People look at me funny when I insist that I and the land want a roof top garden. The land is below the road, so most people will only ever see it from above. I want to blend the roof into the land and improve their view which is already drop dead gorgeous. That is one of the reasons I want to see a living, breathing garden as opposed to the carcass of a dead corrugated iron roof, which is my cheap option. Building a roof garden is an added expense and will require extra care and effort initially, but the benefits for my container, me and the land will make it worthwhile There are other reasons that make more sense than aesthetics alone. Energy Efficiency: Whilst mountain biking in Scotland some years back, I hooked up with a group of young people on the Island of Hoy in Orkney Islands who were restoring a 'bothy' or mountain refuge hut. We rebuilt the damaged stone packed walls, replaced the trusses and the roof surface. The roof surface had many layers including battens, plastic sheeting, natural slate and the top layer was sod or big squares of grass. This was for insulation and protection of the water protection materials we used below (plastic sheeting and slate). Roof gardens have been used for centuries for practical reasons and I am going back to those roots. Roof gardens absorb energy by being on top of a structure. They provide natural noise and thermal heat insulation, thereby cutting down on electricity bills. One of the factors I have to consider with a container home is the heat. Everyone who has ever worked in a container site office tells me - forget it, its hot, you are going to cook. But then I look at their unprotected roof and walls, the lack of ventilation (a single door and a closed window) and I can understand why - there is zero insulation and cross ventilation. Then there is the other benefit that roof gardens absorb rainfall and sun, meaning less water runoff, less flooding and less erosion. When I was visiting Seychelles they had massive water shortages and were running on badly maintained desalinisation systems. Every afternoon I witnessed torrential rains with rivers so deep running down the steep sealed roads and into the sea, that they moved cars. I just could not understand how this could be allowed to happen. I know such downpours are not all year round, but in rainy season Seychelles has so much rain and still they were experiencing a water crisis. Instead of making a serious effort to catch their water in a 'green' manner - improving their municipal catchment areas and using their own roofs, they were relying on donated First World desalinisation plants that required maintenance that they don't care to do properly - and it costs someone a lot of money to fund their slack ways. I know this because I shared accommodation with one of the contractors sent to try and train the Seychelois to maintain the plants but the Seychelois were more interested in going fishing and seldom bothered to pitch for work. In bigger cities roof gardens decrease the excess heat caused by urban heat islands. What is an Urban Heat Island? It is a city where we seal off the earth with tar, concrete and glass. This 'modern civilisation' changes the environment and the weather we experience in that area. Japan has massive heat build ups from their cities and it is now a requirement to develop roof gardens. Ever been in Cape Town city on a hot windless day? Roof gardens would actually help to cool the city down. I personally detest walking and driving in cities and avoide them if I can help it. Everything is so hard and uncompromising. The earth is sealed off and everywhere there are dead surfaces and dead air inside of the shells we work and live in . The need to change and control our environment has gone too far. We are now damaging our health and the health of the earth. Provides for Nature: The thought of a roof top garden is peaceful and calming. It provides for the birds and the insects which is much nicer to me than sealing everything with concrete and steel. My roof garden will give back to nature some of the area the house is occupying for plants to re-oxygenating the air. Angle of roof, strength and material: The roof will have a gentle 5 degree slope and be mono pitched with a wire mesh batten on the end before the gutters to allow for drainage, but not the loss of rocks and plants. I will be planting an extensive garden which has a thin soil / sand base with the drought resistant plants we have in the Cape such as the creeper plants already growing on site. It will still have to have a number of trusses to support the weight - expected to be less than 50kg per m2 when water saturated, but this won't be a problem as the shipping containers are built to be stacked, fully loaded. The frames are very strong. I have not decided what the sheeting must be - steel, wood, something else? Engineering specs to follow. Vegetation: My roof top garden will be of the low-weight extensive variety. It is important that the plants be able to take care of themselves for the most part and need to be drought resistant. Where I rent presently there are flowers that need a lot of water to keep them alive. On my own land in comparison, there are already plants growing in the rock walls and flourishing - without any help from me. The roof must take care of its needs naturally - it must be self sustaining. The sandy soil natural to my plot will be a thin base, probably about 5cm, mixed with rocks. Water tightness: The container roof itself will be rust protected and then coated with the new polymer product from Armour Colour . I will then build a second roof over it to be 'doubly' sure that there will be no leaks and deterioration to the container roof itself. This second roof will overhang to give more outdoor space along the length of the front of the container and to protect the roof and walls from sun and rain.
It is this second roof that will hold the roof garden. I will protect it again with the Armour Colour product which I am told is root and water resistant and then grow the garden on top. It is a flexible product similar to plastic in some ways which means no chance of minor cracking. Armour Colour is a bi-product used in the building of roads and it is now used as a paint AND in the building of swimming pools. When applied thickly into a shaped sand 'mold' it is structurally strong enough to take on the pool shape without re-inforcement. And it is obviously waterproof. An alternative sealer is bitumen but this is messy and to do a good job, I will have to call in experts. ABE has some options and a quote to seal the container roof directly - 12m x 2.5m was R2 500. The ABE product they use is root resistant and the garden on top will actually protect the sealer from sun damage. But I am leaning towards the Armour colour product because it is cheaper and anyone can apply it and I don't need special tools - just a paintbrush and some care and attention to detail. Drainage: The sand itself is good drainage material so won't hold onto too much excess water. I am not sure if I will need to put another layer of drainage material to stop the sand and stones moving towards the gutters, but with only a 5 degree angle, I don't think this will be necessary for the whole roof. Stone chips and geocloth at the steel grating near the gutters should do the trick.
If I do need to put something on to stop wind and soil erosion in the early stages, a length of old pilchard netting from the fishing boats will help keep the sand on the roof whilst the plants establish themselves. In Cape Town we often use pilchard nets on our take off sites. The nets slowly rot away / biodegrade over time with exposure to the sun and the plants grow up through them. Water will drain to a grey water tank for future use.
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Building an Eco Home 