Green Roof Structural Engineering

For retrofitting a green roof wall or facade it is important to establish early whether the installation will meet the existing structural capacity of the building or whether this will be modified to support the installation.

Green roof structural engineering.

Green roofing the term green roofs has taken on several different meanings in recent years. Incorporating gardens or other forms of green roof plantings can be an attractive alternative to traditional building construction. Proper selection of agriculturally durable materials structural engineering design and review and responsible water handling should all be considered to achieve maximum energy efficiency and perhaps leed recognition. The popularity of green roofs has risen in the united states over recent years as a result of several contributing factors.

This chapter considers the technical and engineering considerations that stakeholders need to take into account. A portion of the captured rainfall evaporates or is taken up by plants which helps reduce runoff volumes peak runoff rates and pollutant loads on development sites. Soil does not necessarily occupy the full depth of the assembly. I have a client who is looking to place a green roof on top of a proposed single story commercial building.

Currently the building is being proposed using a modular roof system. The proposed depth of the system is 5. Some roofs are finished with substantial architectural build ups such as concrete pavers or stone. With regard to green roofs the overriding issue is one of structural capacity to accommodate the additional loads.

The first conservative assumption by structural engineers is to use the full saturated weight of 110 pcf for the full depth of the green roof assembly. Being the structural engineer i need to account for the weight imposed on the roof by the system. Modern green roofs typically use lightweight engineered soils with very light drainage and insulation layers. Removing unnecessary finishes may provide sufficient capacity for a green roof of equal weight.

Green roofs lessen the environmental extremes common on conventional roofs reduce storm water runoff increase energy efficiency and enhance the urban soundscape. At sullivan engineering llc we define green roofs as those roofs that contain vegetation also known as vegetative roofs. Waterproof membranes now make it easier to design green roof systems that capture water for irrigation allow drainage support the growing medium and resist the invasion of roots.