Do It Yourself Green Roof
Lately we’ve been talking about the pros and cons of building our own green roof. The discussion has led us to looking at whether or not we can do it entirely on our own – as in using readily available building products instead of using a proprietary system.
Proprietary Vs. Custom.
There are benefits on both side. Obviously, if money were not an issue, I would always go with proprietary systems: although you may pay more consider the benefits: warranty, years of research, materials that “fit” together, specifications and instructions governing installation, maintenance, etc… In a word – piece of mind.
But all of this comes at a price and if the purpose of our society is to encourage and promote green technologies to anyone, anywhere, then we better know how to put together our own custom system. After some discussion we decided to go for it. We’re going to start as basic as we can. With a few shopping trips to local building supply stores. The next step will be to test the materials in a series of mock-ups to determine if our purchases are feasible. And from there, we search for a guinea pig – er, project to try it out on.
STEP ONE: Go Shopping.
So Charlie, Heidi, Jonathan and I have been doing some shopping. We’ve been roaming around Home Depot, Re-source and various landscape supply stores trying to put together a list of components that could work.
Once we find all of the pieces, we’re going to build a few mock-ups of a Mini Green Roof and a Mini Green Wall, that is to say, we won’t be throwing our custom recipe on to some ones membrane until we’re sure it works. Here is a list of the products we’ve been specifying. Feel free to leave some comments and let us know what you think. If you’re doing your own investigations into this field, we’d love to hear from you.
1. Root Barrier
Just a simple roll of plastic, which you can find at any Home Depot – pennies a foot. A 102″ X 59′ roll is just $28.70 CDN. at Beaver Lumber.
2. Protection Board
A 1/2″ X 24″X 96″ piece of polystyrene rigid insulation sells for about $6.99 CDN.
3. Plastic container
This won’t do the trick for a typical green roof, but we’re wondering if it will work for our little roof pods. These are simply planting trays. Cost: Free.
3. Drainage Layer or Moisture Retention Mat?
This one has been harder to come by, but so far we have a rough quote of $4-500 CDN for a 4′x50 roll for a drainage mat from Nilex.
3. Drainage Mat
We found this pond underlay at Landscape Supply (http://www.landscapesupply.ca/products/product.php?pid=1554). It is a 10oz. per sqf non-woven, polypropylene needle-punched underlay that protects. It comes in 15′ wide rolls. We’re wondering if something like this could work as a drainage layer.
4. Filter Fabric
Filter Fabric/Weed Block is just $15CDN for a 3′X 50′ sheet.
5. Moisture Retention Mat (Fleece)
This is an optional item, but it would really improve performance and reduce maintenane by acting as a resevoir for the root system. We’re looking for some kind of moisture retention mat or fleece. We’re open to suggestions here. Anyone have any good ideas? How about carpet underlay?
Growing Medium
For the mini roof we may just use a garden soil with high concentrations of peat. For a real green roof, we will substitute Perlite. We found this 30L bag for $2.99CDN.
As we find more products, we’ll up date the blog. You can also search our blog archive for more info on how to install your own Mini Green Roof and Green Wall.
More soon.
Great start! I’m on the same trek shopping local stores as much as possible for materials. Water proofing and root barrier…pond/pool liner (45mil HDPE from Lilypons, ~$.80/sf, not local but the cheapest I’ve found for that thickness). Drainage on flat roof…pebbles. Water retention on sloped roof…old carpet/rug or carpet pad is a great idea! Did it work? Landscape filter fabric seems like the obvious choice but I’m worried about it causing slippage on sloped roofs. Growing medium…80/20 expanded slate/compost, a little heavier than perlite to avoid it blowing away. Someone local even used 50/50 packing peanuts/perlite and says it worked great but it had to be weighted down with mulch due to wind. Keep us updated!
Thanks for the comment Frank. We’re working on our soil spec a bit. I will let you know how that works. We haven’t tried the underlay yet, because no one seems to want to take on the risk. We’ve been using a water retention mat donated by Xeroflor instead. What we need is someone to donate a shed or something so why can try this out.
If you have any pics/projects/sourced-products you’d like to share, feel free to tell us more.
Regards,
Bryce
It sounds like you’re well on your way. All the best when you actually put the project together. I like that you got that xeroflor donated. The carpet underlay may work, but I’d be concerned that it may leech some chemicals/toxins into the plants potentially. When they make the underlay, they’re not superconcerned with what chemicals or products they use to make it as they’re not thinking that it’s going to touch plants. Since Xeroflor’s made for plants, I’m thinking that’ll be your best bet.
Thanks Gavin.
The issue of toxins was raised after we installed it. We’re looking into ways to source some kind of “organic” underlay material. In the meantime, we will be using Xeroflor’s water retention fleece. But the long term goal is to develop a green roof system that can be sourced by anyone, so we’re still looking for the right product.
Bryce