Here are some questions that engineers commonly ask us about NEDLAW Living Roofs™:

Is the growing medium essentially topsoil?

Are living roofs more susceptible to leaks or breakdown of the membrane?

Is a new roof membrane required before an installation?

What types of roof decks can you install a living roof on?

What is the weight load of a NEDLAW Living Roofs system?

What is the R value of the system?

Can a living roof system be applied towards LEED designation? If so, what points can be rewarded for a NEDLAW system?

Is the growing medium essentially topsoil?
No, the growing medium is a specially formulated light-weight mix designed for high water-retention capacity and a low density. Once in contact with moisture, the growing medium’s binding agents are activated to prevent soil loss due to wind and water erosion.

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Are living roofs more susceptible to leaks or breakdown of the membrane?
No. In fact, properly constructed NEDLAW Living Roofs will extend the lifespan of your roof membrane, often by 30 to 50 years.

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Is a new roof membrane required before an installation?
It’s very important to verify the integrity of the membrane before installing a living roof. If the membrane is still in good condition and is at less than half its expected lifespan, the membrane will not need to be replaced. However, if the membrane is in poor condition or over half its expected lifespan, the membrane should be replaced.

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What types of roof decks can you install a Living Roof on?
NEDLAW Living Roofs systems have been built on steel, concrete and wooden roof decks.

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What is the weight load of a NEDLAW Living Roofs system?
Weight load can vary significantly depending on the soil depth used. Our sedum living-roof system requires as little as one to two inches of growing medium or as much as four inches. Accordingly, weight can vary from ten to twenty pounds per square foot. Our Native Meadow Living Roof system requires four to six inches of growing medium for a weight load of between twenty to thirty pounds per square foot.

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What is the R value of the system?
The R value of our Living Roofs range from twenty to fifty, depending on the depth of growing medium.

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Can a living-roof system be applied towards LEED designation? If so, what points can be rewarded for a NEDLAW system?
Yes, the installation of a NEDLAW Living Roofs system can be applied towards LEED designation, and will play a role in the following points:

Sustainable Sites:
SS 6.1: Storm-water Management – Rate & Quantity
SS 7.2: Heat Island Effect: Roof

Water Efficiency:
WE 1.1: Water Efficient Landscaping: Reduce by 50 %
WE 1.2: No Potable Water Use or No Irrigation

Energy & Atmosphere
EA 1.1: Optimize Energy Performance

Materials & Resources:
MR 4.1 & 4.2: Must contain 7.5 % to 15 % recycled content
MR 5.1 & 5.2: Must consist of 10 % to 20 % regional materials

Innovation & Design Process:
ID 1.1: Innovation in Design

For more information, visit Canadian Green Building Council: CAGBC

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