My rooftop balcony became a green roof!
I live in an apartment that has a rooftop balcony. When I first saw it, my initial thought was: “what a great place for parties!”. But today that rooftop is much more than a place for parties. I built a green roof! Today it is a urban garden, a composting station and a healthy food source!
The first steps
It all started with a few vases and pots. I never had any contact with agriculture before so a lot of stuff was new to me, and I learned a lot from it. In a few months I was eating vegetables and fruits grown in my own garden!
Short after I also got into vegetable composting. When I heard about it I though it would be messy and hard, but it is quite easy. Think of it as recycling for vegetable leftovers. Some countries already have this as a part of their urban waste management systems, but in Portugal that is still far away…
So I started separating my vegetables out of my domestic waste, just like I did for plastic, paper and glass. The special thing about this was that the recycling facility was at my balcony.
The setup was a bit tricky: The vegetable waste first went to the light gray boxes on the right (1). Fruit flies and “other workers” would come to start to decompose everything. To let everything dry, these boxes had small holes in the bottom, to let all the liquid drain out of it into box (2). This liquid is great fertilizer that you can dissolve with water to put in your plants — and yes, it smells funny. After a few weeks the content was moved to box (3) and later to (4), where it was ready to be used a growing medium for plants!
If you have a garden, composting is a must!
This system works best in the summer. In the winter, since its colder the vegetables take much more time to decompose, just like in your refrigerator. Rain is also no good, as water would be trapped in box (2) and mess with all the process…
Thinking on the next step
One interesting thing that I learned about plants, is that their size is proportional to the amount of soil they have. If you put a plant in a small pot, it will always be small, but if you put it in a larger pot it will grow much bigger. So next time you see a big tree on a small pot, it is “on steroids”.
What I needed was larger pots so my plants could grow. I actually bought 3 of these, results were pretty good, but the pots are a bit expensive…
At that time I also started reading about green roofs:
A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane.
One thing I learned is that green roofs have to be carefully designed by professionals, so they can retain and drain water correctly, and so that their weight doesn’t cause problems to the building structure. I liked the idea a lot, and after all I have space in my rooftop. Agreen roof would be even better than having a lot of large pots, as the area for plans to grow would be larger!
Building my green roof
I don’t like taking unnecessary risks, so I come up with a solution that I like to call as a green roof in a box.
In my solution wood pallets are connected together and sit on the floor. These pallets work as the base of a big box, whose walls are made of wood deck. Inside the box I can safely create the green roof.
Like this I won’t risk the building for bad water draining, because below the box water still flows normally, and if I add too much weight to it, the wood pallets will break before than the concrete below (at least I hope so!).
Plus, there is also the fun part of it: building it!
In an industry near by I saw a bunch of used and damaged pallets, I am not afraid of asking for stuff, so I asked one of the guys working there if I could take a bunch, and he gave me 3 for free!!
I started working in the base of my green roof and after joining the 3 pallets in a row, I come up with what my wife called… “a train”:
For the space in my balcony this shape was not good, so I changed it a bit, and went for an ‘L’ shape, with two pallets in a row, and another pallet on the right.
Below the pallets I used rubber deck floor to avoid direct contact of the wood to the wet floor after raining.
Now that I had the base of the box ready, I had to build the walls. I want something resistant to the outside weather. I found some 50x50 cm treated wood deck panels in a shop for a nice price.
I bought a few (actually a lot) and joined them together to form the walls. I used screws to put everything in place.
This was the part where I spent more money, as I had to buy all the panels.
Now all I had to do was to place the panels on the edges of the box to form the walls. I used steel triangle brackets to do it, I had to find the right spots to put the brackets, so that the walls are strong and can hold all the soil and awesomeness inside. After placing the walls I added a few more brackets in the corners of the box, to make everything as stable as possible.
To hold water in the bottom of the box, I created a few bumps over the pallets and placed waterproof rubber over it. This allows the creation of small buckets that retain water in the bottom. If there is excess water it drains to the sides.
Finally I had to cover the walls. As you can see in the pictures the walls have spaces between, and I need to keep the soil on the inside of the box, and not to spill outside. So I wrapped the interior of the box with weed blocking cloth. This ensures that soil is kept inside the box, and water drains out. Exactly what I need!
So at this moment I ended up with a nice box, with an area of approximately 2.75 m², 29 square feet. “Nice job” I said to myself!
A lot of screwing had to be done to accomplish this, so special thanks to Gonçalo Borrêga that borrowed me a pair of electric screwdrivers!
Building the soil
Now I had to add soil to my box. The soil had to resemble real soil, so I looked up on how real world soil is composed.
Back to my tiny world soil, at the bottom I placed a layer of expanded clay rocks, then some bare soil (with sand and rocks). This resembles layers B and C of the image above. On top of this layer I place the compost: the organic matter of layers O and A.
The bottom layer guarantees that humidity is kept while the top gives all the nutrients to plants. Rocks and sand are great for plant roots to properly ground the whole plant. As for the compost on the top layer, I had plenty in existing pots, most of it homemade, but still I had to buy some… yes, shame on me for buying organic material.
The result
This is my green roof a few months after I build it:
Now that I had a wider soil I moved the composting station to the inside of the box an placed it directly in the soil.
With this I got no more problems during rainy days. The water drains directly to the soil, giving all the nutrients to it!
I also mix a few soil to the vegetable leftovers to speed up the process, and it is running great even during the winter.
What do I get from my green roof?
I get many things, but the best is food! Every week I pick something!
Eating the vegetables that you planted and cared for is an incredible feeling. This article clear describes it:
Watching a seed blossom under your care to become food on your and your family’s plates is gratifying. Growing your own food is one of the most purposeful and important things a human can do — it’s work that directly helps you thrive, nourish your family, and maintain your health. Caring for your plants and waiting as they blossom and “fruit” before your eyes is an amazing sense of accomplishment!
Since I don’t use any pesticides, sometimes I need to rush to eat my vegetables before others do! :)
The other thing I get is pleasure and well-being. I am contributing to the planet, through less waste due to composting, more vegetable diversity, and I am providing a place for bugs to live on, for birds to feed on. I am also breaking capitalism, since I get food without paying for it!
The great news is that spring is coming!
I wonder how many tomatoes can I get from my green roof?
