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Roof Misconceptions: Do Green Roofs Often Leak?

 
Question:

Herbert asks: Our company is looking at building a new plant. I have always like the idea of a green roof. We are big in trying to be green.The owner of our company's daughter is trying to get us to go green in every way we can. Our company is based in Germany. I suggested the idea of a green roof, for looks and energy purposes. The question that came is, Is there problems with leaking. The building we have now has lots of leaks. We are not moving because of this,we out grew the building. Where would I find more out about the green roof. Are there any green roofs close to Carroll County? We are moving fairly fast on a site and to have plans for the new building.

Answer:
Advice provided by: Rob Freeman Jr, LEED AP, Green-Buildings.com
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Hi Herbert,

Thank you for your question.

Typically, a green roof does not cause any leaking. The leaks you are seeing now are due to tears or punctures in the waterproof membrane currently on your roof. These may be caused by the roof’s natural expansion and contraction due to temperature fluctuations, or by foreign object damage.

A green roof should, when installed properly, actually protect you from both of these hazards. The insulation provided by a green roof keeps the temperature of the roofing membrane more constant, which reduces cracks from expansion/contraction. The layer of soil and plants protects the membrane from foreign object damage. A green roof also protects the membrane from UV damage which can weaken it in the long run and lead to more leaks.

Ideally, a green roof would be installed on a new roofing membrane so you could be sure it was being installed on a roof with no existing leaks. If this is done, a roof membrane under a green roof will last 2-3 times longer than a roof membrane exposed to the elements. In some cases, minor leaks can be located, repaired, and the green roof put in on top.

To sum it up, a green roof should actually help a roof to leak less, if at all. In response to your question about green roofs near you, Baltimore has quite a few green roofs including one on the Hilton downtown near the Convention Center.

For objective information on green roofs and to learn about common misconceptions with their technology, Green-Buildings.com will be hosting a free Webinar with Amy Norquist, CEO of Greensulate on May 5th, 2011. The webinar will cover the five biggest mistakes to avoid when installing a green roof.

The webinar should cover all the basics on the process. FWIW, two Greensulate employees are actually from Harford County, MD and keep a close watch on the green roofing progress in the area. They would be helpful to ask about green roofs in the area.

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Expert Advice and Comments

green roof waterproofing

Thu, 03/24/2011 - 12:05 — dave hilary (not verified)

Yes, it is a common misconception that green roofs are more prone to leakage when installed correctly. Another issue is the selection of the root barrier material, as sometimes roots can penetrate the barrier and cause leakage. I have an article about installing green roof waterproofing materials up on my site, which might be interesting. Here's the link:

http://www.greenroofplan.com/waterproofing-your-green-roof/

Green Roof

Tue, 05/17/2011 - 23:25 — gerald88 (not verified)

Totally like this blog. Thanks for the informative sharing and appreciate it.
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Solar energy, Lightweight Steel truss, Metal decking supplier, Green building roofs, Roof Purlins, Solar PV system Provider, Steel wall framings, sustainable energy roof solutions

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