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Greenroofs? Seems like a bad idea to me.

Discussion in 'Irrigation' started by FIMCO-MEISTER, Mar 3, 2009.


    Messages: 18,668

    saw this article in The Coloradoan.

    i don't care how hardy a plant is on a 110 degree roof it is going to need water. I think a great business opportunity is the green roof removal business.

    Here are the plant choices.

    The green roof will have 4” deep modules randomly planted at 8” on center with the following mix of
    several species of Sedum:
    *Sedum cauticola 'Lidakense' - blue/gray foliage, pink flower, bloom August-Sept, height 4 and 6 inches
    *Sedum floriferum 'Weihenstaphaner Gold' - green foliage, orange/yellow flower, bloom July-
    August, height 4"
    *Sedum hybridum 'Immergrauch' - green foliage, yellow flower, bloom July-August, height 6"
    *Sedum kamtschaticum - green foliage, yellow flower, bloom June-July, height 6"
    *Sedum reflexum - blue foliage, yellow flower, bloom June-July, height 6"
    *Sedum sexangular - green foliage, yellow flower, bloom June-July, height 4"
    *Sedum spurium 'Fuldaglut' - Red foliage, Red flower, bloom Fall, height 6"
    *Sedum ternatum - Dark green foliage, White flower, bloom May-June, height 2"
    These species were chosen by the green roof subcontractor, Green Grid, as selections that are
    well-suited to the Denver climate in terms of drought tolerance and cold hardiness. This selection
    is per the intentions that the green roof be a dry land tapestry that will change its appearance
    seasonally, looking very dormant and lifeless at times.
  2. JeffY

    JeffY LawnSite Senior Member
    Messages: 324

    We have installed some green roofs that are accessible for homeowners to go out and water the plants during extended drought seasons. I think we tend to think of green roofs that go on houses that have steep inclines and inaccessible to supplementing watering if it's needed. Here's an example of a green roof I saw that I wish architects in the US would design.
    That building is in Singapore.
    Another picture of a green roof in Europe, [​IMG]

    In fact, Europe has been in the green roof movement for over 10 years. Tokyo also requires that its medium and large buildings allocate at least 20% of their roofs to be green roof.

    Some people resist change and some people embrace it. I am involved in green roofs because a member of the company I work for is involved in the green movement such as permeable pavers, water-harvesting, green roofs, rain gardens, etc. He initially wanted to use water-harvesting to water an entire yard and I had to shoot that idea done because it was impractical. The tank would run dry after 1 cycle. I convinced him to use the water-harvesting tank to run drip for the landscape beds and know the tank can last for 21 cycles before it needs to be refilled again.

    Messages: 18,668

    Thanks Jeffy. I'll be more open minded in my research. Talking to a well respected commercial roofer it just seems fraught with problems. How do you find a leak if one develops? A roof designed for greenroofing seems doable. Changing an existing roof seems problematic.
  4. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,219

    I've never seen one first hand for a home. But in Snowmass Village they have some condos that have them for the carports.
  5. gusbuster

    gusbuster LawnSite Bronze Member
    Messages: 1,930

    Don't know if you guys have ever heard of the "GAP" Jeans store, but their corporate headquarters here in San Bruno is and was one of the first "green roofs" in this country. Still going strong, been through a few earthquakes, though have not heard of any significant problems. However, the roof is planted with native grasses from our area. The only time though you can see it if you are looking for it and know where to look as you transition from I 280 to I 380.
  6. JeffY

    JeffY LawnSite Senior Member
    Messages: 324

    I agree that retrofitting a roof into a green roof would be complicated and costly. It is easier to incorporate the green roof into a new design. Typically in the greenroof that you shown where they use native plants and water-tolerant plants such as sedum, there is a rubber liner similar to the ones they use for water features and ponds that they lay down on the roof. Just like ponds can have leaks, I'm sure these greenroofs can have leaks as well. I'm not aware how one would discover where the leak is because I have not run into that yet. The greenroofs we install are the modular type where we just lay the trays down and if there was a leak, I'm sure we could just pull the trays up to inspect the liner if it was needed.
  7. mitchgo

    mitchgo LawnSite Silver Member
    Messages: 2,946


    Just put a bunch of Vinca up there it'll do fine.
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,567

    "Green" driveways would make more sense, and be a lot simpler.
  9. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,155

    They are now code in new contruction up north.
  10. EagleLandscape

    EagleLandscape LawnSite Platinum Member
    Male, from Garland, Texas
    Messages: 4,350

    I don't know Peter.

    I don't know how much temp different there really would be if the entire roof was landscaped. You are only talking a few feet, or few hundred feet higher in elevation. Is the solar radiation just that much more intense?

    If the garden is only a little corner of the roof, then yes, temps would be high. if the whole thing is landscaped, i don't think temps would be that big of a deal. There is alot of aeration underneath the materials in a green roof. areas for roots to grow deeper, thus need less water.

    here is a roof top garden in downtown. We do the maintenance on the ground level around the building, not sure who does the roof top though.


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