Posted by: Meghan Hendricks
Did you know that the concept of a green roof isn’t really a new concept as the recent trend in green roof construction would have you believe?
Green roof construction actually dates all the way back before Biblical times!
I get pretty geeked about history, so when I had it pointed out to me at our Green Roofs Workshop last Wednesday that green roofs actually date way back, I decided to do some of my own research…
The Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World, and one of the first extensive green roofs, were most likely built during the reign of King Nebuchadnezzar in what now is Iraq. More than 10 miles long, according to archeologists, this spectacular green roof was a structural marvel as much as an artistic one.
There are two ancient historians whose accounts of the gardens’ construction sound very similar to the modern day green roof concept. Greek historian Strabo during the 1st century BC said that “it consisted of vaulted terraces raised one above another and resting upon cube-shaped pillars. These are hollow and filled with earth to allow trees of the largest size to be planted. The pillars, the vaults, and terraces are constructed of baked brick and asphalt.”
In addition, the Greek historian Diodorus made his own account of the gardens also in the 1st century BC. “The Garden was 100 ft. long by 100 ft. wide and built up in tiers so that it resembled a theater. Vaults had been constructed under the ascending terraces which carried the entire weight of the planted garden; the uppermost vault, which was seventy-five feet high, was the highest part of the garden, which, at this point was on the same level as the city walls. The roofs of the vaults which supported the garden were constructed of stone beams some sixteen feet long, and over these were laid first a layer of reeds set in thick tar, then two courses of backed brick bonded by cement, and finally a covering of lead to prevent the moisture in the soil penetrating the roof. On top of this roof enough topsoil was heaped to allow the biggest trees to take root. The earth was leveled off and thickly planted with every kind of tree. And since the galleries projected one beyond the other, where they were sunlit, they contained conduits for the water which was raised by pumps in great abundance from the river, though no one outside could see it being done.”
The construction of the Hanging Gardens was pretty advanced for its time. The accounts of the irrigation system are impressive considering now-a-days in the modern world people still struggle to conceptualize an irrigation system on their own roofs. And, like the Taj Mahal, this ancient wonder was constructed because of a couple of love birds—King Nebuchadnezzar had the gardens constructed to lift the spirits of his sick wife.
Not as fascinated with the aesthetics of green roofs as you are with their functionality?
Well, the Scandinavians have been using green roofs for practical reasons for hundreds of years. Limited resources and a rugged environment forced Scandinavians long ago to get creative with insulation. Early methods simply used heavy timber, covered with birch bark for waterproofing, and topped with rolled out sod for insulation.2
Hope you enjoyed this little History of Green Roofs 101. When you are constructing your own green roof, take a minute to reflect on the fact that you are participating in something much bigger than just installing some greenery on your roof—you’re participating in a piece of history!
1 “Hanging Gardens of Babylon” Wikipedia http://en.wikipedia.org/wiki/Hanging_gardens_of_babylon
2 http://www.ehow.com/facts_5189069_history-green-roofs.html