Our annual end-of-summer contest is here, come on down to the Dave's Garden County Fair!

Do you have green roofs in your city?

Josephine, Arlington, TX(Zone 8a)

The city of Austin Texas has some of those, a Starbucks coffee shop there has one and I think it is a wonderful idea.
What do you think?

Lincoln, United Kingdom(Zone 8a)

I'm interested to hear more about what type of 'green' roof you are talking about frostweed!

Is it environmentally 'green' because of the materials used, or one of those where they actually grow plants on the roof?

Sultan, WA(Zone 8a)

My neighbors roof it green. Green sheet metal. Lasting longer that my asphalt roof so far.

Josephine, Arlington, TX(Zone 8a)

They are actually growing native grasses, but many kinds of plants could be grown.
Reminds me of the old pioneer cabin roofs which were made of sod that was thick enough for the grass to grow and it kept the cabin cool. I believe that is the same principle they are using now, but with more modern materials of course.

Josephine, Arlington, TX(Zone 8a)

I found this link to the Wildflower Center explaining green roofs.

Lincoln, United Kingdom(Zone 8a)

Interesting link frostweed!

I guess it depends where you are and how you need to adjust to the climate. The depth for a large strucure can be up to 15 feet, some houses here have been built underground with a front covered in glass, a hill on top provides insulation and roof lights to the surface provide extra light.

I imagine in a hot climate a green roof would insulate from the heat as opposed to the cold but it does that too, soil is slow to warm as well as lose heat and the depth would make a big difference. It would also require a strong structure to hold it.

I have seen on gardening programmes sheds being planted with succulents on the roof, they don't need much soil and can survive some dryness.

Ida, MI

Timber Press has an excellent book out on this, the title is "Planting Green Roofs And Living Walls". It is an excellent book. It gives a complete description of the process, the materials involved and lots of examples of finished projects. This is very popular in Europe, as usual the US is slower to catch on to green ideas because we don't HAVE to. I don't mean legal wise, I mean we still have much more available land etc. The environmental pressure is not as great here as in Europe. But there have been some large projects done here and interest is building. Construction involves a water proof membrane tooped by a root barrier to prtect it. On top of that is 4"-6" of soil and of course the supports have to engineered to carry the weight. Plants are carefully chosen and the book talks a great deal about appropriate plant material. The benifits are many, particularly decreased storm runoff. Storm runoff is a huge problem for cities. Even in the small city where I worked the wastewater guys went crazy whenever a good rain came in. Previous building practices were geared to getting the water off of the roof and down stormdrains quickly. Well most stormdrains are connected to the wastewater treatment plants. Many wastewater treatment plants are old and at or above capicity now so when stormwater floods the system often untreated sewage has to be released to keep up. Another benifit is hugely reduced heating and cooling costs. Then add to that a correctly installed green roof will last about twice as long as traditional and the fact that greenroofs are proven to provide habitat for insects and birds and even some small mamals greatly reducing the environmental impact of a building and green roofs make sense in a big way. Timber Press has also come out with a book or is about to, on just the plant choices for green roofs, can't remember the name of it off hand but is next on must by list. By the way, I love the idea for this forum, sustainable alternatives has long been an interest of mine, nice to know other gardeners are also thinking in this direction.

KC Metro area, MO(Zone 6a)

I am loving this too. It will allow me to hear pratical ideas for green living. Sometimes the little things can make a huge impact.

Lincoln, United Kingdom(Zone 8a)

We have the same problem here with floods and sewage overspill, although I'm not connected to mains sewers.

I think the green rooves may be cost prohibitive for many, it's the people who want to build their own special residence, and usually those who can drum up the money or already have it that build these houses. There are strict building regulations here too and many of the designs can hit red tape, besides being able to find the land to build on at an affordable price. There is an eco village here where all the houses are built to use the power of the sun for heating, along with other eco friendly ideas. Some people have solar panels fitted to their rooves, my neighbour has some which are probably outdated now, there are systems which are supposed to be able to harness the sun's rays even if there is cloud, I can't see they would be very effective with the amount of sun we get at times but can supplement existing systems. They now can cost around 12.000, nearly double in $'s.

No. San Diego Co., CA(Zone 10b)

Saw one of these installed on Paul James's Gardening by the Yard (HGTV). We have to have a tiled roof because of fire danger, but I'd love a shed with a green roof. Put it on the list, love. :-)

Sultan, WA(Zone 8a)

Does moss growing on your roof count? My neighbor actually had some weeds growing out of the moss, growing on his roof (not the one with the sheet metal roof). I love my neighborhood!

Succulents on a shed roof sound like a wonderful idea!

Ida, MI

I just had to get out my book "Planting Green Roofs And Living Walls" after getting into this thread. Seems the movement started in Germany and Germany is still leading the way. Some examples in the US.
Chicago City Hall
Peggy NoteBaert Nature Museum, Chicago
Ford Motor Co. Complex, Dearborn, Michigan This one is not far from me, I have never seen it, but I'm going to make a point of it.
I think Portland, Oregon City Hall Also

Here is a link to a site on the Chicago City hall green roof with photos and articles.

I will try to post some more examples later.

Lincoln, United Kingdom(Zone 8a)

That's some roof, I would feel safer if there was a railing around the edge!

I decided to search around, see what I could find. Amazing what is going on under our noses!


So.App.Mtns., United States(Zone 5b)

Yep. Google shows over a million pages if you search "rooftop gardens"!

Theoretically, any roof surface can be greened - even sloped or curved roofs can support a layer of sod or wildflowers. Switzerland has just passed a bylaw which states that new buildings must be designed to relocate the green space covered by the building's footprint to their roofs - even existing buildings -including historical buildings - must now green 20% of their rooftops. This has created an increased demand for research and material/product design, which will soon be available to North American markets.

Josephine, Arlington, TX(Zone 8a)

All of those are absolutely great!!!

Lincoln, United Kingdom(Zone 8a)

I think the old style farm houses were covered with soil and grass being built into a hillside, but trying to do even 20% of historic buildings could be a headache for many. I found a pic of some Swiis rooftops, and wonder how this would be impemented.


See how steep they are, I can foresee more problems than benefits,


Lewiston, CA(Zone 7b)

The new library in Redding CA. has a green roof. Probably the first in the area.
I think the idea of building in the earth is good. Unfortunately on our property we have numerous springs & it would been an engnerring feat to just deal with all the water. An aquatic center maybe! LOL

Josephine, Arlington, TX(Zone 8a)

Interesting article about pioneer sod houses with green roofs, quite different from what they are doing today.

Gent, Belgium(Zone 8a)

very interesting thread !!!
I would really love a green roof!!!
Imagine how much more livable a town would be with all green roofs and all the houses having climbing plants!!
But like Wallaby says steep roofs might be a challenge which is hard to overcome.
And sadly mine is very steep and it would also be out of the reach of my budget.

Lincoln, United Kingdom(Zone 8a)

More of a case of old methods with a modern application, those sod houses must have been a nightmare, apart from all the other hardships people had to face.

bonitin it does sound a good idea if it could work, I think there would have to be government help if they really want people to do it, then there would be maintenance which again could be expensive. As the woman said in the article on pioneer sod houses, "life is too short to be spent under a sod roof".

Green rooves would help a great deal in atmospheric pollution as well as reducing heat, but the plants would have to be tolerant of that. This idea needs a lot of forethought, and as we too often see good ideas are put into practice to find further down the road problems that were not foreseen. An example of that here is the mini roundabouts the councils put in at every little junction in villages, many drivers on the main route thought they had right of way, they just couldn't comprehend that it WAS a give way roundabout, besides they often made manouvering around them difficult because the road was too narrow and you could easily hit the kerb on the exit side. There were MORE accidents, not less. Guess what, they took them all out again! See my point.

Ida, MI

Green roofs are actually not new, if I'm not mistaken they have been around since the 50's in Germany. Lots has been done to work out the bugs. Several governments in Europe and municipalities in the US have the right idea, they offer benefits for green roof construction. For example, say a developer wants to construct condos on a given location. There are limits everywhere as to how much of the land can be covered with buildings. Well, if the developer incorperates green roofs he can extend the amount of sq. footage he can build on a given peice of property, thereby increasing his profit potential. Some other large cities with storm water runoff problems are taking a harder line and demanding that something must be done to limit stormwater runoff, green roofs are an attractive option.

There are ways of constructing green roofs on steep slopes, but it is more involved. In short, it is easier to incorporate green roofs in new construction that is designed to be green from the get go so there is lots more being done from that angle than retrofitting older roofs though this is already being done. Green roofs of taday are far superior from the old sod roofs, even superior to present day roofing materials and there are companies springing up to meet the design challenges and material requirements. Thewaterproof membranes, root barrier, and drainage layer requirements have attracted companies filling the void. A modern green roof utilizes lots of modern technology, it is considered an attractive option, unlike sod roofs whichwere simply the only material available at the time.
Modern green are designed to be long lasting, trouble free and require minimal maintanace, surpasing present roofing materials. You will be seeing more and more of them, its an advancement of technology, not a setback. If you installed a green roof on your home today, it is designed so that you can live in that house the rest of your life, enjoy the insulation benefits, (which can be huge especially in warmer areas), have less problems with runoff and less maint., and never need a new one. Quite an attractive option.

This message was edited Mar 3, 2007 10:12 AM

So.App.Mtns., United States(Zone 5b)

I have a small building used as a root cellar, and the back half is cut into the hillside. I think I may play around with burying more of it and adding a green roof. I won't have to worry much about roof leakage, unlike a habited house, but it's an opportunity to see what's possible.

Ida, MI

Darius, get yourself a copy of "constructing Green Roofs And Living Walls", it has a good explanation of the engineering involved and you could adapt this to using found or scrap materials. For example, check Farmtech Growers supply, they sell remnants of pond liners that would be fit the bill for your waterproof membrane. There is also a discussion of suitable plants and depths necessary for each. Using this option on a root cellar is a prime application of this method.

So.App.Mtns., United States(Zone 5b)

Thanks, I added it to my Wish List at Amazon.

I was thinking of exploring bentonite as a waterproofing material. It is used a lot as pond liners as an alternative to the more expensive synthetic membranes.

How's this for a green roof? Photo is the jacket cover for a book, and not my photo.

Thumbnail by darius
Ida, MI

Beautifull! I would love to have a buiding like that! What is bentonite? If the area of your roof is not large those pond liner scraps are really cheap, I was very suprised.

So.App.Mtns., United States(Zone 5b)

Bentonite is a clay.

Ida, MI

Oh, if you have it available you cant get any cheaper than that!

Greensboro, NC(Zone 7a)

There's an Italian restaurant here that has their roof landscaped. I like it although I wasn't thrilled with their food:LOL: It seems to be mainly grasses and evergreen shrubs with a few taller evergreens for accents. I guess it sort of has a slightly mediterranean feel to it, coastal though, think of beach grasses.

I wouldn't mind seeing more of this around.

So.App.Mtns., United States(Zone 5b)

spot, I'm told you can buy it in sheets like sheetrock. If you go to Wickipeda, they give a decent explanation.

A friend in Boone years ago used bentonite on the outside of a curved block foundation wall in an earth-sheltered house.

Josephine, Arlington, TX(Zone 8a)

Wow! this thread is getting more and more exciting!!!

KC Metro area, MO(Zone 6a)

Yes it is!! i'm loving it!!

Ida, MI

Thanks Darius, great link on the bentonite. Dont forget you will need a root barrier or I would imagine the bentonite would be highly susceptable to being permiated by the roots. One other consideration is weight. I would imagine the bentonite would be quite heavy especially when wet, make sure your support can withstand it. From what the wikipedia article stated it looks like bentonite is used mostly in at or below ground applications, the weight factor could be the reason. While using the rubber pond liners may not be as "green" if you use the remnants, at least you know you are keeping something out of the landfill. Drainage and root barrier layers are open to lots of found materials I would think. Drainage for example might be provided by cast of corrugated polycarbonate panels, if you are using only small plants on your green roof this might be enogh to be an effective root barrier as well. Now you have me looking at my old chicken coop considering the green rood possibilities! LOL

West Pottsgrove, PA(Zone 6b)

Here's an article in today's paper about a Philly mayoral candidate who's planning lots of green roofs and more trees. He has a good chance at being elected, right now he's a US congressman:


edited to add I just noticed the article says Chicago added 2 million square feet of grass rooftops in two years!

This message was edited Mar 5, 2007 3:43 PM

Helena, MT(Zone 4b)

Spot, since your book is about roofs and walls, how would you make a green wall? Are they mainly talking about growing vines up and down the wall?

Ida, MI

Yes, the living walls are mainly vines. there is a lot of info. about the energy savings especially in the warmer ares. For large areas and big buildings they use a wire grid with spacers to keep it away from the wall.

West Pottsgrove, PA(Zone 6b)

Check this thread out, it's about living walls with water. One of the better threads lately, and there's a newer one on the same subject in the Tropicals forum.


Ida, MI

Wow that is cool! You could use that system to grow veggies hydroponicly too I bet!

Lakeland, FL(Zone 9b)

We have a lot of Green roofs in Tampa where people grow plants up there i have a freind she does all her veggies on a flat roof in tampa i think you can find a lot in miami to

Philadelphia, PA

I got into green roofs after reading all the statistics on energy savings and prevention of flash-flooding at www.hapcity.com/greenLiving/pages/greenRooftop.jsf . Btw, the part of the roof that I'm planning on greening is on top of the 2nd floor, next to a partial 3rd floor, so I'm definitely thinking about planting veggies there ;-).I'll have really good access to it and I'm even planning maybe on taking out the window I installed that goes into that part of the roof and replacing it with a small glass door instead (crawling out of the window is a bit painful..).

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