Detention + Retention = True Stormwater Management

extensive green roof over parking garage in Flushing, Queens, New York with rectangles of Sedum vegetation and synthetic turf
green roof with Sedums and stripe of taller perennials in middle for greater species diversity
extensive green roof with Sedum mat blanket at glass curtain wall and treeline in Washington State

Purple-Roof is a green roof concept (with a funny name) that optimizes stormwater retention and is pioneering detention in vegetated and non-vegetated roof coverings.

  • Retention
  • Improved Plant Health
  • Lightweight
  • High Retention
  • Improved Plant Health
  • Lightweight
  • High Retention
  • Detention
  • Flat or Low-Slope Roofs
  • Improved Plant Health
  • Active Flow Control
  • High Retention
  • Detention
  • Flat Roofs

The Purple-Roof Concept createsstormwater detentionviafriction.

Purple-Roof is a specification, not a product.

Purple-Roof profile showing (from top-to-bottom) vegetation, engineered soil media, needled mineral wool water retention layer, optional honeycomb detention reservoir, and detention layer

How Does the Purple-Roof Concept Work?

Detention is "flattening the curve" of stormwater management. A detention roof, such as Purple-Roof or a Blue-Green-Roof provides rooftop detention. Notice how this is different from stormwater retention, which only works when antecedent conditions are relatively dry.

The video above explains Purple-Roof hydrology, comparing the Purple-Roof Concept, the Sponge-Roof concept, and the traditional green roof concept, starting from a dry condition, and in repeat rain events.

Why Use the Purple-Roof Concept?

The greatest benefit of the Purple-Roof Concept is its ability to function as a full-fledged stormwater management tool, potentially replacing ponds and tanks. The video above shows a practical example of this value proposition.

How To Incorporate the Purple-Roof Concept?

Where To Get Purple-Roof?

Click the map to see which companies offer Purple-Roof-compliant green roof assemblies in your area. Or contact us for more information.

More Reasons to Use the Purple-Roof Concept

Science. Resilience. Detention.

The Purple-Roof concept is scientifically developed for resilience by balancing vegetation, soil, retention, and drainage.

Purple-Roof combines this balance with the exclusive ability to truly detain a storm. Every time.

Read more.

The Purple-Roof concept is scientifically developed for resilience by balancing vegetation, soil, retention, and drainage.

Purple-Roof combines this balance with the exclusive ability to truly detain a storm. Every time.

Read more.
Need more reasons to use Purple-Roof?
Stormwater Detention

The Purple-Roof concept is pioneering detention in green roofs!

Purple-Roof profiles delay runoff and reduce peak runoff intensity to comply with stormwater detention requirements for design storms.

go to Purple-Roof detention page
Proven Performance

The Purple-Roof concept was born from 20 years of worldwide experience and exhaustive green roof research.

We research before we make claims, and we back up our claims with scientific evidence.

check out some projects implementing the Sponge-Roof and Purple-Roof concepts
Non-Proprietary Performance Specification

The Purple-Roof concept is a non-proprietary specification , not a product!

Purple-Roof projects can be competitively bid without breaking spec.

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Climate-Adapted

Green roofs should not be one-size-fits-all.

The Purple-Roof concept includes be designing and specifying appropriate to a project's climate

Contact us to adapt Purple-Roof to fit your climate.

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Sustainability

The Purple-Roof concepts includes natural materials, contains no harmful chemicals such as Formaldehyde.

Purple-Roof focuses on soil ecology following principles of nature to minimize the need for fertilizer, plant replacement, and weeding.

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Return on Investment

We believe the owner should see a return on investment of a green roof, beyond merely meeting regulatory requirements.

Core to the Purple-Roof concept is making green roofs a true stormwater management tool by incorporating retention and detention .

This frees up space for maximum real estate potential while realizing all other benefits such energy savings, biodiversity, habitat creation, and heat island benefits.

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