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The Sill: National Landscape Discovery Centre

Geoenvironmental, Structural, Civil
  • LocationHexham, Northumberland
  • GradingWorld Heritage Site
  • Value£14.8m
  • ClientNorthumberland National Park Authority
  • ArchitectJDDK
  • AwardsWinner - Planning Permission of the Year Award 2015

Patrick Parsons provided engineering designs for Northumberland National Park Authority’s new £14.8m state-of-the-art visitor centre.

The building features exhibitions focusing on landscape, culture and heritage, as well as several learning and event spaces, a Youth Hostel and a café and shop.

The 2,900 m2 building works with the natural contours of the site and is partially embedded in the landscape to minimize its impact on the surrounding scenery. The complex geometry of the building incorporates a sloping fully accessible grassland roof – the only one of its kind in the world – with a viewing platform providing views over the site.

The project is in an archaeologically and environmentally sensitive site and this confluence of special circumstances meant the site was one of the most challenging to develop in the whole of the North East. Patrick Parsons’ structural team used a wide palette of structural forms ranging from reinforced concrete for the free-flowing curves of the superstructure and retaining walls in the partially below ground element, steel framing in the rectilinear areas which require large open panels, load bearing masonry within the compartmental YHA and natural stone gabions to the elevations.

Our Civils team have addressed the challenges of this remote location by incorporating a suite of sustainable drainage solutions, including waste water management, rainwater harvesting and discharge of foul via a sewage treatment plant to a nearby burn at a controlled rate and at a quality acceptable to the Environment Agency (EA).

Patrick Parsons’ geonvironmental specialists tailored the requisite geoenvironmental investigation to minimise possible impact on archaeological deposits and the firm’s civil team addressed the challenges of the site’s remote location by incorporating a suite of sustainable drainage solutions.

BIM was used heavily in the production of design information by the whole design team. Clash detection exercises during the design phase significantly reduced the number of issues on site minimising potential additional costs and helping the project stay on program.


The unique design of The Sill: National Landscape Discovery Centre required experienced and high quality structural design services.

Patrick Parsons' design and approach enabled the National Park Authority to confidently progress with the installation of a publicly accessible local grass and wild flower roof to take the weight of over one metre of soil and supported drainage substrata, whatever the weather. This is the first time such a facility has been designed into a building in the UK.

Stuart Evans, Head of Corporate Services for Northumberland National Park Authority