rooflite® FAQ

What is green roof growing media?
How long will rooflite® growing media last?
What are the advantages of having a certified quality green roof media?
What are the advantages of a standardized material?
Does one growing media work everywhere?
Do rooflite® growing media products need to be replaced or added after a certain time?
What drainage systems can be used in combination with rooflite® growing media?
Which green roof systems can be used in combination with rooflite® growing media?
Does rooflite® work in modular green roof systems, in containers, and in planters?
What is the weight of rooflite® growing media?
Does compaction have to be considered?
How long is the shelf life of rooflite® growing media?
Are there any installation instructions for rooflite® growing media?
How can rooflite® growing media be conveyed to the roof onsite?
Which plants can be used with rooflite® growing media?

What is green roof growing media?

Green roof growing media can be defined as an engineered soil that both mimics and improves on the properties of natural soil. Native soil is the product of a natural process that has occurred over thousands of years. Although native soil works perfectly in its natural environment, it cannot be used on green roofs due to its excessive weights, its inability to retain sufficient amounts of moisture, as well as its inability to drain excessive amounts of moisture properly.

On the other hand, green roof growing media faces several additional requirements since it ultimately must promote plant life in an environment which is very different from the natural surroundings of these plants.

In short, an ideal growing medium should support plant growth, be lightweight, and should retain and drain water simultaneously. It also must perform all of these functions in an extremely shallow system.

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How long will rooflite® growing media last?

There is no limitation to the service life of rooflite® growing media. Carefully selected mineral components create a stable and durable structure which guarantees longevity.

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What are the advantages of having a certified quality green roof media?

All rooflite® green roof media products have the following properties:

  • Lightweight to minimize the roof load
  • Heavy enough not to get dislocated by wind or flowing water
  • Stable to give plants sufficient hold
  • Low compaction, insignificant bulk density loss
  • Resistant to frost and fire
  • Retain rain water
  • Drain excess water
  • Sufficiently aerated to promote root growth
  • Have the right level of acidity
  • Salt content is tested for acceptable levels
  • Proper amount of nutrients.

If your growing media is not certified quality, your green roof may be unsuccessful if:

  • The media contains components which are harmful to plant life
  • The media is not fire resistant
  • Grain sizes are not appropriate or not balanced
  • The organic content is too high or too low
  • Components are not frost resistant
  • The media structure is not stable
  • Components are too light and get washed or blown away
  • Excess water cannot percolate through fast enough
  • There are not enough air filled pores
  • The pH level is too high or too low
  • The salt content is too high
  • The level of nutrients is not adequate
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What are the advantages of a standardized material?

Many of the initial green roofs built in North America were installed using “individual solutions”. In other words, green roofs were installed on a “custom” basis without using properly tested specifications and material. As such, custom made solutions are complicated and costly due to the many unforeseen changes in using unspecified techniques and material. Additionally, they can produce a higher risk of failure. Standardization makes it easier, safer, and more affordable to plan and build green roofs.

Skyland USA LLC has created a registered, standardized solution which allows green roof construction to be:

  • Easier for architects to specify and easier for the contractor to calculate and purchase materials.
  • Safer to specify for contractors.
  • Cost effective for the client because our standardized material can be produced and handled more efficiently.

Standardization is also the key for marketing green roof media products on a larger scale and to achieve product availability nationwide.

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Does one growing media work everywhere?

All rooflite® growing media products comply with all FLL and ASTM requirements. However, these requirements give a range which allows for regional or even project specific adjustments. rooflite® blenders in the different regions of North America have specific rooflite® formulations based on the availability of cost effective raw materials. Additionally, formulations are adjusted for regional climate conditions.

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Do rooflite® growing media products need to be replaced or added after a certain time?

When calculating material demands, it is crucial to consider compaction. If compaction is taken into consideration during the planning of your green roof and your green roof is properly maintained, you should not need to replace or add additional material.

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What drainage systems can be used in combination with rooflite® growing media?

Although rooflite® drain is the ideal drainage material in combination with rooflite® growing media, any drainage system which complies with FLL and ASTM requirements can be used.

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Which green roof systems can be used in combination with rooflite® growing media?

rooflite® has been created in three formulas, rooflite® extensive, rooflite® semi-intensive, and rooflite® intensive, in order to meet all of your green roof needs. All rooflite® products work collaboratively with any corresponding green roof system complying with FLL and ASTM standards.

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Does rooflite® work in modular green roof systems, in containers, and in planters?

® growing media has been used in various green roof modules, containers, and planters with long lasting success. As long as sufficient drainage is provided, rooflite® growing media will perform exceptionally well.

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What is the weight of rooflite® growing media?

The average bulk density of rooflite® growing media is 72 - 74 lb/ft3 saturated (at maximum water holding capacity). For more detailed specifications about a particular blend, please refer to our products page which contain more information or feel free to contact us directly.

Note: Bulk density values in FLL based test reports are referring to compacted media samples.

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Does compaction have to be considered?

When calculating the amount of material needed for your project, it is very important to consider compaction! If compaction is not considered, you will run the risk of having a failed green roof because your plants will not have the proper amount of growing media or you will spend additional money on material and delivery costs by ordering additional material to cover the compaction amount not initially considered. Basically, by keeping compaction in mind, you will save time and money.

Your rooflite® order should be approximately 115% to 120% of your calculated demand based on the net green roof area (length, width, and depth) (discounting gravel strips, firebreaks, pavers, patios, etc.) and the requested media depth after compaction.

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How long is the shelf life of rooflite® growing media?

The shelf life of rooflite® media is limited by the following factors:

  • Danger of contamination of bulk material or open totes by foreign substances or weed seeds.
  • Compaction of material in totes. This may affect the ability to empty the totes.
  • UV-radiation affecting totes or bags exposed to sun light.
  • Precipitation does not influence the quality of rooflite® products. However, long periods of rain may increase weight and shipping costs and may affect pneumatic conveyance.
  • Frost may affect the usability of rooflite® products. Frozen media cannot be installed and will need extended time to thaw prior to use.
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Are there any installation instructions for rooflite® growing media?

General instructions for the installation of rooflite® growing media are:

  • Avoid overburdening structural capacity of roof deck;
  • Avoid sudden impact of heavy loads on the roof;
  • Avoid affecting the integrity of underlying layers of green roof system;
  • Keep growing media from under the filter fabric;
  • Keep growing media from contaminating surrounding areas;
  • Observe specified media depth;
  • Check depth of readily placed media frequently;
  • Consider compaction;
  • Avoid using installed areas for transportation;
  • Protect areas being used for transportation;
  • Level out surface evenly according to specifications and drawings;
  • Avoid contamination of growing media; and
  • Protect integrity of growing media.
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How can rooflite® growing media be conveyed to the roof onsite?

Main transportation devices for rooflite® products onsite are cranes, conveyor belts, or blower trucks. Many factors have to be considered in order to find the best option for a specific project including height and size of the building, accessibility of the roof, size and design of the green roof as well as other criteria which can influence onsite transportation. Independent upon the method of delivery, factors that could restrict delivery must be considered. For example: Can a tractor trailer fit down this street? Will I set the material on the ground before moving it to the roof? How many loads do I have room for in a day? Is their overhead clearance for a dump truck? Are their truck restricted routes on the way to my job site? Can my equipment handle the packaging? How much time is included from the trucking company for offloading?

Onsite transportation of green roof media is a crucial factor for calculating costs of green roof installation. Excellent flowability for pneumatic conveyance is a special characteristic and an added value of rooflite® products.

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Which plants can be used with rooflite® growing media?

While 2”- 4” of rooflite® extensive mc will support hardy succulents like Sedum and Delosperma species, a depth of 5” or more will also support other hardy perennials and grasses.

5” or more of rooflite® semi-intensive will support a wide range of perennials, grasses, and even small growing shrubs and evergreens depending on the construction, depth, and irrigation.

rooflite® intensive is the ideal media for long lasting, healthy plant growth including ground covers, ornamental grasses, shrubs, and trees.

Plant selection does not only depend on the type and the depth of the growing medium, regional climates and project specific factors are also crucial for the long term success of your planting.

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