access to all visitors. The visitor experience has also been enhanced through interpretation facilities. “The restoration of the Temperate House has been a complex and immensely rewarding project, recalibrating contemporary understanding of Victorian architecture and the development of past innovations”, says Aimée Felton, lead architect on the project: New glazing, mechanical ventilation systems, path and bedding arrangements all took their founding principles from Decimus Burton’s own drawings, held within Kew’s archives. The time it will take for the newly propagated plants to reach maturity will offer visitors a full and unobstructed view of the incredible metal skeleton in all its glory: a cutting-edge sanctuary for plants.”

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Donald Insall Associates
Royal Botanic Gardens Kew
Project manager
Turner & Townsend
Structural engineer
M&E engineer
Hoare Lea
Land Use Consultants
Compass Archaeology
Sculpture restoration
Taylor Pearce