Why don't you read some of the writings of Pliny and other ancient Romans. They had it pretty well perfected during their time.

Agreed: now if all architects would read same and construct same, we wouldn't have to pay zillions to recapture the past. Although, come to think of it, there probably were't too many high rise buildings then.

Curious,
Roof Soil 'depth ?

Dirt/soil is pretty heavy, especially when wet.

((always been tempted to put row of sprinkler sprays along the roof peaks, just for reducing summer a/c load))

As you are aware, the Green Roof Concept is becoming a world wide movement. Recent projects in Chicago and Toronto have just won major design awards. I assume that you have done a Google Search on the subject and are in touch with the Toronto landscape architectural firms found there who have developed and specialize in the concept. This is not a fly-by-night project and it requires structural engineers, landscape architects, etc.
You are specifically asking for information on the types of plants to grow. This is a difficult question to answer without studying the roof, the ultimate soil depth (usually 4-12"), the wind strength and patterns within the city scape, etc. Many details to consider in such a project. The experts on the subject are in Toronto and I hope you are consulting with them. Sorry not to be more helpful. Good luck with the project.

Thanks for the input. Yes, I have been in touch with the folks in Toronto, and was at the recent press conf. & inormation session at Toronto City Hall, which has a Green Roof on the rounda roof. It is being systematically monitored and information circulated. I also get the newsletters, etc., and we have reams of information, including from the international association. We also realize that diferent depths of soil will host different types of plants.
As for Mikie's comments, the soil used for this type of project is specially formulated for this purpose to be lightweight. Area depth varies from 4" upwards, and I met people from Montreal who were involved in the planning of one site with a soil depth of 14". The roof is designed both to withstand the moisture as well as to prevent the seepage of soil into the roof membrane.
In posing the question, I hoped to spark some interest at GW in the concept which is, as Nandina indicates, a world wide movement, and a really interesting and challenging concept. Also to exchange ideas with anyone who has had experience with Green Roof. The Canadian National Research Council is activley involved in developing sites, with several sites in Toronto and Montreal having developed Green Roofs. Built 20 years ago, my building wasn't constructed with Green Roof in mind, so I don't expect that we will have that depth. I have done a fair amount of research into
plants recommended for varying depths, wind stress, etc. But it would be good to be able to exchange ideas
with gardeners who are actually working on such a project. Even if there isn't a Green Roof in your future, it's a concept which bears looking into.
Eleanorm on the roof in Toronto

The ancient Romans grew salvias because it kept the houses "safe" from evil.

Salvias sounds good: I wonder, too, whether Garlic would do the same?

At least the garlic should keep the vampires away. But how about werewolves?

But I can't see why garlic wouldn't do well, with the proper preparation.

To KAYGARDENER -- I just tuned in after a long absence, and thank you for your input. I'll check it out.
We are in the process of hiring design consultants to
help us develop roof design, etc., and it's a very exciting project. A few weeks ago there was a program on the Discovery Channel, showing how Ford Motor Co., in Dearborn Mich. is not only re-claiming "brown land" with the use of native plants, but is also installing greenroof
on its entire plant -- the larges greenroof in the world!
It's such an exciting concept, very accepted in Europe, but almost unknown in N.A.
Thanks -- Eleanorm on the roof deck inToronto

Look for sources in norway or sweden. Green roofing is the way they traditionally built for thousands of years. Back to the Vikings. You still see many sod roofed houses around. Very pretty as well as being functional. Think about keeping a house warm in the cold Norwegian winter.

NA is only slowly catching on to what has been an accepted way of roofing in many parts of the world.
Switzerland has passed legislation that makes it
incumbent on builders to install greenroofs, and also
support retro-fitting older buildings in this way. Sooner
or later we will wake up to the advantages =-- keeping
houses both warm in winter and cooler in summer,
reducing the amount of run off rainwater, alleviating
the heat island effect in cities, etc. Also, greenroofs last
much longer than standard roofs, because of the protection they provide for the roof membrane. One can
only hope that people this side of the water start looking into this type of roof.

Man, I wish my condo weren't filled by dunderheads. I'd like nothing more than to do a greenroof, but the other owners fear nature and anything connected with it and fight it tooth and nail.

I hope you get yours working.

I saw my first green roof at the 2002 Philly Flower show and fell in love with the whole idea. The exhibit was created by Temple University Ambler Landscape Architecture and Horticulture students and you can get in touch with the school and dept from the link below.

Good luck
Springcherry

Here is a link that might be useful: Temple University Ambler

Just wandering around GW, and came upon this thread. My husband and I have decided to do this when/if we build a house. There is a restaurant in town here that has planted along the outside edges of the roof. It looks wonderful and has mostly herbs and some evergreens (junipers, etc). Here's a link: http://www.carrabbas.com/company_articles.asp
There are a few articles and some pics. It's really a great idea. Even if it is not for the energy/space conservation, but purely for asthetic reasons. If you go ahead with this, I'd love to see pics!

Thanks,

Shelly

A couple of links:
http://www.greengridroofs.com/
http://www.cityfarmer.org/GreenRoof.html
http://www.roofmeadow.com/

I'm just tuning back in, after a long absence due to family issues, etc. Just wanted to report that our GreenRoof project is progressing well. Design specs
have been completed and passed by membership, who are very enthusiastic. Binki, if y ou read this, I suggest that you show photos of some of the exciting
roofs that have been developed in NA -- our members
went through the whole range of "ooooh" and "aaaaah"
when we showed photos of the possible.
Our design for the community garden area will have many planting areas, plus a gazebo, pergola, waterfall,
dry stream bed and individual "shelters" to accomodate
picnic tables and benches. Underneath it all, a water reservoir which will hold rain water to be used to water
plants, and will also lessen the amount of run-off water.
This is becoming a problem in some cities, because of the cost of re-cycling water.
Right now we are in the process of raising funds for the project. There is money in our roof reserve for roof replacement, after 22 years, but the GreenRoof is more costly. However, considering that this type of roof has a much longer life span, it will be worth it . But, since we will be including a major component of solar energy recovery, we won't have any problems with that part of the project. Members are eager enough so that they are going to take part in internal fundraising, the concept of "ownership" being something I'm working on.
there are more public buildings going in this direction:
when you see photos of the "heat island effect" of flat
roofs in large cities, you begin to understand why this
is a concept that really does need to grow and gather support.

Please keep us posted. What do you mean by "major component of solar energy recovery"?

What a fascinating discussion. I have seen articles in garden magazines about this, but I thought it was used just for decorative out-buildings.
In light of the fire devastation of homes in CA recently, do these roofs provide any additional fire protection?

Odd that this is a catching on now, in Detroit they've been doing this for years, of course unintentionally.

http://www.freep.com/news/locway/journ15_20010515.htm

I think the sedums had enough water in them to foil sparks that might otherwise start a fire; this was important in a world heated by wood fires.
so, try sedums. They also use very little soil.

I've been away for quite a while, but still working on the GreenRoof project. By "major component of solar energy recovery, " I mean that the inaccessible north roof of our building will have solar panels, in addition to the extensive planting areas, which will use sedums.
The energy recovery will be used to heat the water for the building.
As for the question about fire protection, and the depth of soil, soil depth on GreenRoofs varies, depending on how the roof is engineered to withstand the weight. First thing we did was to hire architects who
did all the preliminary research on structural aspects -
weight bearing, sun, wind, water recovery and recycling -- all the things which will impact on the new roof concept, and on the final design, which we now have. Some of our "extensive" planting beds on the south roof will be 12" deep, but the sedums on the north roof will only need 3" of soil.
GreenRoofs are definitely not new, and some European countries have laws making it mandatory to install this type of roof on new buildings. There are some beautiful park-like roofs in the U.S. which are accssible by people: there are also GreenRoofs which are used solely to minimize heat loss and preserve cooling in buildings, such as the largest such roof in the world, on the Ford Motor Company plant in Dearborn, Mich. This is concept whch is being promoted to lessen the impact of smog in ciies, by generation of oxygen, and reducing the amount of CO2
emissions by minimizing the use of heating fuels.
minimize the "heat island" effect in cities in order to
on the Ford Motor Company plant in Dearborn, Mich.

There are some down sides to green roof gardening. The main one is that it's expensive to build strong enough to support the extra weight. It's expensive to repair leaks in your roof, should they occur. Generally, a "flat" roof is prone to leaks, and that is exactly the basic design of a "green roof. Somewhat mitigating all this is this: it's the sun that degrades a roof. By a protective layer of soil and plants, the roof stays cooler, and is not exposed to uv, so the waterproofing lasts longer. However, ordinary frame construction may not be adequate. Most of the below-ground green-roof houses are made from concrete. Usually they're on a hill-side so that they can have an exposed wall with light on the "living" side of the house, and bedrooms on the "cave" part of the house.

It also occurs to me that a thatch roof, is in some ways, a "green" roof. Thatch supports some small plants, when it's old, I believe. Perhaps not a "healthy" thatch, but I've seen photos of some thatch roofs that had growth.

Then there's the concept that many of us, who choose light colored roofs in the south to maximize reflection, also end up with green roofs from algea and moss, if we are in a humid environment.

I suppose if you consider the saving in heating and cooling over the life of the building, a green roof may be cost effective. However, most people can't afford the initial investment. Perhaps if more people bought them, they wouldn't be so expensive to build.

There's no doubt that a greenroof properly engineered is an expensive proposition, which is why we are probably looking at doing the whole job in increments.
Since our building's roof has definitely reached the end of its usefulness, we are looking at doing the initial phase from building structure up, while building in the potential for the actual garden plan we have agreed upon. The soil and water reservoirs will protect the
roof, lessening the solar impact, as you pointed out.
We would be able to do some planting at this stage, and do the rest of the plan as funds allow. Having been through several (costly) stages of structural engineering, we are very confident that the building itself will support the entire completed project. It's something to look forward to.

There is no question that a greenroof can be expensive and heavy but they certainly don't have to be. The research being done by Dr. Karen Liu shows that heat stress on the membrane ( waterproofng) is minimized by covering it with a vegetated layer. This adds to the biomass required for carbon sinking and helps with the Urban heat island. Storm water retention on greenroofs can be up to 90% and there are many environmental and social benefits that are hard to quantify. I think you will see the cost of green roofing come down as products are developed with the residential and industrial markets in mind.
Rooftop Gardening such as Eleanorm is doing is always going to be more maintenace, weight and cost but has a great effect on residents and could become the new Urban farm, thereby limiting travel miles on produce and allowing for organic veggies to be grown closer to their ddestination.
When you get your garden up will you be adding pictures to your webpage?

Eleanorm, we're also starting our green roof in Toronto. For me, it's not so much a roof alteration as a garden expansion.... I'd say "cheap at any price" if I could afford to think like that!

At this time next year I'll have carrots growing over my head. Skygardener, if that's not a hard-to-quantify benefit I don't know what is ;-)

Lyrical-- So gladt o hear that you're also going the greenroof way. It is, as you say, cheap at any price, although the price is pretty high. We have got a really good grant for phase 1 of the project, and should be starting the deconstruction of our roof deck garden by the end of september. Our total area is more than 12,000 square feet, with three separate areas to do, so it's going to be a large project. Our design for the accessible area includes a gazebo, waterfall, dry stream bed, and various planting areas, with a run off water reservoir under the whole thing. Plus solar power recovery system on one part --the non-accessible one.
. I'm really excited by he whole thing, but a bit overwhelmed by the cost and fund raising projects.
When do you start your project, and what are the plans? Besides having carrots growing over your head.

We have a green roof on our solar home and regret it for many of the reasons mentioned above. Expense--My husband is an engineer and we had to install steel trusses in the living room to hold the weight of the wet earth load. Not only money, but do you want steel trusses in your living room? Also, our house is solar, so we wanted a rather steep roof, for maximum south face. So we have a rather steep roof with sod. A flat roof is a leaking problem and also is not a good design for solar. Also, the maintenance on a roof is difficult and time consuming. Have you thought about how you'll mow it? Weed it?

Debb-- Thanks for sharing your experiences, but I think our green roof is going to be quite different from your situation. For one thing, the garden part of the south roof will have barrier free walkways between the planting beds, so there won't be a question about weeding or mowing. This part of the roof will be laid out as a true garden, with beds, a water feature, and gazebo. We are planning on using some native grasses for the planting, plus te perennials presently up there.
The north roof, which is not accessible, will also be laid out in beds, with either low growing sedums or native grasses-- no weeding or mowing involved.
Before even considering going on with the project, we had extensive engineering studies done on our building, using both original drawings and subsequent studies, so we know where the weight bearing walls are, and the pertinent facts about the roof structure. I have no worry or fear about having to have steel trusses in my living room, and I live directly under the roof.
I wonder also about your comments about the weight of soil on your roof. Most contemporary greenroofs use a lightweight soil,and there are many good examples of building with quite deep plantings which have not caused weight stress. For 20 years we have been gardening up on the roof deck(8th floor) in large barrels filled with soil which I "make" from compost + peat +
perlite, and even though the barrels (60of them) are
arranged in clusters, they have never caused any weight problems in the apartments below.
Expense is a consideration, and in addition to funds from our roof reserve we are doing some fundraising. We just received a grant from the Ontario Trillium Foundation, which would not have given the money if they had any doubts about the feasibility of the concept.
Believe me, we had to provide a lot of factual information before they even considered our request.
So, we go on with the project, and are now in the second phase of the project.
Thanks for sharing your concerns, and good luck with sorting out the problems you are having.

We're currently planning a greenroof project on a private property - it will cover 2000 square feet and intial estimates suggest it will cost US$25/sf which includes everything, materials and labor, from hot-poured membrane through all the layers, even including soil and plants. It is the roof of a 1-story parking garage and will get pretty active use because the back (kitchen) door of our 2nd story loft apartment opens onto it. We are waiting for a design estimate from a landscape architect. It is a luxury treat as well as an environmental benefit. I'd be happy to share before (and, hopefully, after) pictures if you're interested.

Nicky bklyn -- I have been away for some time, just chec ked i n, and was happy to hear of your project. Presumably by this time it's well under way, and I for one would be happy to see photos.
Our project is still moving along, but slowly, due to having to check out legal issues, etc. But the work is out for tender now, so we will have a new roof by Fall. Because of the size of the project --
24,000 sq.ft., it will be done incrementally, so I don't expect that all of the bells & whistles will be in place this year. And there's still
a lot of fund raisingk since the total cost is very high.
Please post photos, and I'd really like to hear h ow your project progresses. You can always contact me directly.
Eleanorm on the roof deck in Toronto

Nicky bklyn , I would love to see before and after photos of your green roof. Could you please send me the photos?
pinguva@gmail.com