System × Plants × Operations
Cause of Rooftop Greening Failure (3)
— Designing by Separating “System × Plants × Operations”
When rooftop greening is explained using only a single element,
certain critical assumptions inevitably remain unseen.
There are many issues in rooftop greening that can only be properly understood
when systems, plants, and operations are viewed in relation to one another.
What “System” Means in This Context
In this article, the term “system” does not refer merely to a product or a construction method.
It refers to the entire framework required for rooftop greening to function, including:
・Layer composition
・The approach to soil and growing media
・Drainage design
・Fixing and anchoring methods
・Ease of renewal, replacement, and repair
The Problem with Treating Elements Separately
A common pattern seen in rooftop greening failures is a design approach that treats
systems, plants, and operations as separate and independent considerations.
For example:
・The system is selected first, often based on existing solutions
・Plant selection is considered afterward
・Maintenance and operation are addressed only after handover
With this kind of fragmented design process, installations may appear acceptable immediately after completion.
However, as time passes, problems gradually begin to surface.
Rooftop Greening Is a Multiplicative System
Rooftop greening functions as a system in which:
System × Plants × Operations
must work together as a multiplicative relationship.
If even one of these elements fails to align, the result is not always a simple outcome such as “plants dying.”
Instead, failure often appears in forms such as:
・“The greening does not function as intended,”
・“Vegetation does not spread or establish sufficient coverage.”
Why These Failures Are Difficult to Resolve
Failures of this type have a characteristic feature:
responsibility cannot be clearly attributed to any single party—whether system design, plant selection, or maintenance.
As a result, issues tend to be deferred rather than resolved.
The key question, therefore, is whether plant characteristics and operational assumptions are considered as an integrated whole at the stage when the system itself is selected.
This perspective plays a decisive role in determining the long-term stability of rooftop greening.
Back to Site Top▶
The Structure Behind Sound Judgment▶
Structures That Lead to Failure▶
