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Macallan Distillery Extension

Despite poor weather, isolated location, and a large, undulating rooftop, Sky Garden managed to create Europe’s largest wildflower roof. It won the Green Roof category of the Roofing Awards 2017

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Set in the heart of the Scottish Highlands, near the River Spey, the Macallan Distillery has been producing whiskey since 1824 at the beautiful 18th century Easter Elchies House. The client wanted a modern facility and visitor centre that would not only help them to meet growing demand for their single malt whisky but would complement the setting.

The architect Rogers Stirk Harbour + Partners, therefore designed a modular building with an undulating green roof to help the building blend within the surrounding countryside. Composed of a timber grid-structure, the 12,000sqm double-curved roof, which features five mounds to accommodate the distillery’s five production cells, is one of the largest wildflower roofs in Europe.

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At a glance

  • Client: Macallan Distillery
  • Architect: Rogers Stirk Harbour + Partners
  • Landscape Architect: Gillespies
  • Main Contractor: Robertson Construction Group
  • Roofing Contractors: Blue Sky, with Topack
  • Building Type: Industrial
  • Location: Aberlour, Scotland
  • Completion: 2017
  • Roof Type: Green Roof
  • Finish: Sky Garden Wildflower Blanket Green Roof System
  • Underlay: Resitrix
  • Battens: WIEHAG glulam timber

Complexity

The irregular shape and scale of the roof made this a highly complex project that tested the knowledge and experience of both Sky Garden and Topak Ltd, which installed the expression channels. In order to hold the channels in place and maintain their shape, the Sky Garden installers had to fill the channels with washed river stone pebbles, the narrow width of the channels forcing them to use 25kg bags rather than bulk bags. The roof was broken down into sections so that once the river stone was installed in one area the green roof, components could be installed one square at a time between the channels.

Careful planning was needed to install the green roof system on the five mounds, which covered the production cells, in order to prevent it from sliding. The mounds were broken into squares, based on their pitch, with soil retention layer incorporated into the system for areas between 12 and 19 degrees. This was installed above the drainage and filtration layers and then filled with the substrate.

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The challenges

Poor weather presented the biggest challenge for Sky Garden. The installation was scheduled for the end of the year but with Macallan Distillery located in the north-east of Scotland, this meant the team having to work in temperatures as low as -12°C and caused a number of issues.  

The heavy frost and icy conditions on the roof, especially on the pitched mounds, were impossible to work on until they thawed out, made worse by large portions of the roof was not getting any sunlight until late in the day.

Meanwhile, the wildflower blanket rolls and bags of substrate were often frozen solid and so could not be installed for long periods of time. Labour and site management was therefore critical in keeping the project on track in terms of time and budget.

Timing was a challenge throughout, with blanket sowing beginning in April 2016 that gave Sky Garden only a single growing season to get the wildflower blanket sufficiently advanced for delivery to Scotland.

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Workmanship

High levels of workmanship were upheld by all project contractors. The latest in 3D modelling technology was used for the entire building design, which was tailored to hold the green roof system.

The expression channels across the roof were specifically designed to retain the green roof system at the steepest pitches on the five mounds, while the wildflower blanket was grown specifically for the project by Sky Garden’s own experienced growers.

Meetings with the architects and detailed research of the surrounding area, enabled Sky Garden to engineer a bespoke seed mix that would replicate the surrounding landscape. The mix was sown at Sky Garden’s nursery and production site in the heart of the Cotswolds and carefully monitored throughout the growing phase, with monthly reports and quality assurance testing. Only the highest quality blanket was delivered to Scotland, with further checks undertaken once the vegetation reached site.

Regular quality checks were carried out throughout the project to ensure the high standards of workmanship. As each layer of the green roof system was installed, checks would be made before the next component was placed. Coverage of fleeces and drainage layers, depth of substrate and quality of wildflower blanket were just some of the criteria checked throughout the project. 

Sky Garden says

We are proud to be part of this outstanding project which has succeeded in integrating a substantial and unique building into the sensitive Scottish topography. The green roof is the essence of this project. By some margin this is the largest known wildflower roof in Europe and given the roof design, it is certainly the most innovative and challenging green roof we have ever installed.

About Sky Garden

Sky Garden is the UK’s leading independent supplier and installer of green roof products. Our expertise encompasses consultation, development, installation and maintenance of all styles of green roofs and surfaces. As well as being committed to protecting and enhancing the environment we are also dedicated to providing great service and innovation in all areas of our business.

www.sky-garden.co.uk