Personally I’ve never been a big fan of turf roofs. Perhaps this is because they look out of character, if more of them were to appear they’d be more in character and perhaps I’d develop a soft spot for them. It was the same when cars went from being angular to being rounded. In the UK it was the Ford Sierra that was the first popular curved design, to start with it looked really odd and earned the nickname of “the jellymould” but then everything else followed suit and it’s now the angular designs that look out of place.
There is a lot to be said for turf roofs, there’s the points you mentioned but they’re also reduce energy consumption and bills, they last longer than conventional roofs, are cheaper to maintain, provide better sound and noise insulation, don’t use raw materials, improve air quality and provide a garden area if so desired. And… you can put them on pitches of up to 30°, not just flat roofs. Here’s an award winning project on the Isle of Skye that has a pitched roof:
http://www.ruraldesign.co.uk/Kendram-Tur...
It would be nice to see more of them and I think they’d help brighten up some otherwise rather drab streets and properties. They are becoming more common so perhaps in the years to come they will be a common sight.
EDIT: Just to add, on new-builds there is little difference in price, the extra cost of sturdier roof members is offset by savings on slates, tiles, ridges, flashings etc. A DIY retrofit would cost about ￡15,000 / $25,000 on an average house, double if contractors did the work but if the roof is due for replacement or overhaul anyway then the costs will be significantly less.
Credit to my partner for providing 90% of the info, she’s an architect and has done a couple of green roof projects in recent years.
I think it's one of those things that only works in certain areas.
In a lot of cold areas, roofs are pitched for a reason--so the building doesn't collapse from snow buildup. In those areas, a sod roof would rarely be a good idea, both because the roof needs to be pitched to deal with snow, and because the sod would be dead all winter.
And somewhere like where I live, snow isn't really a concern, but water is. It's far too arid in most deserts for roof turf to be either economically viable or particularly sane. You'd need to pour a *lot* of water onto the roof to keep the grass alive, and it would be better to use that water for other things, like growing crops.
But, in tropical to relatively mild temperate areas with adequate rainfall, turf roofs are a great idea. You could even keep some rabbits on the grass to raise meat and keep maintenance a bit lower (no mowing).
Not necessarily turf (ok, at least not outside the UK ;-) ), but so-called extensive green roofs. Depending on the substrate you use, there are possibilities for basically all kinds of roofs to be retrofitted. Designing it in from the start is definitely the better option.
However, in some areas, there are building regulations that won't permit that :-( .
I don't think those downplaying this idea have really thought about it and have not looked into current building architecture. Green roofs are a reality. The area in which I live there are actually many buildings in the area that have green roofs. And some of these green roofs also include trees and plants. There has even been a building in the planning stages in Milan Italy that consists of a vertical forest.
http://travel.yahoo.com/blogs/compass/ve...
The largest green roof in the world is on top of the Vancouver Convention Centre and it consists of a thriving ecosystem including 4 beehives.
http://www.vancouverconventioncentre.com...
While many in here are correct that a lot of current buildings can not take the added load of green roofing you can update many of them to include irrigation systems and drainage systems and include additional support. And there are many companies that currently offer upgrades to your house with green roofing systems.
http://www.liveroof.com/
http://agreenroof.com/
My roof doesn't have much of a slope but very sloped roofs would have the soil erode. I like the idea but very few houses are designed to withstand having sod on them. My neighbors probably wouldn't like as much.
And extremely heavy especially when wet. Chances are your roof would collapse if you covered it with turf.
They say it's better to paint all roofs white.
Fantastic insulation, prevents reflected heat and it's great for insect and bird life and it's relatively cheap to install...
http://www.google.co.uk/search?q=turf+roof&client=safari&hl=en-gb&source=lnms&tbm=isch&sa=X&ei=6GDlUbLkJ8WU0AW304H4DQ&ved=0CAkQ_AUoAA&biw=1024&bih=672
