|Finished green roof. Mason bee boxes nest in the gable.|
Although installed more and more in commercial developments, green roofs are underutilized on residential structures. The benefits of a green roof are many and include: mitigating and cleaning storm water run-off; reducing the urban heat island effect; providing summer cooling and winter insulation, thus lowering energy costs; providing habitat for beneficial insects and providing noise insulation, just to name a few. Green roofs have been used by different cultures for hundreds of years, but we are just starting to understand how well they function as a viable roofing system. Being that we live in the Norwegian ghetto, having a green roof keeps up with Scandanavian tradition as these roof systems planted with turf on birch bark water-proofing were quite common in that part of the world, once upon a time.
The perception of green roofs being expensive and high maintenance is unfortunate. In reality, most green roofs require little to no maintenance. Just the occasional pulling of unwanted seedlings or top dressing every few years with compost is all that’s usually required. Like any type of garden, it’s about the soil. A low-nutrient, free-draining soil will cause much less of a weed problem than a soil rich in organic matter and nutrient levels. Dead heading is not necessary, and the use of drought tolerant plants such as succulents, eliminates the need for constant irrigation.
This roof is called an ‘extensive’ roof system, meaning that the substrate is less than 6 inches thick. ‘Intensive’ roof systems have much deeper substrates, allowing for larger shrubs, grasses and even trees. Extensive systems are lighter weight (around the weight of a tile roof) and the plant materials used most often consist of succulents which can grow well in a shallow, rocky soil. Last fall, I picked up 9 sedum tile flats for half price at a big box store.
This roof system caused Roland to exacerbate an eye-rolling habit he usually expresses around me. It started with my initial proposal of installing a green roof the minute he announced that he was going to build a garden shed, followed with, "How do I do that?"
|Installing the front drainage gravel.|
|Installing the liner.|
|The substrate mix.|
|The plant material - sedums with Hens and Chicks.|
A lot of folk who came through the tour commented on the green roof. They thought it was a great idea and looked really nice.
I proclaimed to Roland, "I think you should convert the roof on the front porch of the house into a green roof when you re-build the front porch deck."
His response? More eye rolling.