Can Dirt Insulate My Roof?

Layers

• Soil is just one layer necessary to create a green roof. Soil is the top layer into which plants, shrubs and grass are planted. Without the flora to bind it, the soil would wash away in heavy rain. Underneath the soil is a drainage layer. This prevents the soil from becoming waterlogged. It is often comprised of crushed brick. Beneath this will be an insulation layer, followed by a waterproof plastic membrane to stop the water from coming into contact with the roof. Some green roofs also install a water-retaining layer above the membrane if the plants require a lot of water.

Benefits

• A green roof is effective at providing heat insulation, keeping the building warm during the winter and cool during summer. This reduces energy bills. It also provides insulation against sound. Green-The-World.net reports that a 12 centimeters layer of soil can result in noise reduction of up to 40 decibels. The dirt holds rainwater, which eases pressure on the building’s drainage system. A green roof will create a natural environment and attract birds and insects.

Downside

• Green roofs are expensive to install, given the number of materials required. They can put extra strain on the structure of the building, particularly after heavy rain when the soil is saturated. They may require maintenance, such as weeding out invasive species. Plants may get into the drainage system. Also, not all roofs are suitable for supporting a soil-based insulation system.

Roof

• The roof must not slope by more than 35 degrees. Green roofs are ideally suited for installation on flat surfaces. The roof must also be sufficiently strong to bear the weight of the soil and attendant layers.