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What We Did
The works comprised of an extension to the Cairngorm National Parks Association Headquarters in the Square Grantown on Spey. The building is a traditional stone built with a pitched slated roof. The Architects wanted something to blend in without altering the overall appearance too much. The building stands in the Square Grantown on Spey a very popular place in summer and winter and is surrounded by Victorian hotels and guest houses, the extension had to be very sympathetic to the surroundings. The flat roof comprised of a terraced area where staff could enjoy the outdoors looking on to a green roof laid with colourful heathers. The material chosen for the project was the Alwitra single-ply membrane and green roof system, with paving slabs on adjustable pedestals to the terraced area. ICB the Alwitra manufacturer carried out a condensation risk analysis for the proposed system and was approved by the local planning authority. The roof comprised of the following.The Terraced Area
The timber deck was primed then covered with Eva Vap self-adhesive vapour control layer. Tapered insulation was laid adhered to the VCL then primed. Alwitra VSK self-adhesive single ply membrane then covered the insulation and completed the waterproofing. A protective fleece was then introduced prior to the adjustable pedestals and stone paviers been fitted.
The Green Roof Area
The roof was laid in the same fashion as above, up to the VSK membrane, we then fitted a protection fleece, reservoir drainage boards, a filter fleece, then laid 200mm of soil growing medium. The area was then planted with indigenous heathers arranged in groups of five per m2 in a random system. The border was made with gravel retaining boards and infilled with stonewashed pebbles. The heathers were chosen for their hardiness and stunning colours, Deschampsai Cespitosa, Briza Media, Carex Evergold, Erica Vulgaris, Heurchers Binoche, Blue Rider Lavender, Potentilla Verna.
The Result: A Living Roof That Belongs in the Cairngorms
From The Square, the new extension to the Cairngorms National Park Authority’s headquarters sits comfortably beside the original stone building. Its roof looks less like a flat roof and more like a piece of the surrounding landscape, planted with native heathers, grasses and wildflowers that change with the seasons.
Underneath the planting, the Alwitra VSK single-ply membrane and tapered insulation keep the building watertight and well drained through a Highland winter. A paved terrace on adjustable pedestals gives staff a usable outdoor space without compromising the waterproofing below.
Most of the work that made this possible is now out of sight: ICB’s condensation risk analysis, the layered drainage and filter build-up, and 200mm of growing medium laid to support the planting for years to come.
The industry noticed too. The project won the Green Roofing Award at the 2019 NFRC UK Roofing Awards.
