Frequently Asked Questions

More information about rainwater infiltration</a></span></p>"},{"question":"What is Rockflow made of?","answer":"<p>Rockflow stone wool elements are made from the raw material basalt and <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/this-is-how-rockflow-works/fully-circular//">recycled stone wool</a>.</p>"},{"question":"What is a swale?","answer":"<p>A swale is a water-permeable buffer that fills up with water in the event of rainfall and discharges it to the ground. A swale is often a ditch or trench with a water-permeable base.</p><p>A traditional swale usually consists of a layer of soil with plants. The swale collects the rainwater, and slowly releases it into the ground. But because the space is often limited, a swale must be relatively deep in order to be able to collect sufficient rainwater. A Rockflow infiltration system can be installed beneath the layer of earth and plants, thereby creating more space for the collection of water. Thanks to the stone wool elements, a swale containing Rockflow stone wool is also shallower than the traditional variant.</p><p><span class=\"btn is-small\"><a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/solutions/swale//">More information about swales</a></span></p>"},{"question":"What is the k-value of Rockflow?","answer":"<p>The permeability of the soil is expressed by the k-value, also known as permeability or hydraulic conductivity. A k-value of 1 means that a raindrop travels 1 metre in a 24-hour period. The k-value is an important value, as it maps out the permeability of an infiltration facility.</p><p>The k-value of Rockflow stone wool is 50 to 200 metres per 24 hours, depending on the type of stone wool used. The k-value of the Rockflow water management system is therefore comparable to that of coarse sand or fine gravel.</p>"},{"question":"Does stone wool cause irritation?","answer":"<p>Although stone wool is a safe material, temporary irritation (itching) may occur when working with it. To minimise this, we recommend that you always take the following measures when working with stone wool products outdoors:</p><ul><li>Wear body-covering clothing (long sleeves and gloves);</li><li>Wear a dust mask and/or safety goggles;</li><li>Rinse off your skin with cold water.</li></ul><p><span class=\"btn is-small\"><a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/downloads/safe-use-instruction-sheets//">More information about working safely with stone wool</a></span></p>"},{"question":"What is the difference between Rockflow and the stone wool used in insulation?","answer":"<p>The main difference is that stone wool used for insulation is made to be water-repellent, while a Rockflow element can absorb up to 95% of its volume in water.</p><p><span class=\"btn is-small\"><a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/this-is-how-rockflow-works//">More information on the infiltration of rainwater</a></span></p>"},{"question":"Is there a CE mark for the material? ","answer":"<p>There is currently no CE mark for Rockflow stone wool, partly because the combination of stone wool and water management is not yet standardised. Rockflow is expected to have the CE mark and Declaration of Performance in 2023.&nbsp;</p>"},{"question":"Is it possible to place playground equipment above a Rockflow buffer?","answer":"<p>Yes, objects such as playground equipment can be placed above a Rockflow buffer. Please note: the buffer must not be damaged during installation and the forces of the devices must be well distributed over the surface. Please contact the <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/contact//">Rockflow team</a> for the specific installation.</p>"},{"question":"How quickly is water distributed in the Rockflow system when it enters the stone wool via the water channels?","answer":"<p>The permeability of Rockflow stone wool is approx. <u>100</u>&nbsp;<u>m/24 hours</u>. Rockflow systems are always designed so that every system, regardless of its size, is completely filled within <u>15 minutes</u>.The upstream supply is often the limiting factor rather than the water permeability of the stone wool itself. This principle remains the same for larger systems with multiple input channels.</p>"}]},"installation":{"name":"Installation","questions":[{"question":"What other provisions must be applied for a Rockflow buffer (e.g. venting, overflowing, a third system)?","answer":"<p>The other provisions to be applied depend on the situation and the design. A Rockflow buffer is a part of a system, and is therefore normally combined with distribution pipes, distribution wells, inspection wells, gullies, venting, overflows, etc.</p><p>Are you looking for technical support for the installation of a Rockflow buffer? Contact the <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/installation-of-rockflow/construction-team//">Rockflow team</a>.</p>"},{"question":"What are the dimensions of Rockflow?","answer":"<p>Rockflow elements are available in a number of standard dimensions. A Rockflow system can be built from 33, 50, 66 and 100 cm high elements. All elements are 1.20 m long and 15 cm wide.&nbsp;</p><p><span class=\"btn is-small\"><a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/installation-of-rockflow/designing-a-rockflow-system//">More information about designing a Rockflow buffer</a></span></p>"},{"question":"What does a Rockflow element weigh?","answer":"<p>Rockflow elements are available in a number of standard sizes and densities. The heaviest element weighs 22 kg. This makes it easy to install the elements by hand without the need for special tools.</p>"},{"question":"What is the maximum speed of installation? ","answer":"<p>The installation speed depends on various factors, such as the work preparation and the logistics process for the supply of materials. Depending on the design, a Rockflow system can be installed at a speed of 25-30 sqm per hour by two ground workers and a crane operator. Our own record is 60 sqm/hr with 4 people.</p>"}]},"sustainability & circularity":{"name":"Sustainability & circularity","questions":[{"question":"How sustainable is stone wool?","answer":"<p>Rockflow elements are <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/this-is-how-rockflow-works/fully-circular//">made of fully circular stone wool.</a> Stone wool is made from the inexhaustible raw material basalt combined with recycled stone wool.</p><p>The Rockflow <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/downloads/life-cycle-assessment-and-environment-product-declarations-rockflow//">life cycle analysis</a> shows that in many cases stone wool is advantageous in terms of environmental impact compared to alternative solutions.&nbsp;</p><p>More information on sustainability goals can be found in <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/downloads/rockwool-group-sustainability-report//" target=\"_blank\" rel=\"noopener\">the ROCKWOOL sustainability report</a>.</p>"},{"question":"How much recycled material is already in the Rockflow products?","answer":"<p>The stone wool products fit perfectly into a <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/this-is-how-rockflow-works/fully-circular//">sustainable and circular economy</a>. Stone wool is a natural product that is made from volcanic basalt rock. Stone wool is fully recyclable at the end of its life cycle, while maintaining quality and without loss of performance. The Rockflow elements contain approximately 50% recycled materials.</p>"},{"question":"Is it possible to make collected rainwater available for reuse?","answer":"<p>Stone wool collects rainwater and allows it to infiltrate into the soil. In addition, a water-containing layer can be created by a capillary break, which supplies a surface green layer with water (e.g. the municipality of <a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/solutions/swale/rockflow-project-zoeterwoude//">Zoeterwoude).

"}]},"maintenance & service life":{"name":"Maintenance & service life","questions":[{"question":"Is stone wool susceptible to ravenous pests?","answer":"<p>To date, no evidence has been found of deterioration of Rockflow stone wool due to ravenous pests. Due to the relatively high density of stone wool, it is difficult for vermin to penetrate.</p>"},{"question":"Is annual maintenance required for Rockflow stone wool? ","answer":"<p>The need for annual maintenance for Rockflow stone wool depends on the situation and how the system is applied.</p><p>Rockflow systems are very easy to inspect. The water channels can be visually inspected using a push camera and/or robot camera.</p><p>If necessary, the water channels can be cleaned. They can be flushed using a standard high-pressure sprayer at a pressure of 50&ndash;80 bar and using a 0<strong>&deg;-</strong> nozzle. This method allows the sediment to move toward the well, where it can be sucked up. It is recommended to inspect the channel before cleaning.</p><p>It is also possible to keep the channels in the system clean using a sand trap and blade separator.&nbsp;</p><p><a href=https://www.rockwool.com/"/group/products-and-applications/rockflow/this-is-how-rockflow-works/long-service-life-and-easy-maintenance//">

Rockflow in generalInstallationSustainability & circularityMaintenance & service life

Rockflow in general

Rockflow in general

Installation

Sustainability & circularity

Maintenance & service life

Rockflow in general

Does stone wool absorb water from the overlying ground?

No. Because soil and substrate have a higher suction pressure than stone wool, no water is extracted from the soil or substrate.

What is suction pressure?

Suction pressure is a characteristic of the water absorption capacity. Among other things, this is determined by the capillarity and the amount of water present in the material. In the case of soil and substrates, this suction pressure is always higher than that of stone wool. Stone wool therefore cannot extract water from the ground.

What is the density of Rockflow?

Among other things, the density of Rockflow ensures a high load-bearing capacity. The basic material is stone wool, which has all the properties of stone. Vehicles can park on top of the system without the elements losing their shape or functionality.

Rockflow is available in various densities. The most commonly used density is 5%. The remaining 95% is therefore available for the absorption of rainwater.

What is Rockflow’s emptying time?

Rockflow stone wool has an outflow speed of 100 metres/24 hours. Taking into account the k-value of the substrate, a system is always designed to be completely empty and available again 24 hours after a shower. If this is not achieved due to a low k-value, the system is designed to undergo sufficient deflation via a delayed discharge (pinch construction).

Thanks to the large infiltration surface of stone wool, infiltration even on poorly permeable soil types such as clay is an option. Water absorption and release in stone wool remains the same throughout the product’s lifetime. In the event of unforeseen events such as flooding, the system can also be completely cleaned.

More information about rainwater infiltration

What is Rockflow made of?

Rockflow stone wool elements are made from the raw material basalt and recycled stone wool.

What is a swale?

A swale is a water-permeable buffer that fills up with water in the event of rainfall and discharges it to the ground. A swale is often a ditch or trench with a water-permeable base.

A traditional swale usually consists of a layer of soil with plants. The swale collects the rainwater, and slowly releases it into the ground. But because the space is often limited, a swale must be relatively deep in order to be able to collect sufficient rainwater. A Rockflow infiltration system can be installed beneath the layer of earth and plants, thereby creating more space for the collection of water. Thanks to the stone wool elements, a swale containing Rockflow stone wool is also shallower than the traditional variant.

More information about swales

What is the k-value of Rockflow?

The permeability of the soil is expressed by the k-value, also known as permeability or hydraulic conductivity. A k-value of 1 means that a raindrop travels 1 metre in a 24-hour period. The k-value is an important value, as it maps out the permeability of an infiltration facility.

The k-value of Rockflow stone wool is 50 to 200 metres per 24 hours, depending on the type of stone wool used. The k-value of the Rockflow water management system is therefore comparable to that of coarse sand or fine gravel.

Does stone wool cause irritation?

Although stone wool is a safe material, temporary irritation (itching) may occur when working with it. To minimise this, we recommend that you always take the following measures when working with stone wool products outdoors:

• Wear body-covering clothing (long sleeves and gloves);
• Wear a dust mask and/or safety goggles;
• Rinse off your skin with cold water.

More information about working safely with stone wool

What is the difference between Rockflow and the stone wool used in insulation?

The main difference is that stone wool used for insulation is made to be water-repellent, while a Rockflow element can absorb up to 95% of its volume in water.

More information on the infiltration of rainwater

Is there a CE mark for the material?

There is currently no CE mark for Rockflow stone wool, partly because the combination of stone wool and water management is not yet standardised. Rockflow is expected to have the CE mark and Declaration of Performance in 2023. 

Is it possible to place playground equipment above a Rockflow buffer?

Yes, objects such as playground equipment can be placed above a Rockflow buffer. Please note: the buffer must not be damaged during installation and the forces of the devices must be well distributed over the surface. Please contact the Rockflow team for the specific installation.

How quickly is water distributed in the Rockflow system when it enters the stone wool via the water channels?

The permeability of Rockflow stone wool is approx. 100 m/24 hours. Rockflow systems are always designed so that every system, regardless of its size, is completely filled within 15 minutes.The upstream supply is often the limiting factor rather than the water permeability of the stone wool itself. This principle remains the same for larger systems with multiple input channels.