Having opened its doors in June 1993, Tate St Ives recently underwent a major transformation, extending the original building to better accommodate the quarter of a million visitors that can now pass through the gallery every year. The work consisted of an extensive refurbishment of the original gallery, as well as a 1,320m² extension that added a brand-new gallery, education spaces and offices.

To extend the original Tate St Ives, workers dug 15m into the cliff side surrounding the original building. Jamie Fobert Architects designed the extension with an expansive green roof, with the vision of merging the new structure with its neighbouring landscape.

Jamie Fobert, Director at Jamie Fobert Architects said: "The coastal setting and vernacular of St Ives have both influenced my approach to this work. Entirely excavated into the hillside, the new gallery extends, in a continuous journey, the existing gallery sequence. On its roof, weaving between six large light chambers, stairs and costal planting create a new public space for the town."

In order to complement the aesthetics of the surrounding scenery, the green roof was designed to include a number of mounds and hills ranging from 450cm to 2m in height. Having worked closely with the architects from the early stages of the project, Eco Green Roofs was able to assist with assessing the chosen method used to construct the mounds.

The original specification suggested that the substrate be moulded to insulated board, however it was predicted that the substrate could slip away from the board, therefore failing to create the desired look. It was decided that a web structure be used to hold the substrate in place and create the raised areas of the roof.

Keith Hills, Managing Director at Eco Green Roofs, explains more about the project: "In the initial design stages we noticed the potential for excess water, and subsequently the substrate itself, to spill off the roof and run down the exterior walls of the gallery.

"To protect the aesthetics of the project, we specified a unique drainage pipe that is perforated and wrapped in a mesh fleece before being installed. This stops any substrate from entering into the pipe, but still allows excess water to be captured and transported off the roof. As the water is contained within the pipe, the exterior of Tate St Ives is protected from damage and the overall aesthetic is maintained."

Designed and installed by Eco Green Roofs, the bespoke green roof system features a pathway running from the new structure, right to the top of the cliff, and down to the beach below. The architect's design of a green roof that would be in-keeping with the surrounding area was further achieved by selecting coastal plants native to the area. In order for these plants to thrive Eco Green Roofs designed a bespoke, scientifically engineered substrate, unique to the Tate St Ives project, to support the coastal vegetation. A number of these plants were 'contract grown' over a year in advance of them being transported to the green roof, to assist with the colonisation process.

Limited access posed a huge challenge during the construction stage. The narrow roads leading to the construction area made delivering and storing materials incredibly difficult. A 'Just In Time' approach to deliveries was required, with the EGR team having materials delivered to a local rugby club car park, where they were held temporarily until they were moved to site one by one as needed. A social housing block for those living with critical illnesses was also located just one metre away from areas of the site - considerate planning was required to ensure that materials could be moved safely and efficiently.

Jonathan Morton Head of Business and Operations at Tate St Ives said: "The refurbishment and extension has enabled us to increase our visitor capacity and create a stunning outdoor space to enjoy. The Eco Green Roofs team worked proactively to ensure that the green roof would be in-keeping with the surrounding landscape. The inclusion of coastal plants native to the local area has really helped to merge the new Tate St Ives into the existing cliffside and coastal landscape – which was a key design criterion for the new gallery."

Keith Mills of Eco Green Roofs concluded: "This project was particularly challenging – not only did we have to ensure that the architect's vision could be achieved, we also had to contend with site access issues and tight time schedules. Our team worked tirelessly to create a space that would blend in with the surrounding landscape and we are incredibly proud of the end result. We hope that the local community and tourists alike will enjoy both the indoor gallery and green outdoor spaces that Tate St Ives now offers."

To view and download the full case study that includes coastal aerial drone footage visit: www.egr.co.uk/case-studies