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.   >>>

This article is excerpted from Green Roof Systems by Susan K. Weiler and Katrin Scholz-Barth, copyright © 2009, with permission of the publisher, John Wiley & Sons.