I see you list the UK as home. I've only seen one green roof locally - and only as up close and personal as you can get simply driving by. Seemed to be largely mosses on a garage with a fairly low pitched roof.

An extensive green roof has low lying plants designed to provide maximum groundcover, water retention, erosion resistance, and respirative transpiration of moisture. Extensive green roofs usually use plants with foliage from 2 to 6 inches and from 2 to 4 inches of soil.

An intensive green roof is intended to be more of a natural landscape installed on a rooftop. Intensive green roofs may use plants with foliage from 1 to 15 feet and may require several feet of soil depth.

The first step, for either existing dwellings or new construction, should be to consult with a structural engineer to determine the structural requirements of a green roof.

Thank you very much! Dose that mean both extensive and intensive green roof are difficult to be managed? I think the irrigation and drainage are big problems.

I have no expertise in the field or have any knowledge in the hard facts of roof gardening. The biggest situations I see, as practical matters, are the structure has to be able to bear the additional weight load, and some kind of barrier has to be in place to keep soil and moisture from damaging the average house/structure roof itself.

There's quite a bit of information on the internet on green roofs. The cities of Chicago, IL., (Google Green roofing in Chicago and you'll get some listings with pictures of skyscraper roof gardens) and Toronto, Canada, are pretty much leading the way here in North America.

My new employer plants up modules for a large green roof distributor in the area and I interviewed to be green roof sales rep for another before accepting my current position, so I have a passing familiarity with the modular system of extensive green or living roofs.

As DinB indicates, the first consideration is the structual integrity of the building utilizing the roof system as well as waterproofing. Once these factors are adequately addressed, the system is easily installed and requires minimal maintenance. Plants most often utilized for modular systems tend to be low growing and spreading sedums and succulents and a few similar habit groundcovers. Supplemental irrigation after installation, at least in my climate, is generally unnecessary.

One of the biggest draws of these roof systems is the local (and perhaps more widespread) trend toward "green" construction methods overall. Utilizing green roof systems offer considerable insulation factors, reduction of runoff and storm water issues, reduces the carbon footprint, generates urban heat island mititgation and can provide for considerable tax credits/economic benefits in the form of LEEDS certification. They are certainly rapidly becoming one of the sustainable construction/landscaping waves of the future.

Here is a link that might be useful: Live Roofs

I recently talked to a salesperson for a green roof system, and ended up quizzing him quite extensively. One thing I thought was interesting was that he said that the urban heat island mitigation effect was the same as having a white roof - which is already required in Chicago, fwiw. Their system used various types of sedums. As for maintenance, it sounded like weekly weeding was the biggest chore - because if you get tree seedlings on your roof, the roots can break through the roofing, and you can get leaks. So, you definitely have to have a building owner committed to the costs of having someone weed the roof every week (or going up themself to do it, of course).

As for draining, iirc, he said that the roof could absorb about an inch of rain at one time - but after that, you have to have regular roof drainage. So, it helps - but not so much in the huge rains that cause flooding, so you still need detention.

Also, apparently you can't walk on the green roof like a lawn - you have to have pathways to any sort of mechanical unit, and if you want people to be up on the roof enjoying the greenery, you need a terrace or whatever for the people.

So, I think they are interesting, but I haven't yet had an appropriate project for one.

I know a bit late on the conversation, Personally I think people get into over designing these systems.We have a green roof, I designed it to be able to withstand people and animals walking across it.It been in since 05, and has children running across it, wildlife of all types including deer on a constant basis.We chose to not use any of the available systems and did our own thing which was cheaper, used local materials, added more insulation value.
Our home can be seen at the Natural home mag site, the story line good neighbors.

Our home listed above with its green roof will air on the Green Discovery channel on Nov 14 08 at 6pm eastern under the name the Happy house, if anyone would like to see our green roof.
M

I took the liberty of locating the article in Natural Home. Kudos, Mary, to both of you. Hopefully can watch the show on Green Discovery channel.

Rosie

Here is a link that might be useful: Natural Home magazine article

{{gwi:15502}}

Here is a link that might be useful: my some ideas

Hi all, sorry for coming a bit late to this thread, but I have an article up on my site about the best sedums for green roof planting in various climate zones. Hope it's helpful, and I will be busy trying to create ideashare's concept on my own roof :)

all best
DAve

Here is a link that might be useful: green roof sedums