by Susan K. Weiler and Katrin Scholz-Barth

Green roofs, whether intensive or extensive, can provide a wealth of benefits on site and beyond. Delivering these benefits successfully requires professional attention to a variety of critical details. — Editor

The first common dilemma in the construction of living green roofs, and other landscapes over structure, is that, in conventional building, the execution and completion of site work are often subordinated to the completion of the building.

From the very beginning of construction of early packages through the completion of a project, the coordination of trades, protection of materials, sequence of construction, effects of seasonal climate, project costs, and time issues involved in the green roof system must be brought to the attention of the construction management entity.

Survey Data and Project Layout Control

As with all projects, proper horizontal and vertical control is important. However, because typically the tolerance in horizontal and vertical layout of landscapes over structure is quite limited, discrepancies between the survey data and the actual field conditions can lead to layout inaccuracies and poor coordination of elevations.

Discrepancies in survey data, including elevational information, horizontal data, and utility layout, can occur when a city or municipality uses one set of data and the overall survey information (aerial, USGS, etc.) uses another. Utilities may be in different locations or at different elevations or may be missing altogether, which can impact stormwater drainage construction and other systems.   >>>

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SUBSCRIPTION SAMPLE Planted roofs can provide a colorful accent, changing the building with the seasons. Photo: Kai-Henrik Barth Extra Large Image Oversized pedestal supports provide stability to accessible rooftop hardscaping, such as these large granite pavers, without impeding drainage. Photo: Olin Partnership, Ltd./ Courtesy Wiley Extra Large Image   Click on thumbnail images to view full-size pictures.