Sharing experiences and thoughts of the eco-build on 97 Kings Dr. has always been the number one aim of this blahg, and honesty and openness of this experience is vital to the progression and whittling down of the alternative-build process to become a more simple, and truly ecological undertaking. One aspect of the home that we may wish a time machine rental-shop existed for, would be the 'green' roof. Due to it's near 225 kg/square meter (500 lbs/ square yard) loading of soil and plant matter, the extra engineering required in the design of the sod roof on our project has made the cost ticker jump quite a bit, and the added engineering was just the beginning to the investment increase. Necessitating nearly 4 times the amount of joists to support the turf roof area, as well as local regulations calling for an extensive waterproofing system, the material expense has also been a bit frightful.
The waterproofing process has been a bit of an interesting procedure that seems to be at slight odds with the whole ecological ethos of 'green' builds. Below is a cross-section of the living roof system:
And a brief sequence of application of the waterproofing system by New Zealand's Nuralite company.
Somewhat needless to say, this method of water-proofing is nearly second to none in effectiveness and quite bulletproof. But nearly equally needless to state, is how chemically and carbon intensive it is. There is not much natural about it, and the processing and creation of such products makes a 'greenie' wince. This is not meant to vilify or condemn Nuralite, but looking back on the very large and time-tested history of living roofs, it isn't hard to see the environmental disparities and stray from the truly natural & original technique the Scandinavians and Icelandic began back in the middle ages.
So, to get a clear and more balanced picture we have performed a bit of research into said roofing history. Due mostly to lack of resources, the ingenious people of Scandinavia & Iceland developed the method of insulating and 'shingling' their roofs with sod. With the absence of Nuralite and bitumen dealer, the people of these countries turned to the bark of Birch trees as their waterproofing membrane like many other observant native peoples of the world have, check out the birch bark canoe below!!
After placing a layer or two of birch bark down they would then lay a sections of sod with the grass face-down to help prevent the soil (preferably quite sandy for good drainage and minimal humus/organic material) from decomposing the bark to quickly. Another layer right side up and it's nearly there. To hold it all in place the use of 'turf-logs'. In the rough schematic below you can see the birch bark 'leaves' beneath the two layers of sod being held by the 'turf-logs'.
This post seems to be getting a bit long winded so if you feel so inclined please check out this link here to get the rest of the story, or ask away in the comments section. Thanks for reading and look for some Weekend Supplements coming up soon!
UPDATE: Look at this 'all-in-one' sod-roof tiling system pioneered by Toyota of Japan- wild!
Here is a link to a site that talks about it briefly: click hur