RoofBlue Riser


RoofBlue RETAIN is a true “Cradle-to-Cradle” solution for enhanced storm water capture. It captures and retains storm water. Then, after the storm event, it transfers storm water upward to the plant roots, for plant growth and transpiration (to the atmosphere).


RoofBlue RETAIN follows years of development and testing, is supported by university research, and outperformed a typical mineral wool storm water retention product.

  • Can hold 1.35 gallons per square foot (55 liters per square meter) — in addition to the water held by the soil.

  • Can increase storm water retention 42% when paired with the LiveRoof Standard system.

  • Can increase storm water retention 55% when paired with the LiveRoof Lite system.

  • Outperformed mineral wool — 2 in. (50mm) mineral wool + 3 in. (75mm) of soil.

  • Improves irrigation efficiency, especially drip irrigation.

  • Lower cost per gallon of water-retained than other options.


Compared to mineral wool (which has a large carbon footprint and can pose disposal challenges), RoofBlue RETAIN is made from recycled material and is recyclable itself. It could be repurposed 100 years from now.

For more information, please contact any of our dedicated LiveRoof Growers in your area. We are here to help.

RoofBlue® DETAIN

The LiveRoof Integrated RoofBlue® Riser is engineered to provide temporary water detention underneath all LiveRoof systems.  When used with control flow drains, RoofBlue expands the usefulness of a green roof system as a stormwater management tool.  RoofBlue can do the following:

  • Reduce the burden on stormwater systems.

  • May allow for reduced drain size.

  • Reduce or eliminate the need for cisterns, underground storage tanks, and detention ponds.

  • Reduce stormwater utility charges.

  • May qualify for zoning incentives.

  • Reduce overall project cost vs other urban stormwater management tools.

  • Maximum water detention capacity: 455 cubic inches (approximately 2 gallons or 7.4 liters) of water detention per square foot.

  • Dimensions:  24″ L x 12″ W x 3.75″ H

  • Compressive Strength:  min 64 psi [440 kPa] (9200 + pounds per square foot)

  • Simple installation: just set module into riser and slide into place


What is a blue roof?

A blue roof is designed to slow or store stormwater runoff, easing the burden on the stormwater systems.  When combined with the LiveRoof® brand green roof system—which in itself is an effective stormwater tool—the RoofBlue system maximizes rooftop stormwater management capability.  This may greatly reduce the need for other onsite stormwater management tools, such as cisterns, detention ponds, or underground storage tanks.

What is the difference between rooftop detention and rooftop retention? And, which is RoofBlue recommended for?

Retention means that a specific volume of water is retained on the roof for an indefinite period of time.  Detention means to temporarily detain stormwater before discharging it as runoff.

RoofBlue is intended for use as part of a water detention system, whose main function is to delay and control the flow of stormwater runoff.  This delay allows more time for municipalities to treat runoff, which helps to prevent stormwater and combined sewage systems from overflowing (untreated) into local waterways.

How much water can be stored underneath the LiveRoof system using RoofBlue risers?
  • RoofBlue raises the modules an additional 3.5” from the roof surface.  The riser void space is approximately 90.5%.
  • At 3.5”maximum water depth, RoofBlue provides up to 455 cubic inches (approximately 2 gallons or 7.4 litres) of water detention per square foot.
  • The control flow roof drain insert should be even to the lowest point of the green roof installation, the water will not exceed 3.5” in height.  This ensures that the plant roots are kept out of standing water.
A diagram showing the maximum water height in RoofBlue risers.
What is a control flow drain? And, how do I select the right one for my blue roof application?

Control flow drains are designed to slow the rate of runoff from roofs during storm events.  These drains typically have an insert with a weir that regulates the flow of water through the drain.  They are available in a variety of heights.  Generally, flat roofs have lower weir heights than sloped roofs.  Some models have adjustable weirs which can be set for each drain / location, and some may utilize copper flanges to inhibit root growth.  All control flow drain systems should be carefully designed by a licensed professional engineer. These manufacturers sell controlled flow drains:

How much additional weight load does a blue roof add?

RoofBlue applications should be designed to hold no more than 3.5” of water beneath the green roof system.

Each inch of water weighs approximately 5.2 pounds per square foot, so at maximum water detention, the blue roof solution would add up to 18.2 pounds per square foot of load to the weight of the green roof modules (find saturated weights here).

What is the maximum amount of time that rainwater may stand on the rooftop?

In our experience, most roofing assemblies recommend that water does not stand for longer than 24 hours.

However, we recommend that architects and engineers confirm the maximum amount of time allowable for detention with the membrane manufacturer before specifying the type, size and placement of drains and pipes.

Which LiveRoof System Options are recommended for use with RoofBlue®?

The RoofBlue riser is compatible with all LiveRoof module sizes.  The riser will raise the green roof system by an additional 3.5”, which means that taller aluminum edge restraints are required to surround the entire blue / green roof assembly.

Edging Recommendations

  • RoofBlue with the LiveRoof Lite (2.5”) system: Use RoofEdge Deep (6.5″ tall)

  • RoofBlue with the LiveRoof Standard (4.25”) system: Use RoofEdge Maxx (8.5″ tall)

  • RoofBlue with the LiveRoof Deep (6″) or Maxx (8″) systems: Specify an edge restraint of approximately 10.5″ for Deep/RoofBlue or 12.5″ Maxx/RoofBlue (typically custom fabricated).  Alternatively, it may be more economical to use one or more rows of LiveRoof Standard (4.25”) vegetated roof modules at the perimeter and transition to the LiveRoof Deep (6”) or Maxx (8”) systems in the field of the installation.  The modules are designed to integrate between these sizes without edging.

What type of waterproofing system should be used on blue roofs?

Most membrane manufacturers will have special requirements for blue roof applications.   In the early stages of blue roof design, is absolutely critical for engineers and specifiers to work with membrane manufacturers to select appropriate materials, thicknesses and to provide assembly instructions according to local code.

Also, confirm that the waterproofing specification complies with code.  Some municipalities have specific requirements for blue roof applications.  (Example: New York City stormwater construction guidelines address blue roofs).

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