I want to put a green roof on my house, but all the plans I find include pond liner, mesh, etc, to make it work. Many sites also refer to green roofs being around for centuries in Scandinavia, and I’m sure other places had them too, so how did they do it? I’m working largely with timber, and not wanting to utilize anything I couldn’t make by myself or with a small community, and using only hand tools. I’ve just wasted 40 min. searching for this crap on yuppie “green” sites, anybody have any insight?
Trollsplinter-
The only home made thing I can think of to put under a sod roof would be some wide (as wide as you can make 'em) and long (as long as you can make 'em) hand split cedar planks.
The cedar should last a while because it’s fairly rot resistant. But even so, they make good roofs because of the slant and the drainage. Sod sitting on it might mess with the drainage and create water backing up and leaking in.
You do live in the land of big cedar so finding some good logs to split nice big planks from should be possible. But you also live in the land of more rain than anywhere in the lower 48, so making a good waterproof roof is important.
I know this isn’t home made but it is making use of something that gets tossed. I have a friend who gets huge ( I mean huge) pieces of super heavy duty plastic from commercial greenhouses. They need to replace it and they usually do it well before it starts to leak. He gets it free for hauling it away. So if there are any greenhouse operations around check with them. With sod on top of it it won’t be exposed to light degradation and it won’t be subjected to a lot of freezing either so it might last a long time.
Ai hear you can grow stuff in cob. Try wikipedia (sry, link not working).
The only advice I can give you is layers. Cedar planks is good, but how about natural wool? It’s insulative and has a reputation for not leaking. I’ve never tried it, but I would think that cedar, wool and maybe some kind of strawclay barrier and then sod would work very well.
I took a good look around the web, too (tour provided courtesy of Google), and couldn’t find any DIY green roof instructions that didn’t involve synthetic materials.
If anyone here has access to an academic database (I remember Jstor, ProQuest, Art Index, and WorldCat from my days as a student in architectural history), perhaps they may lead to some architectural studies of traditional green roofs in Scandinavia. Graduate papers on architecture can be very detailed. I know from personal experience, I had to write them. 
Most scholarly articles are only accessible through paid databases (or in a University library’s journal collection), but those articles often cite published books that are informational treasure troves, and those books might be available at the public library or through interlibrary loan.
I’m pretty sure a membership to the seattle library will get you access to a lot of those databases as well.
The traditional matterial we use in norway when it comes to waterprofing these kind of houses were layers of birk bark(funny word combo) coverd with tar…
Well, I’m beginning to develop a plan. There is a ton of old growth cedar lying around out here, and I think there is some potential in the wool idea, felted tight as all hell. Trail and error looks like a good option for me right now. Perhaps just keeping it simple and not putting a ton of dirt on my roof is the best answer. Thanks for all yr ideas folks!
I think I’d do it by putting the roof at a decently steep angle so that water doesn’t pool there (maybe 3" or 4" in 12" pitch.) I think I’d also put a layer of river rock between the dirt and the cedar - plain water isn’t going to make the cedar rot very fast but all the little microorganisms in the dirt might.
I stumbled upon an answer in a book i checked out from the library on log cabins. All it said was birch bark was laid between two courses of planks.
Since this way of covering a roof is immensly cool and superbly beautiful I wish to resurrect the thread:-)
First off, this is what we’re talking about, thats my cousins place btw!
And another one:
So, first you lay a roof, cover it with birch bark, then cover that with tar and/or clay. On top of that you put peat from the nearest bog and sprinkle a thin layer off soil on top for good measure. Sow your seeds and watch as your cabin becomes one with nature. Oh, and by the way, the traditional way to trim the grass is by letting a goat feed up there every once in a while.
Those are awesome pictures.I like the idea of green roof no plastic.I was thinking on building a carport with green roof,now that I know I dont need plastic I am more likely to do that.Thanks for the info
very cool. the birch bark makes perfest sense, as it takes a long time to rot. it is common to find a fallen birch tree where the actual wood has rotted away, but the bark still forms a tube. the bark can last years longer than the wood.
Awesome. Clay I can do, tar, not so easy. Thanks for the post!
No worries mate!
I really, REALLY like green roofs, seems like such a logical way to make a roof for some reason:p
Tar:
I also read somewhere that fire-killed pine was best for this, but apparently any resinous pieces can be used.
I once considered building a grass roof to absorb the solar insolation on a Southern exposure (in Alabama). I considered sprinklers too. But, after pondering the weight of wet soil and grass (for an existing structure), I decided that the better idea is IVY. If you want green shade, you don’t have to put soil ON the roof. Let vines grow over it.
That is, unless you’re more motivated by novelty than practicality.