Urban Flood Image

StormCap™+Detention Helps Mitigate Floods

StormCap™+Detention green roof system is engineered to optimize stormwater  management. It detention tool that mimics watersheds and aquifers to help mitigate urban flooding.

Lessens strain on sewers. 

Decreases combined sewer overflow (CSO).

Detention technology allows the green roof to face second day and extra large storms. It is not dependent on weather to provide a repeat performance and recharges in as little as a few hours.  StormCap™+Detention  stores water temporarily and limits the rate at which water flows from the roof drain.



Innovative Technology Mimics Nature

Friction in nature includes tall grasses in meadows, dense masses of reeds in wetlands, or layers of leaves on a forest floor. Friction-detention in

vegetated roofs is a technological innovation inspired by nature to achieve rooftop SWM in dense urban areas.

Contact us to help run stormwater calculations specific to your project.



Clear Return on Investment (ROI)

StormCap™+Detention provides a clear ROI by reducing or eliminating cisterns and bioretention facilities and freeing up valuable space for income-generating development. It even works on a sloped roof!

Stormwater management is unique to each project. Let us start the process and run project-specific calculations.  Contact us for more info.

Other Benefits

  • Provides better plant performance: StormCap™ retains almost double the water of traditional green roofs, and StormCap™+Detention retains about 10-20% more than that! This increases water availabilty for better plant performance.
  • Achieves sustainability goals: StormCap™+Detention is a great way for companies or buildings to show commitment to the environment.
  • Increases real estate values: Green roofs provide usable or visible amenity space that increases rents and real estate value. StormCap™+Detention further increases real estate value by freeing up land
  • Offers greater cooling benefits: All green roofs help cool the building, but StormCap™ and StormCap™+Detention improve cooling by providing more water for evaporative heat loss.
  • Extends roof lifespan: Green roofs buffer the roofing membrane from thermal flux. StormCap™ and StormCap™+Detention do an even better job of this for the same reason that cooling benefits are greater.

Superior Components, Powered by Urbanscape™

The engineered base layers include Urbanscape™’s needled mineral hydro blanket, made solely of virgin rock fibre by Knauf Insulation. This mineral wool has no binders and therefore has superior retention of 90% of water by volume and withstands freeze/thaw cycles.

Most of StormCap™+Detention’s base layers come in rolls that are easy to transport and install. It is a fully customizable system with biodiversity options.  And, can be cut in any shape or size to create logos or icons on the roof!


Construction Canada cover features image of green roof in urban core

  1. Read Technical Article

“Creating Friction in Green Roofs: Reinventing the Traditional Green Roof” 

by Sasha Aguilera and Brad Garner, Construction Canada, October 2019.

Contact us to help run stormwater calculations specific to your project.


Stormwater Capture Co is a one-stop-shop supplying vegetated roof systems customized to local requirements, with warranty and maintenance support. Offer analytical support such as ​stormwater calculations specific to location ​and building/roof type.

Case Study: How the StormCap System is rehabilitating an ailing green roof pioneer and improving functionality for years to come.

The StormCap System is enhanced by Urbanscape for superior stormwater management and plant health.

By Rodney Chaney

The Severn Bank green roof  in Annapolis Maryland (MD) was ahead of its time.  Like many building owners who needed an onsite stormwater solution, this green roof was intended to be a workhorse. With historic rainfall in recent years, it was starting to burn out in sections.  Stormwater Capture Co was invited to inspect the problem and offer a solution to improve its functionality and restore its beauty. Below is the full story about this traditional green roof, now transformed with the StormCap system enhanced by Urbanscape.

Black stallion profile standing outdoors on a cloudy and stormy day.

Green Roof Pioneer: The beginning

The 13,000 square foot Severn green roof sits atop of a four story parking garage connected to a five story office building.  Its primary purpose was to address stormwater management needs near the historic downtown area of Annapolis – likely one of the first in Maryland built for the purpose of managing contributing stormwater.  Tecta America a pioneer in North American green roofs was consulted and contracted to install the roofing and green roof.   Tecta America has diligently maintained the roof since.

Stormwater Workshorse

For years, the green roof had functioned as designed. This workshorse managed well over seven million gallons of stormwater and maintained a healthy plant palette that the owners in the adjacent offices would look upon with pride.  The amenity space within the green roof area has provided a place to enjoy lunch or take a call alfresco.

Fast Forward A Decade Later: “Houston, we have a problem”

The Severn green roof had been designed to accept the contributing runoff from nearly half of the adjacent 20,000 square foot building roof managing the anticipated rain event. It retained both precipitation and runoff.  This workhorse managed twice the amount of water that fell directly on it. It was a great setup and worked beautifully for over a decade. Then, something happened…

Dealing with Historic Rain Events

Two exceptionally wet summers appeared to have caused the green roof to die in several significant areas. This was confusing as two wet summers should not have been enough to make the roof fail. After all, it had been designed to withstand a good bit of runoff.

In the last several years the region has seen historic rain events.  Many site stormwater management systems and municipal storm sewers have

Although many areas of the green roof were lush with excellent coverage other areas had almost completely burned out and in need of rehabilitation.

been overtaxed.

What went wrong and how to fix it?

As symptoms became apparent the owner and Tecta America were quick to act.  Stormwater Capture Co was asked to provide 3rd party consultation.  At the initial inspection, we were surprised to discover that although many areas of the green roof were lush with excellent coverage other areas had almost completely burned out.  What had gone wrong and how could we fix it? Upon closer inspection, we found several contributing factors.

Green roof with wet feet

The overflows designed to manage the onslaught of heavy flow from the contributing roof area hadn’t provided the fail-stop to keep the roof from “bogging out” for extended periods.   Even with a record of 7”+ rain events there was no evidence that the excess flow was reaching the height of the collar to allow for bypass.  Compounding the problem, the drainage assembly at sumps had been built at a time when drain perimeters weren’t typically installed.  In addition, the biomass of over a decade had accumulated to a point where the additional mechanism of evaporation was slow to dry.  While biomass is good, with these other factors this green roof was left with prolonged periods of “wet feet”.

If the green roof needed to manage only the water falling on it, this system would likely have continued to thrive.  However with this pioneer in contributing drainage, it was necessary to move the stormwater throughout the system more efficiently.

StormCap improves roof functionality and restores beauty

To remedy the problem, six hundred linear feet of perforated drain tile was trenched throughout. The indirect pattern allow for improved movement of water to all areas of the green roof.  Then eight expanded drain sumps were opened and framed with new SCC .063 perforated metal edge, SCC drain board, and ballast. Following this, the overflow on the “high side” of the green roof was adjusted by lowering the bypass collar height.  It was factored that 99% of rain events will be treated by the green roof.  So, even in heavy rain events the overflow won’t be tripped too often.

Upon our inspection, we found that only 3,000 square feet out of the total green roof footprint needed replacement.  This was the center of the green roof that received  the majority of contributing drainage.  We decided to solve this problem using several methods.

StormCap berm hosts deeper rooted natives and adaptives such as rudbeckia, asters, beards tongue, russian sage, lavender, phlox and babtisia.

Re-using Native Plants

After removing 3,000 square feet, we were able to reuse all of the nutrient rich biomass that had been built up over the past 12 years to build semi-intensive berms to harbor some deeper rooted natives and adaptives such as rudbeckia, asters, beards tongue, russian sage, lavender, phlox, babtisia, etc.

Not only did this reuse the existing material and help manage the excess of stormwater from the impervious deck area, it also created a great sightline from the amenity area that didn’t exist before.

StormCap Pre Vegetated Roof SystemStormCap Solution

The removed area was replaced with a high efficiency StormCap 1+3 profile by Stormwater Capture Co. Our proven assembly, consisting of  UrbanScape’s® high-performance needled mineral hydro blanket topped by our pre-vegetated mat, provides a healthy and instantly green roof .  This innovative systems now provides the retention needed and stormwater flow necessary to avoid “the bog” that was causing parts to die out in recent years.

Green again! 

After a few days of prep and a Saturday installation, the result amazed the owners Monday morning when they arrived to work.  Their green roof was in fact GREEN again!  The instant coverage of the sedum mat and the addition of the semi-intensive berms surrounding the amenity space were striking.  Less noticeable but more important than the “instant” coverage was the fact that the green roof will now manage stormwater more effectively and be ready for the sunny days well as the storms ahead.

Proud Green Roof Owners

The functional upgrade, and the addition of new visual interest, gave the owners a greater appreciation of what a healthy green roof can provide environmentally and emotionally.  In this scenario, we were able to solve a problem, add functionality, as well as provide a great new aesthetic to this existing “workhorse” green roof.

Your Green Roof Specialist / Design Consultant / Maintenance Support

Stormwater Capture Co offers a single source solution for a complete green roof system package such as the StormCap system. We are a one-stop-shop. Supplier of vegetated mats, high performing base layers, pavers and accessories.  We customize the system to local requirements and provide warranty and support.

Contact us for more info or a free quote on your upcoming project.


Two installers laying down vegetated mat on rock mineral underlayers on highrise flat rooftop.

Engineering Vegetated Roofing Systems to Optimize Stormwater Management

The StormCap™  green roof system  is complete vegetated roofing system. Quality pre-grown mats, engineered growing medium and high performing base layers help achieve long lasting results.Three dimensional image of layers that create the StormCap green roof system

Premium Components:  Enhanced by Urbanscape urbanscape-logo-by-knaufinsulation

Engineered base layers include Urbanscape’s Needled Mineral Hydro Blanket. VFormaldehyde-free, this innovative virgin rock product uses no chemical binders.  The Needled Mineral Hydro Blanket offers an environmental alternative to the other mineral wools on the market and has a superior performance of 90% of water retention by volume.  As a result, it is ideal for vegetated roofs acting as a water reservoir and supporting plant health. Hence, it can supplement or in some cases replace heavy growing media. For these reasons it is an exceptional rooftop stormwater management tool throughout the lifespan of the vegetated roof.

StormCap™ Key Features:

  • Pre-grown, instant “green” with 85% foliar coverage upon installation
  • Stormwater retention 2.6″ (1.6 gal/ft2)
  • Saturated weight 28 lb/ft2
  • Most of StormCap™’s base layers come in rolls for ease of transport and installation

Fully CustomizableImage of biopocket sedum and custom planting options.

The  StormCap™   is a fully customizable system with biodiversity options such as the BioPocket™. There are two BioPocketTM styles: a combination of sedums and perennials or color-blocked sedums-only.  The former requires a deeper depth of growing medium.

A detail rendering of the biopocket inserted in the StormCap vegetated system to create greater biodiversity.

Detail rendering of the BioPocket integrated into the StormCap vegetated system to add biodiversity and greater visual and topographic interest.

Contact us for an estimate or consultation on your roofing project.

Industry leading in performance and engineering

With deep roots in vegetated roofing, Stormwater Capture Co is committed to delivering breakthrough products and services that help with stormwater management solutions.

Stormwater Capture Co offers a single source solution for a complete green roof system package.  We customize your system to local requirements and provide warranty and support.  We are a one-stop-shop supplying vegetated mats, high performing base layers, pavers and accessories.

Green infrastructure offers climate resilience in urban environments.

Green Roofs Mitigate Urban Heat Island Effect

Acacia Smith explains the Albedo Effect. And, how your roof can help fight climate change.

The majority of the roofs in the world are dark-coloured and as a result have a low albedo and absorp excessive amounts of heat.

The majority of the roofs in the world are dark-coloured and as a result have a low albedo and absorp excessive amounts of heat. The ‘albedo’ of a surface is its ability to reflect solar waves; dark surfaces reflect very little whereas light surfaces such as ice have a high albedo and reflective ability. When sunlight hits a white surface, it bounces back and passes through the atmosphere. But once it is absorbed through a dark surface, sun is transformed into heat, which when reflected back during the night cannot pass back through the atmosphere and so remains in circulation.

Urban Heat Island Effect

The low albedo of cities is a problem felt in many urban areas and contributes to the ‘urban heat island effect’ causing deadly heat waves in cities.

The most recognisable outcome of the low albedo of cities is a problem felt in many urban areas throughout the world; the ‘urban heat island effect’ (UHIE). As naturally climate regulating vegetation is removed in favour of infrastructure, cities become pockets of higher temperatures. The difference between heat absorbing urban areas and their surrounding hinterland can be up to 5° degrees. The layers of smog that smother many cities today and the carry on health effects that are increasingly prevalent, are a result of UHIE.


Green Roofs Cool the Atmosphere & The Building

Image depicts a lightweight green roof that captures rainfall and cools the roof compared to the grey roof to the right.

One way to increase the albedo of a roof is to plant vegetation. Rooftop gardens, and green roof systems such as the StormCap, create a buffer preventing heat from entering the building. They have a positive impact on temperature both within the building and outside as well as improving air quality. Green roofs may be one of the only ways possible to reduce UHIE and to adjust the urban fabric of our cities to cope with increasing temperatures and fight against climate change . By regulating temperature variability, green roofs also reduce energy consumption. They provide added insulation in the colder months and prevent excessive heat absorption in the summer.

Vegetated roof reduces the heat flux through the roof.

Vegetated or green roof systems reduce the heat flux through the roof.

Green roofs are gaining popularity rapidly. Several cities are beginning to encourage green roofs through legislature and tax incentives. New York is offering tax rebates to people wishing to install green roofs. Tokyo has a new policy that requires 20% of new government buildings and 10% of private buildings to have green roofs.


“It just doesn’t make sense to leave thatspace unused when we could transform our energy future and reduce urban heat island effects with all the options.” Laurel J. Standley, Ph.D.  ~  Scientist, Author


Acacia Smith wrote the above for the Sustainable Business Toolkit which offers strategies, tactics and tools to help small business grow and propser.  To learn more about what they do click here.


Dedicated to sustainability, NYC Convention Center embodies world-class technological innovation

NYC Convention Center green roof brings nature back to urban core.

The 6.75-acre green roof on the Javits Convention Center makes the 27-year-old building an example of sustainable retrofitting – attracting many species of birds, bats, bees and even tourists who go on rooftop tours.  This NYC landmark is also closely monitored by a team of engineers from Drexel University and The Cooper Union for the Advancement of Science and Art who have designed and installed sensor systems to track its environmental impact.

CEO very pleased with performance of vegetated roof

In a recent interview with NPR (see video below), Javits’ CEO Alan Steel explained the significant aesthetic, environmental and economic benefits of the green roof.

Honey harvested in Fall of 2017 from NYC’s rooftop.

“Besides the great reaction, there are practical benefits.  We have three hundred thousand bees, we’ve seen 25 different species of birds on the roof. We reduced the temperature out here by about six degrees Fahrenheit and we also save about seven million gallons of stormwater runoff that’s absorbed in the  soil and the plants.  We’ve been able to reduce our energy consumption by about twenty six percent and that translated for us last year (2016) into a saving of about three million dollars.”  Javits is now also selling honey harvested from the rooftop.

“The success of our sustainability program epitomizes our rebirth as an organization, and this first batch of honey illustrates how far we have come in our efforts to reduce energy, create a wildlife haven and improve the quality of life in our neighborhood,” said President and CEO Alan Steel.

Green roofs are a learning laboratory for Engineers

Professor Franco Montalto in the department of Civil, Architectural and Environmental Engineering at Drexel College is the lead researcher on the Javits green roof project. He says in recent years the City of New York has made major commitments to sustainability and green infrastructure.

“The Javits Center green roof exemplifies the kind of environmentally sensible urban redevelopment projects that the City wants to encourage. The retrofit building will reduce urban runoff, mitigate the urban heat island effect, and, potentially have a cooling effect on the streets and buildings that surround it. Our research will seek to quantify these benefits,” said Montalto.

Watch NPR feature on Javits

Montalto’s research team is currently also monitoring more than 15 other green infrastructure sites in New York, New Jersey, and Pennsylvania. Students from The Cooper Union will monitor the data and use it to learn about and model functional sustainable design projects.

“The Javits Center green roof project provides Cooper Union students with a significant learning opportunity to study sustainable design and use New York City as a learning laboratory,” said Dr. Joseph Cataldo, a professor in the Albert Nerken School of Engineering at The Cooper Union.  “Our students are presently developing a model to predict the thermal behavior of the green roof using climate and infrared data. This information will be helpful to better gauge hydrology and temperature variations of the green roof, which, subsequently, is an important part of determining and understanding temperature patterns in green roofs and New York City as a whole.”

“Water and energy are intimately linked through the process of evapotranspiration,” Montalto said. “Incident solar radiation changes liquid water, originally deposited on the roof by precipitation, into water vapor which then leaves the roof surface. The energy consumed by this process keeps the roof and building cooler than it otherwise would be, since without the green roof this energy would simply heat up the roof surface. At the same time, if the air in the vicinity of the air conditioner intake pipes is cooler, these units have to work less to cool the -already cooler- building.”

For more on the Drexel and Cooper Union green roof research, click here.

About Stormwater Capture Co – Supplier of High Performing Vegetated Roofs

Stormwater Capture Co supplies green roof systems with high water retention to weight ratio, ideal for retrofits and new builds.

Our team prides itself in being a hassle-free, one-stop-shop supplying vegetated systems that can be customized to local requirements, with warranty and maintenance support. We also offer ​access to a variety of analytical support service​s such as ​stormwater calculations specific to location ​and building/roof type.

Stormwater Capture Co supplies a range of systems from lightweight to biodiverse.  Premium base layers ​include​ the ​Needled ​M​ineral ​H​ydro ​B​lanket.  Sedum blanket and base layers can be easily cut to fit any shape and design.​

Contact us 855-786-7626 or send drawings to info@stormwatercaptureco.com get an estimate for your project.

Copyright © 2018 Stormwater Capture Co. LLC. All rights reserved.

Green roof ‘hail-proof’ while exposed  roofing membrane required replacement

One year ago, the most damaging hailstorm in Colorado history wreaked havoc on cars and roofs and caused $2.3 billion dollars in insurance costs, according to the Rocky Mountain Insurance Information Association.

Dynia Architects designed the 140.,000 square foot FLIGHT building

Denver developer Kyle Zeppelin had hundreds of thousands of dollars in damages to his membrane roofs at his latest office development in The Flight, in the River North District.

“All of the membrane roofing was required to be replaced as a part of the hailstorm,” he said.

While his regular roof had to be thrown out, Zeppelin said he found his luscious green roof – on the same building – was hail-proof.

“The green roof here was left completely intact after the most-recent hailstorm,” he said.

It’s an unseen upside, Zeppelin said, that more than outweighs the upfront costs.

“This is not likely to be the last hailstorm, so there’s that advantage and the green roof provides a significant installation value over just the membrane,” Zeppelin explained. “It’s a win-win as far as [it] makes sense economically, makes sense for the environment, and really enhances the livability of the building,” he said.

Watch news clip and read Jennifer’s full story here.

About Stormwater Capture Com – Supplier of High Performing Vegetated Roofs

Our team prides itself in being a hassle-free, one-stop-shop supplying vegetated systems that can be customized to local requirements, with warranty and maintenance support. We also offer ​access to a variety of analytical support service​s such as ​stormwater calculations specific to location ​and building/roof type.

We specialize in supplying green roof systems with​ high water retention-to weight ratio such as the StormCap system. Our premium base layers ​include​ the ​Needled ​M​ineral ​H​ydro ​B​lanket and can be easily cut to fit any shape and design.​

Contact us 855-786-7626 or send drawings to info@stormwatercaptureco.com get an estimate for your project.

Copyright © 2018 Stormwater Capture Co. LLC. All rights reserved.

13 Apr 2018

How Green Roofs Survive the Northeast’s Bitter Cold, Blizzard and Thaw

Tips for Spring Maintenance and Repair

When it comes to weather, the Northeast US has seen it all this past winter: sub-freezing cold and heavy snow, interspersed with warm dry conditions up to 60°, heavy rainfall, powerful winds, and returning snow storms pounding the region.

With conditions varying quite a bit from week to week, even trees and power lines being felled in high winds, what can we expect from the green roofs high above ground level, invisible to many, quietly doing their job keeping rainfall on-site, among other important environmental functions.


Fig. 2 High performing extensive system.

Many question how a vegetated roof can survive winter and how it will perform in the Spring. Some people question how the vegetation looks. Does the bitter cold, wind and snow damage the plants? Will the green roof die?  Can it be walked on in winter months for necessary rooftop maintenance?  Does vegetation need to be re-seeded in the Spring? Important questions, to which solutions start at the design phase.

Vegetated or green roofs, whether intensive or extensive, experience the same cycles of growth, flowering and dormancy that occur to plants on the ground level. Vegetated roofs that are properly designed for climates with four seasons, correctly installed and routinely maintained, have a greater probability of survival no matter the season, and the changing conditions.  This article will focus on lightweight, extensive vegetated roofs, as this is the prevalent type of vegetated system in the Northeast US and across North America. Extensive roofs use shallower depth of engineered growing media up to 6 inches and are lighter than intensive vegetated systems.  Growing medium may be the traditional soil-based or a lightweight needled mineral wool made solely of virgin rock mineral fibres, or a combination of both for best water-retention-to-weight-ratio (see Fig 2). Extensive roofs can achieve excellent water retention and are more economical to install and maintain.



In cold Northern climates such as the Northeast US, vegetated roofs start going into dormancy in the Fall to prepare for winter. As rooftop conditions are harsher than at the ground level, the exposed vegetation on rooftops enter into the dormancy cycle earlier than at ground level.

Dormancy is a natural reaction to adverse environmental conditions. It is the plant’s defence mechanism to keep itself alive stopping further growth and conserving energy. It occurs each Fall in preparation for the cold winter. It may also happen in the summer during periods of intense heat and drought, if not irrigated.

Dormancy synchronizes with the environment and can be triggered by a temperature drop or sudden changes in climactic conditions, such as water shortage.

Retreating plants are not dead. Green roofs lose their flowers and change colour in dormancy creating a beautiful landscape of reds, bronze and browns, to deep purples. Coniferus sedum plants retreat to form a dense mat of glossy and fleshy leaves, while the leaves of deciduous sedum species completely fall off.

Designing vegetated roofs to survive

Plant type:

For highest probability of survival, a vigorous, low-growing, drought tolerant plant species such as sedums and mosses is the ideal choice.  These plants are tough and reliable and can withstand harsh rooftop conditions year-round.  Sedums are succulent plants that mostly originate in Northern climates and flourish in harsh conditions. Vegetation that is pre-grown outdoors locally, for several months or over a winter, ensures they are acclimatized to the localclimatic conditions.

Foliar coverage:

Mature vegetation, with excellent foliar coverage (85% and higher), not only offers instant green upon installation but a higher probability of survival with less chance of wind and soil erosion.

Thermal mass:

The needled mineral hydro blanket’s high water retention reduces the need for irrigation and improves plant survivability year round.

Snow accumulation is welcome as it insulates the vegetation.  A blanket of snow shelters the vegetated roof from strong winds and helps the plants retain moisture and the blanket of vegetation shelters the growing medium from wind erosion. In colder plant hardiness zones, or in areas where there are extreme fluctuations in temperature, green roofs require a deeper depth of growing medium to help mitigate the effects of intense temperature and moisture changes.  Additional growing medium acts as a thermal mass helping moderate the temperature and hydrate the plants – helping reduce significant die-back in the winter or during hot summer droughts. Water retention materials such as the needled mineral hydro blanket is used to supplement and replace traditional soil-based growing medium and achieves equal or better water storage capacity while keeping the system weight low.

Wind Uplift:

With the recent introduction of CAN/CSA A123.24 Standard Test Method for Wind Uplift Resistance of Modular Vegetated Roof Assembly, the first

such test standard in the world, it is now possible to ensure you choose the right vegetated system for a specific building or certain elevation.


If there is little or no snow accumulation, and the vegetated roof is subject to high winds, extreme fluctuations in temperature or a particularly severe ice storm, plant desiccation, or “winter burn” can occur where the plant dries out and dies. This may expose areas of growing medium that may be subjected to erosion by high winds. If such damage occurs to the vegetated roof, a straightforward procedure for repair can be followed in the Spring. This repair procedure also applies to other vegetated roof repairs due to excessive foot traffic or due to construction materials left on the plants for extended periods of time.

The repair is done in the Spring using a variety of sedum clippings sprinkled, where needed, to replace the sections that have been damaged or eroded.  Succulent plants such as sedums are easy to propagate. Many can be rooted from a single leaf, others will root quickly from a stem cutting. For areas that suffered erosion, additional engineered growing medium should be added, as required. After the initial planting of clippings, frequent, light irrigation is required to keep the vegetated roof moist and help ensure the plants take root.

Installation Tips:

Johnson & Johnson World HQ, New Brunswick, NJ installation in December 2017.

Pre-vegetated sedum mats delivered to J&J site have almost 100% coverage with mature vegetation.

Many vegetated roofs are installed in the Fall due to the construction schedule and desire to finish the project. In such cases, it is critical to have mature and well established plants as they have greater survivability on rooftops than plants that are immature seedlings. The vegetation may have been disturbed during harvest, transport and installation.  Therefore, after installation, it is important to keep the vegetated system hydrated during the establishment period for the plants to recover and take root and prepare for the coming winter.  It is imperative to have water access on the rooftop. Furthermore, good design ensures pavers or ballast is installed to reduce foot traffic and vegetation damage. In cold climates, particularly when temperatures drop below freezing, foot traffic over vegetation must be avoided as it can prove lethal, leaving foot-shaped patches of dead plants. The damage will be obvious the following Spring and recovery may take several months or may not happen at all. If pedestrian traffic is unavoidable, protective measures must be taken to diminish the impact of damage.  Materials like plywood sheets or insulation boards may be laid over the vegetation temporarily to help distribute the weight on the green roof, and removed at the end of each day to allow plants to recover.

Fall & Spring Maintenance:

Year-round maintenance is key to ensuring long-term survivability as well as the stormwater performance of the vegetated roofs.  One last maintenance check should be done in the Fall as part of the yearly routine.  Vegetated roofs are also known for their ability to protect the roof membrane, however, not taking proper preventative measures can also lead to unforeseen problems.

Fall maintenance includes the removal of debris and inspection of all drainage paths.

In Fall, it is best to remove fallen leaves and twigs from the green roof. Thick layers of leaves and twigs can also stick together to form an impenetrable mat and may lock in too much moisture, potentially causing rot or damage to the plants.

Weed, one last time, before winter sets in. Make every effort to capture the seed pod intact and tuck it away for disposal to avoid seeds blowing away.  Some weeds may be tolerated, therefore maintenance personnel should be familiar with green roof plants and the owner’s green roof aesthetic preference.

Keeping the vegetated roof hydrated into the Fall months helps the vegetation avoid winter’s freeze-drying effect caused by low temperatures and high winds.

If there is an irrigation system, it needs to be winterized around October in nothern States as frost typically sets in soon after. Maintenance crews typically use an air compressor to blow out the water from the irrigation system.

Vegetated roofs should not be fertilized past August, especially with a slow release type fertilizer. Fertilization may stimulate tender growth and compromise the hardiness of the plant. Secondly, plants won’t have a chance to fully take up the nutrients and the combination of high temperatures may cause the plants to burn. Slow release fertilizer is usually applied once, ideally in the Spring.

Assess the performance of the green roof in the Fall and prepare for next Spring.  It is a good idea to document  your visit with photos and record recent weather conditions for future reference and any potential warranty claims.

About Stormwater Capture Co

Our team prides itself in being a hassle-free, one-stop-shop supplying vegetated systems that can be customized to local requirements, with warranty and maintenance support. We also offer ​access to a variety of analytical support service​s such as ​stormwater calculations specific to location ​and building/roof type.

We specialize in supplying green roof systems with​ high water retention-to weight ratio such as the StormCap system. Our premium base layers ​include​ the ​Needled ​M​ineral ​H​ydro ​B​lanket and can be easily cut to fit any shape and design.​

Contact us 855-786-7626 or send drawings to info@stormwatercaptureco.com get an estimate for your project.

Copyright © 2018 Stormwater Capture Co. LLC. All rights reserved.

StormCap pre vegetated roof system

The StormCap vegetated roof system above uses Needled Mineral Hydro Blanket and retains 2.6 inches of rainfall. Photo: Greg Van Riel


Vegetated roofing has long been recognized as an effective stormwater management tool in urban centres to help store and attenuate runoff from impervious rooftops. New technological advancements are helping further increase stormwater retention capacity on rooftops while keeping weight low.

One such significant advancement is the use of rock mineral wool (RMW)—which offers both advantages—in place of a greater depth of traditional growing medium. There are several varieties of mineral wool on the market, produced for different applications.



When it comes to stormwater retention and vegetated roof survivability, not all mineral wools are created equal.


Mineral wool is a general term for a light, artificial wool made of an inorganic substance such as glass, stone, or slag. It was originally invented in the mid-19th century for thermal and acoustic insulation in the construction industry.

Almost 50 years ago, a modified form of RMW in the form of slabs, blocks, and bonded fibres started being used as a substrate in hydroponics in Denmark. (For more, read the 2002 article, “Substrates and their Analysis” by M. Raviv et al., published in D. Savvas and H. Passam’s Hydroponic Production of Vegetables and Ornamentals by Embryo Publications in Greece.) Today, it is present in virtually all advanced horticultural markets, and is used for growing hydroponic fruits, vegetables, herbs, and flowers.

RMW for vegetated roofing applications is manufactured by a fiberization process induced by heating a mixture of various rock components (usually diabase, dolomite, granite, basalt, etc.), which are melted together at high temperatures. (Further information on mineral wool production can be found in B. Širok et al.’s 2008 publication Mineral Wool Production and Properties from England’s Woodhead Publishing Limited.) The melt is spun into thin fibres on fast-rotating machines and is later bound for dimensional stability.

Generally, there are two major differences between methods of making the loose, melted rock fibres dimensionally stable and transforming them into slabs, blocks, or wool. They can be bound using a chemical-free needling process to physically interconnect loose fibres, or those loose mineral wool fibres can be glued with binders. Examples of the latter option include:
• sodium silicates;
• polyesters;
• melamine urea formaldehyde;
• polyamides;
• resin-based phenolic; or
• furane-based resins. (From Kowatsch’s article, “Mineral Wool Insulation Binders,” published in Phenolic Resins: A Century in Progress from 2010.)


Advancements have been made in the manufacture of mineral wool over the decades, offering environmental alternatives and products with superior performance. One development has been the use of formaldehyde-free binders, which rely on renewable resources. This new generation of mineral wool is an environmentally responsible alternative to phenol-based products. It uses renewable resources for binding agents and has enhanced water absorption characteristics. The most notable development is the production of the needled rock mineral wool, the Needled Mineral Hydro Blanket, Hydro Cubes and Hydro Flocks, manufactured without additives or binders.


The high water retention of needled or binderless mineral wool (Hydro Blanket above, Hydro Cubes and Flocks) reduces the need for irrigation and improves plant survivability. Photos: Knauf Insulation

hydro cubes

Hydro Cubes and Flocks are designed to be mixed with traditional growing media to increase rainwater holding capacity.


Flocks and Cubes are recommended for containers, patios, and ground level landscaping and contribute to better soil structure, water-holding capacity, and aeration of growing media.











It is important to understand how this engineered product supports long-term stability and stormwater retention performance in outdoor applications such as vegetated roofing. Needled rock mineral wool can be ideal for vegetated roofs, as it acts as a water reservoir and supports plant health, replaces heavy growing media, and performs exceptionally as a rooftop stormwater management tool throughout the lifespan of the vegetated roof.

Categories of rock mineral wool

Installation of Needled Mineral Hydro Blanket on Camden, NJ school rooftop.

Various types of RMW are currently available, each complete with its own unique advantages, drawbacks, and properties.

They are those that use 1) traditional chemical binders, 2) bio-based binders, and 3) needled or binderless RMW. The latter is the most recent innovation in RMW. Below are details why binderless RMW is ideal for vegetated roofs.

1) Traditional binders

The most common mineral wool on the market is sprayed or bound with phenolic resin or diluted phenol-formaldehyde (PF) for dimensional stability. These binders also help make the product water-repellent. This type of mineral wool is typically used as insulation in the construction industry. When traditional mineral wool is modified with a hydrophilic (or wetting) agent, it can be used as a growing media for hydroponic cultivation in a strictly controlled environment. If this type of mineral wool is used as an alternative to other growing media, it requires uniform conditions such as a greenhouse where usage cycles tend to be relatively short (i.e. from one growing season to five, in the case of ornamental plants). If it is exposed to any varying, uncontrolled climatic conditions (e.g. dry/wet periods, freeze/thaw cycles, or high/low temperatures) for longer periods, its water-holding characteristics will change significantly, resulting in decreased hydrophilic ability. In other words, cycles of drought or precipitation will negatively influence the material’s long-term performance and its water absorption capacity. This phenomenon likely occurs due to the hydrophilic agent rinsing out, which causes the initial hydrophobic character to prevail. Therefore, traditional mineral wool is not ideal for outdoor applications such as vegetated roofing. Its hydrophobic propensity renders it an inconsistent and unreliable stormwater management product over time, unable to effectively sustain rooftop plants under significant stress in hot and dry seasons.

2) Formaldehyde-free binders

A new generation of mineral wool providing a solid alternative to the traditional variety has been invented and commercialized in the last decade. Bound together using a bio-based technology, this mineral wool is free from formaldehyde, phenols, and acrylics and uses no additional artificial colours, bleaches, or dyes. This reduces harmful manufacturing emissions and workplace exposures, improving the overall sustainability of buildings into which the product is incorporated.

However, as with traditional mineral wool, bio-based binders will typically render the mineral fibres hydrophobic. A hydrophilic agent must be added to improve the hydrophilic capacity of the material. While mineral wool with bio-based binders will retain more water than phenol-based mineral wool, its long-term water absorption capacity decreases, as it does with the phenol-based variety, due to the flushing of the hydrophilic agent during periods of drought and precipitation.

3) Needled or binderless innovation

Fig 1. Needled rock mineral wool without binders—virgin material (SEM analysis, zoom 1000x).

The most recent advancement in this industry is the manufacture of needled rock mineral wool—a non-petroleum-based and formaldehyde-free alternative. Products made this way are known as Needled Mineral Hydro Blanket, Cubes or Flocks. The needling process provides dimensional stability without the use of any binders—mineral wool is formed by a mechanical interconnection of pure mineral fibres. This process forms a structurally stable, lightweight, and porous material with longer fibres (Figure 1) that can maintain excellent water-holding properties. It is consistently hydrophilic, even after varying weather cycles throughout the year. The material can hold 90 per cent of its volume in water. When wet, the majority of the retained water is easily available for plants’ uptake. (This was tested by pH curve. The authors can provide data upon request.) A minimum of 10 per cent oxygen is left in the needled mineral wool, enough to support the oxygen levels in the root zone and, therefore, healthy roots. The material is inert, with chemically stable fibres. On the left side of Figure 1, the condition of fibres three years after installation is shown with soil particles attached.




Fig 2. Needled rock mineral wool after three years of installation (SEM analysis 800x). Photos courtesy Institute Jožef Štefan

The hydrophilic characteristics of the Needled Mineral Hydro Blanket can offer long-term stability, as nothing rinses away. The physical attraction between fibres and water remains the same throughout the lifetime of the product.  Binderless mineral wool offers hydrophilic characteristics that better support root growth and overall plant health, making particularly suitable for many vegetated roof applications, with long-term survivability in various climatic zones.







Needled or Binderless Mineral Wool is Ideal for Vegetated Roofs

Needled mineral hydro blanket absorbs stormwater and feeds plants for improved survivability. It also reduces the need for irrigation

• It is lightweight;
• It can supplement or, in some cases, replace heavy growing media;
• It can act as a water reservoir while supporting plant health;
• It achieves more credits under the Leadership in Energy and Environmental Design (LEED) program (The material contributes to eight additional points under LEED v4. These include credits in the Sustainable Sites [Protect or Restore Habitat, Open Space, Rainwater Management, and Heat Island Reduction], Energy and Atmosphere [Optimize Energy Performance], Materials and Resources [Environmental Product Declarations], and Indoor Environmental Quality [Thermal Comfort and Acoustic Performance] categories.); and
• It performs exceptionally and reliably as a rooftop stormwater management tool throughout the lifespan of the vegetated roof (as seen on Sweden’s Karolinska University Hospital, Rentenversicherung headquarters in Berlin, and various projects throughout Baltic and Scandinavian countries).

Needled Mineral Hydro Blanket comes in a roll and has a density of 286 to 319 lb/35 cf. It is also available as Hydro Cubes (0.8 x 0.8 in) and Hydro Flocks (0.1 to 0.8 in.) and is recommended for containers, patios, terraces and ground level landscaping applications. Cubes and flocks are added to a traditional growing medium and contribute to better soil structure, water-holding capacity, and aeration. The retained rainwater inside the Hydro Cubes or Hydro Flocks is easily available for plant uptake and improves plant survivability.

Research and analyses

As the needled manufacturing process does not require binders, it ensures the product’s natural hydrophilicity remains intact, making it highly reliable for long-term stormwater management performance in vegetated roofs (Figure 2).When it comes to long-term water absorption, research shows needled mineral wool (Hydro Blanket, Cubes and Flocks) designed for growing plants outperforms traditional horticultural RMW by up to three times. Water uptake (WOK) analysis is used to determine this. This method shows the velocity of water absorption in time for specific substrates. After saturating and drying out, the capacity of absorption is measured for 1500 minutes. The results show long-term water absorption of needled mineral wool for growing plants is 70 per cent, whereas traditional phenol-based horticultural mineral wool absorbs significantly less—between 20 and 35 per cent. (Water uptake analysis test method developed by Regeling HandelsPotgronden [RHP], Netherlands.)


Fig 4. Stormwater testing lab in Virginia.

As experience and numerous studies show, RMWs using binders are commonly recognized as products for hydroponic growing, and the needled or binderless type—due to its unique characteristics—is ideal for outdoor environments. For example, it can be used in vegetated roofs for significant improvement of stormwater performance and roof longevity in different climate zones. Research indicates RMW positively influences plant growth and development on vegetated roofs as well as in other applications. (From D. Majkovič et al.’s 2016 presentation, “Promote Vegetated Roof Stormwater Performance with Mineral Wool Layer,” from Cities Alive in Washington D.C. Also from C. Arkar et al’s 2015 publication, “Lightweight Green Roofs’ Thermal Response Under Freezing Conditions,” from Energy Procedia 78.) It also showed great potential in container substrates as an alternative growing medium in the 1990s. (The study that determined this can be found in W.C. Fonteno and P.V. Nelson’s Physical Properties of and Plant Responses to Rockwool-amended Media, published in 1990 by the Journal of the American Society for Horticultural Science.) Applications of the new generation of Needled Mineral Hydro Blanket confirms this finding. (See A. Šušek et al’s presentation from Ramiran 2015 at the Hamburg University of Technology, “The Impact of Rock Mineral Wool on Water Retention in a Conventional Growth Medium, and Development of Zonal Pelargoniums.”)

Fig 5

Vegetated roofs constructed with binder-free needled mineral wool are tested and have been applied in various climate zones from moderate to extreme. Going forward, the focus continues to be on stormwater performance in retention testing, where vegetated roofs with a needled mineral wool layer are compared to traditional, engineered-growing-media-based vegetated roofs. One stormwater testing laboratory in Virginia (Figure 4) uses custom technology to apply replicable computerized rain events mimicking real-life rain events to evaluate assemblies 80 sf in size. In Figure 5, the quantity of water retention and transient water is shown as measured on those samples in 90 minutes. Full and dotted blue lines represent the values for a vegetated roof with a binder-free needled mineral wool layer, which is nearly doubled in stormwater performance compared to a 4-in. vegetated roof with traditional engineered growing media only (shown with grey full and dotted lines in Figure 5). The mineral wool layer does not significantly affect the dynamics of the release, but strongly influences the quantity.

Fig 6

The second graph (Figure 6) indicates stormwater performance is equivalent between a 101-mm vegetated roof with a needled mineral wool layer to which 72 gal is applied after 90 minutes (again, shown with blue full and dotted lines) and a 8-in. vegetated roof without a mineral wool layer (with 68 gal applied after 90 minutes). Introducing the needled mineral wool layer on the roof leads to significant load savings and the possibility of applying this solution when retrofitting. (Mineral wool weighs approximately 10 times less than the same amount of soil.)


Technological developments in needled or binderless mineral wool over the last decade have focused on increasing water retention and maintaining long-term performance. Needled mineral wool’s characteristics better support root growth and overall plant health in various climatic zones, from hot and arid to frigid and wet, whether used in indoor applications such as urban farming or outdoor applications such as landscaping or vegetated roofing. Having been used in Europe for the past decade—with the largest projects being in Scandinavia, the Baltic States, and Germany—needled mineral wool has recently become available in North America, providing American designers and engineers a viable solution to landscaping in arid areas and increasing the stormwater management capacity on rooftops where this would otherwise be impossible.



A performance evaluation tool developed in collaboration with the Laboratory for Sustainable Technologies in Buildings, University of Ljubljana, helps assess the real performance of a defined roofing system in any city in the world or in different climate zones. A software package was created from its results
Photo courtesy Knauf Insulation

To help design/construction professionals more effectively create vegetated roofs, various manufacturers are introducing new tools and software to the industry. In collaboration with the Faculty of Mechanical Engineering’s Laboratory for Sustainable Technologies in Buildings at the University of Ljubljana, Slovenia, one company has developed a performance evaluation tool as a result of a two-year in-situ performance study of different types of vegetated roof systems. This tool helps assess the real performance of a defined roofing system in any city in the world or in different climate zones.

The University of Ljubljana test and evaluation has been ongoing since 2014, and the initial two-year results have been used to create a software package intended to help current and potential users and owners of extensive vegetated roofs understand the real performance they can expect. As well as vegetated roofs’ stormwater performance, this software provides data on how such roofs can improve buildings’ energy performance and how they can reduce heat island effect.

Darja Majkovič is the head of products and applications in green solutions at Knauf Insulation. For nearly a decade, Majkovič was a researcher at the University of Maribor, focusing on agricultural economics and econometrics. Her work includes collaboration on numerous national and international research and development projects. Majkovič was a visiting researcher at the French National Institute for Agricultural Research (INRA) and a university lecturer, and has written more than 160 articles. 

Jure Šumi is the business development director at Knauf Insulation, leading several teams. These include “Urban Green Infrastructure,” which focuses on developing lightweight green roof systems for stormwater management, “Landscaping and Gardening,” which focuses on developing substrates and systems for water conservation in arid climates, and “Horticulture,” which focuses on developing environmentally responsible hydroponic alternatives. Šumi has more than 20 years of experience in business and market development for multinational companies in a variety of sectors. 

Cristina Senjug serves as the communications manager at Stormwater Capture Co.  

Stormwater Capture Co prides itself in being a hassle-free, one-stop-shop supplying vegetated systems that can be customized to local requirements, with warranty and maintenance support. We also offer ​access to a variety of analytical support service​s such as ​stormwater calculations specific to location ​and building/roof type.

We specialize in supplying green roof systems with​ high water retention-to weight ratio such as the StormCap system. Our premium base layers ​include​ the ​Needled ​M​ineral ​H​ydro ​B​lanket and can be easily cut to fit any shape and design.​

Contact us 855-786-7626 or send drawings to info@stormwatercaptureco.com get an estimate for your project.

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