Kew Gardens – Tor Coatings

Temperate House Restoration - Kew Gardens

1078 linear metres

Elastaseal Gutter System

Donald Insall Associates

Full Metal Jacket

The refurbishment of an historic glasshouse at the world-famous Kew Gardens in London, England. The spectacular, Grade I listed, Temperate House is the world’s largest Victorian glasshouse. It was built between 1859 and 1899 and is home to over 10,000 plants, including some of the rarest species found in temperate regions around the world. It attracts over one million visitors annually. By 2012 the glass and metal structure was in a state of disrepair, in fact it was predicted that the structure would fall down if it wasn’t saved. This led to a major restoration project costing £41m. During the five-year refurbishment the 52,500ft2 building was closed to the public and shrouded in an enormous protective tent; large enough to cover three Boeing 747 planes. The Temperate House was designed by architect Decimus Burton and took 40 years to complete, for the refurbishment Donald Insall Associates were appointed. The Temperate House was re-opened by the famous English broadcaster and naturalist Sir David Attenborough on May 3rd 2018.

Bringing the building back to its former glory involved painstaking dismantling, restoration and reinstallation of unique components, including the original cast iron gutters that extended around the perimeter of the multi-tiered roof structure. Sections of the original cast iron guttering were taken from Kew to a shot blasting facility, where existing layers of paint were removed, leaving a bare metal surface. This was then primed with an anti corrosive, adhesion promoting primer as the first layer of protection. The sections were then treated with the embedment layer before being transported back to Kew. Once back in situ, the gutter joints were treated with a localised reinforcement layer before the topcoats were applied. Based on a high solids formula, with built-in fiberglass reinforcement, the heavy-duty system delivers incredible tensile strength and resistance to water. It includes proprietary components, to encapsulate bolt heads and bridge joints, and ensure a seamless waterproof finish. The polyurethane liquid system selected has a guaranteed minimum life expectancy of 20 years, which can be extended by simply re-coating – a feature that appealed greatly to the client.

The challenges on this project were numerous, firstly, the gutters were in such poor condition that over 30% of them had to be removed from the structure to allow sections to be replaced and others to be shot blasted and repaired. The client liked the idea of being able to install layers of the coating system offsite as this saved time on the complicated structure. The intricate gutter rib strengthening details lent themselves perfectly to a liquid applied solution where we could treat all of these areas easily with a fully bonded system. Whilst this wasn’t the largest project in 2018, it has been one of the most challenging. Working on a structure where corrosion had taken a firm hold was at times a delicate and dangerous task. The client was very keen on adding corrosion protection layer in the cast iron sections so we chose our epoxy surface tolerant metal primer which imparts high adhesion strength and is enriched with zinc and micaceous iron oxide elements to provide a high quality corrosion resistant layer for the cast iron substrates. This primer was also used in the lead lined in situ gutters.
We then applied the full 20 year waterproofing system which has been exhaustively tested for environments where ponded water is prevalent and demonstrates highly effective resistance in these areas. The clients were also keen to use a system that can be easily maintained in the future by simply cleaning and adding a further topcoat.

To facilitate the re-coating and re-glazing, 69,151 individual components were dismantled and stored, with digital records kept of their original positions and 5280 litres of protective coatings were used in the overall project.