Projects In Place and Houston Landscapes produce a video of the VanDusen Gardens Green Roof Installation

Posted on: November 17th, 2011 by Heather

I love it when two worlds collide…

Here at Projects in Place we try to teach people about the technologies that build greener neighborhoods. But as an (intern) Landscape Architect at Sharp + Diamond Inc., I have spent the better part of two years working with Cornelia Oberlander and Perkins + Will Canada on the landscape and green roof design for the VanDusen Gardens Visitor Centre.

A few months ago I was speaking to some students who help out at Projects In Place, and we hit upon the idea of doing a time-lapse movie of the green roof installation.

Below is a link to the time lapse movie. Hopefully this will provide a bit of insight into the application of green roof technology and a bit more information on the Visitor’s Centre – one of the most unique buildings you will find anywhere – right here in Vancouver.

Enjoy.

A special thanks go out to Ledcor Construction, Perkins + Will Canada, the Vancouver Parks Board and the VanDusen Garden for allowing us to undertake this project – and a huge thank you to Houston Landscape who spent hours moving our camera around, changing batteries and memory cards and generally ensuring that the movie was a success.

Bryce Gauthier
The Projects In Place Society.

 

Goals and Objectives
The new Visitor’s Center at Vancouver’s VanDusen Botanical Garden forges a unique relationship between architecture and ecology. Together, Sharp & Diamond Landscape Architecture Inc with Cornelia Hahn Oberlander, and Busby Perkins + Will Architects, have created a landmark facility to engage the public and celebrate nature in the city. The Visitor Centre is pursuing certification under the Living Building Challenge, the most advanced measurement of sustainability possible in the built environment. The integrated and collaborative design team followed four overarching objectives:

1. Education: Communicate the importance of plant conservation and biodiversity;

2. Demonstration: Provide a living example of what it means to be a botanical garden in a modern society;

3. Performance: To foster a relationship between building and ecological systems; and

4. Identity: To celebrate the concept of nature in the city.

Design Approach
Unlike a conventional botanical garden, the Visitor’s Center landscape is designed to function as it would in nature, displaying seasonal change that can be sometimes arresting, sometimes beautiful, but always interesting. The varying spaces around the Visitor’s Centre form the Cascadia Garden – a series of distinct ecological zones ranging from wetland to woodland to Garry Oak meadow. Each zone has been carefully designed and planted using only native plants that flourished when Captain George Vancouver’s Botanist, Archibald Menzies first began cataloguing this diverse region[2].

The gently sloping site was carefully re-graded to preserve the many significant trees in the garden’s collection and to facilitate a system of wetlands, rain gardens and streams that allow rainwater to infiltrate naturally. A series of plazas follow the terrain, leading people gently to the building while framing views to larger landscape. Every bench, structure, stone, plant has been locally sourced, re-used and where possible from materials found on site.

Designed to be one with nature, the VanDusen Botanical Garden Visitor Centre creates a harmonious balance between architecture and landscape. Inspired by the organic forms of a native orchid (Habenaria menziesii orbiculata[1]), the building has been organized into ‘petals’ of undulating green roof along ‘stems’ of rammed earth. These petals and stems are connected by a vegetated land ramp that connects the roof to the ground plane. Much of the roof is vegetated fescues and native bulbs to mimic a meadow.

The team was unanimous that the building and roof must appear seamless and appear to grow out of the site. Seventy-five percent of the significant trees, many of them towering Douglas Firs, were retained to enhance this experience. Large Chestnut and Walnut trees within the sloping fescue meadow create a shady wildlife corridor and habitat for butterflies, small mammals, and birdlife ultimately linking the site to the building. The living roof is designed to reflect the Pacific Northwest Coastal grassland community including over twenty species of plants, bulbs, and grasses (totaling 25,000).

The Green Roof
The roof itself is shaped and divided like the petals of a flower. These unique undulating-shaped roof planes simulate rolls and hummocks with gentle slopes ranging from 5-20%. Undulating topography create multiple drainage challenges within the individual roof petals connecting to the perimeter scuppers. The multiple low points and highpoints, varying depths of growing medium and solar orientation create planting and drainage variation. Roof garden runoff will be directed to perimeter scuppers and then to the existing stream stormwater system, enhanced infiltration beds, wetland and rain gardens.

Planting habitat design solutions include: Carex in the deeper soil valleys and depressions; fescue mix with Lilies, Onion, and Camas, at mid elevations, and sedums along exposed and steep 30% grades or within the thinner dry growing media profiles. Permanent irrigation will not be used. A specialized contractor maintenance program has been developed to give the plant material a solid chance for survival.

The membrane is a two-ply SBS with a leak detection system beneath the protection board and roof membrane, and a root barrier cap sheet in addition to the drainage mat. Growing media is performance based on criteria within our specification. Roof maintenance anchors are incorporated into individual petals. As per the Living Building Challenge Red List, galvanized material and PVC products are prohibited; materials must meet distance-based criteria.

Youtube link to the video: VanDusen Timelapse Vid

[1] Source in Karl Blossfeldt “The Alphabet of Plants”, published by Schirmer/Mosel, 2007 (originally published in 1928).

[2] Source in Clive L. Justice, “Mr. Menzies’ Garden Legacy, Plant Collecting on The West Coast”, Cavendish Books, Vancouver, BC, 2000.