How To Create A Rooftop Garden

Jul 4, 2015 |

With innovation and modernisation, a lot of land has been developed leaving very little outdoor space for gardening. The roof top thereby provides an unused and ideal space to benefit from all the gardening virtues. In most urban areas, roof top gardening has provided an ample outdoor living space.

Being a very simple do-it-yourself process, it is worth embracing because of the following;

  • Heat Reduction and insulation; the soil from which plants growact as an important insulation material during hot weather or when it is snowing. Consequently, the fact that plants are lighter in color, reflect more sunlight thus maintaining a cooler roof. In fact according to statistics, green roofs can reduce heat by up to 50 degrees.
  • Air Purification; considering the photosynthesis process, plants take in carbon dioxide emitted by people and even cars and turn it to fresh air (oxygen) for breathing
  • Storm Water Management; in as much as it does not stop all storm water, green roofs reduce its volume by absorption. Pollutants are also picked before drainage. In the long run, more community money is saved as a result of lesser installation of storm water management systems
  • Additional Green Space; additional green space provides biodiversity in urban,   developed areas with limited areas for wild life.By providing habitats for birds, insects and pollinators, they are said to serve as “stepping stone habitats” connecting isolated habitats.
  • Reduced Energy Costs and Emissions; roof top plants provide shade thus reducing the amount of energy required to cool the building. Plant media absorb heat during the day holding the heat into the night therefore protecting the building from being extremely cold throughout the night. Reduced energy consequently reduces greenhouse gas emissions and utility bills

Measures to be taken

Before building a roof top garden, simple measures need to be taken. The very first measure is to ensure the possibility of creating a garden on your roof. This is through;

  • Checking local ordinances, set measures rental property rules and home owner association regulations to find out whether roof top gardens require special treatment or are allowed before wasting much time and money on something prohibited.
  • Ensuring the roof will be able to hold the rooftop garden weight. This is because most houses with flat roofs are not strong enough.  By consulting a structural engineer, you will be able to establish how much weight your roof will be able to hold. They will also advice on your house safety since some buildings are simply not designed for additional roof top weights and others support only limited weights.
  • Considering the use of very light containers, flooring furniture and lightweight potting soil important for roof protecting against damages

Secondly, work out on the best way to access the roof top. It is usually advised to seek services of an architect or a roof top garden specialist for advice.

Again, by employing the services of a designer, find out the best layout for your garden. The designer will also help on the best flooring to employ, stones to use and the decking. Materialse.g. fibreglass or form planting containers and plastics are encouraged to pavers

At this time the planting scheme should have already been worked out. This is through plant selection best suited for natural light, area humidity and wind. If with any doubts, consult with a planting expert or even a landscape designer.

Now get the containers and furniture with the size dependent on the type of plants and integrate them well with the planting scheme. Remember they should be stable and lightweight

By installing an automatic irrigation system, garden watering worries during hot weather should be a thing of the past. Alternatively consider a water storage system or if it’s easier to access your rooftop garden, the cheap and simpler method of carrying water up the roof in buckets can also be employed though not very effective.

Consequently, since it is usually very windy on the roof top, it is a good idea to consider windbreaks that will disrupt the flow of wind rather than those that will try to stop it completely e.g. trellises and latticed windbreaks. Solid windbreaks that do not allow some wind flow are not encouraged since they will be knocked down easily by very high winds. Also, wind flow should not be eliminated but reduced.

Setting up a Roof Top Garden

With only three cultivars of sedum for the creation of rich tapestry (red and gold), and an approximate roof top space of 5 by 8 feet and free draining light soil, your rooftop garden will be of thick succulent foliage within a short time span

Materials Needed

  • Marine-quality plywood
  • Plastic liner, hammer, nails and drill
  • General Compost,Insulation Material and Perlite
  • Sedum Roof Mats (optional)
  • Three cultivars of sedum (10 Coral reef, 10 Angelina, 10 Spirit); preferred because of their drought resistant nature and the thick roof surface cover they exhibit.
  • Styrofoam peanuts; for drainage

Planting and Aftercare

Measuring with the size of the roof cut a piece of marine quality plywood and cover with a plastic liner. Nail it firmly to the roof and create approximately two inches deep wooden planting frame on top through fastening of wood planks to roof edges thus creating a sturdy framework.

With Perlite, Insulation and General Compost mix fill the frame. Ensure good drainage by drilling holes into the bottom edge of the wooden frame and remember to push insulation into these holes so as to prevent filter material from draining too. Styrofoam peanuts is another good alternative for creating drainages

Into the growing medium, plant the sedums. Since they (sedums) don’t like wet roots, clear the roots that might have fallen on the plants during winter and ensure that the drainage holes are open. Alternatively, consider purchase of sedum roof mats that can easily be rolled out and attached. Always confirm with designers and engineers to be sure your roof support the sedum weight.

Despite the fact that a rooftop garden is costly to maintain due to repairs and damages that might be caused by other ecosystem habitats e.g. rodents, small reptiles, insects and bugs, it is a lovely solace place when the above guidelines are considered and proper advice from specialist embraced to the latter.

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