Project Description
Raithwaite Hall is a 5 star, 45 bed boutique hotel set in 85 acres of wooded valleys within the North Yorkshire Moors National Park. The hotel offers terraced views of the landscape and across the Whitby coastline. A new extension was designed that is built against the hillside with stepped landscaped areas around the new building and an intensive green roof terrace to help blend the structure in with the surrounding gardens.
The Challenge
The intensive green roof terrace is installed directly above a new function and dining room and required a specialised design to accommodate the additional loading and provide the necessary drainage for the turf lawn.
The Solution
By utilising a multi-purpose geocomposite roof drainage board, the green roof system could be achieved to meet the project specific requirements. The ABG Deckdrain 2540S-NW20XUV product offers a lightweight option that delivers the equivalent drainage capacity of 300mm of drainage stone in a 25mm layer that weighs over a 100 times less per square metre. The lightweight drainage layer is supplied in rolls and is fast to install and move into position. The Deckdrain layer includes an integrated filter geotextile bonded to the top of the cuspated core. This prevents the growing media layer from intruding into the drainage void and filters the soil to prevent clogging. The Deckdrain is made from a high strength HDPE core that supports the 200mm deep layer of growing media required for the intensive green roof installation with deeper root systems.
The underside of the product is impermeable and provides additional protection to the liquid waterproofing membrane. A green roof surface finish further helps to prolong the lifespan of the waterproofing layer and prevent UV degradation. The large grassed area on the podium also reduces surface water run-off and the grass is protected against waterlogging via the efficient drainage board layer. The shallow drainage build-up required also reduces the height of the steps onto the terrace and the associated cost of stone flags. The completed installation encompasses a 20mm Roofdrain drainage & reservoir board to support a secondary smaller sedum roof area, as well as Deckdrain layers installed for structural drainage to the surfaces around the patio slab and retaining wall areas.
The ABG Service
ABG provided a full green roof project design, installation and maintenance service for the project.