Over at the museum’s research and collections facility in Gatineau, Quebec, the roof that protects our extensive book collection and keeps the rain and snow out of our labs has just gotten a green facelift. Last year, when planning for the replacement of our 16-year-old roof, we decided to replace part of this (very) large area with a green roof.

Overhead view of men working on a partially finished section of the roof.
The modular design of the roof allowed for the job to be completed within a few days. Image: Paul Sokoloff © Canadian Museum of Nature

Other than looking good in aerial and satellite photos, a green roof has several advantages, especially when the protection of a large number of irreplaceable collections is a concern. Compared to a conventional roof, our green areas will last longer and provide better insulation during summer and winter, and the greenery doesn’t absorb ambient heat. Also, in keeping with our mission to reduce the museum’s impact on the environment, these green roofs capture rainwater and sequester carbon dioxide.

A crane in front of the building.
A large crane solves the logistical challenge of moving large trays of live plants onto the roof, especially to areas in the middle of the building. Image: Paul Sokoloff © Canadian Museum of Nature
A rack of plant trays.
Trays of stonecrop (Sedum) waiting to be lifted onto the roof. Image: Paul Sokoloff © Canadian Museum of Nature

One of the primary concerns of any facilities work at the building is conservation: how can we minimize impact to the collections and ensure their preservation. To do this, we need to make sure insects, live plants, pests and water—anything that is potentially damaging to the collections—stays out. The green roof not only excels at trapping water, but is also weed resistant; the substrate that the roof contains is inhospitable to most weeds, and is well suited to the succulent stonecrop species that make up the “green” in our green roof. Fewer weeds mean fewer opportunities for pests to creep in.

Close-up of plants in the ground.
The stonecrop (Sedum) varieties were selected for their hardiness and longevity, and will eventually fill in the roof with a succulent lawn. Image: Paul Sokoloff © Canadian Museum of Nature

While many green roofs have traditionally used grasses and other densely growing plant species, our roof, and increasingly others, is made of up exclusively of Sedum species. This genus in the family Crassulaceae has several adaptations that are useful for a green roof. Stonecrop fans and gardeners alike know that these species quickly cover the ground they are planted on, supressing weeds in the process.

Also, because these plants are succulent, the plants retain water during drought. Their metabolism (crassulacean acid metabolism, or CAM), allows energy production to occur in even the driest conditions. Finally, many perennial Sedum species are cold adapted, allowing them to survive into autumn—a necessity for a building in Gatineau.

One photo showing an area of roof with stones and other material used in preparing for the green roof, and another photo showing the plants and soil of the green roof, with a perimeter of stones.
Before and after the installation of the green roof. Images: Paul Sokoloff © Canadian Museum of Nature

We are very proud of this environmentally friendly addition to our research and collections facility. Portions of it can be seen from inside the building, and we’re looking forward to seeing how it fills out in the coming months. Next time you are flying over Gatineau, have a look down and see if you can spot our greener building.