Instructions for making my green roof in 6 steps. When done correctly, green roofs have many benefits, including water conservation, reduced risk of flooding, aesthetic impact, improved air quality and habitat creation. While large projects should be left to specialists or green roof companies, small projects are relatively easy to implement as long as certain rules are followed. With these instructions you can build your own green roof.
Before you begin, you should ask yourself two things:
At what angle can I install a green roof?
• It is not recommended to build a green roof with a slope greater than 10° without the help of an expert.
• It is recommended to build a green roof with a slope of at least 2°.
Can the existing structure withstand the weight of a green roof?
• Simple green roofs weigh between 60 and 150 kilograms per square meter.
• If you are unsure whether your roof can support this weight, contact a professional.
• When calculating the weight of the green roof, you also need to consider the weight when it is saturated with water or snow.
• If the existing roof cannot support the additional weight, you can reinforce it with wooden supports.
Step 1 – Green Roof Layers
The layers of a traditional green roof are shown in the image below:
Homemade green roofs require a simpler option with only 3 layers:
1. Waterproof membrane
2. The substrate
3. Vegetation
Step 2 – Waterproof membrane
Most roofs generally have an impermeable or waterproof membrane. Green roofs require an additional layer of waterproof material that is also resistant to plant roots. Ideally, this should be done on a single sheet that covers the entire surface.
Robust 1 millimeter thick pond covers, which you can find in garden shops, are ideal. They are attached to the ceiling using conventional sealant. TIP: Mark drains and exits so you can open them before installing the next layers of your green roof.
Step 3 – Drain
Excess water should be able to drain away from the roof. Drain holes must be opened from the frame of the green roof to allow water to drain into the gutters.
Drainage is very important; The roof must not be wet so that the drainage openings are clear. Use layers of pebbles to prevent clogging. Pebbles can also be placed around the edges of the green roof to prevent vegetation from spreading.
Step 4 – Substrate
The depth of the substrate determines the vegetation that will grow in it. Most self-built green roofs are 7 to 20 centimeters deep.
The substrate must be light and low in nutrients. Avoid using regular garden soil as it is very heavy when wet and has a very high organic matter content that promotes unwanted growth and vegetation.
If you choose to make your own substrate, a good combination is to use 70.80% inorganic material such as Tezontle or ground bricks and 20-30% organic material such as compost.
Step 5 – Sowing
The most exciting part of making a homemade green roof is the planting. You can design your green roof to attract specific plant and animal species or to reflect local biodiversity. Many suppliers of gardening and landscaping products now offer seed mixtures for green roofs that are specifically tailored to the weather and altitude.
Green can be applied in different ways:
1. Pre-seeded mats, these are delivered directly and laid in a similar way to turf and are usually made of sedum or wildflowers.
2. Direct sowing of shoots, seeds or small plants.
Plant types:
Sedum or succulent plants. These are alpine plants that are used to living at elevated altitudes. They require very little care and survive all year round. Its flowers attract a variety of insects in the summer months.
Wildflowers: They can survive in a nutrient-poor substrate and offer many options. The meadow flowers that are most suitable for green roofs are those associated with limestone and limestone environments, such as: B. Helianthemum, rose, campanula, parchment and thyme.
To learn more about which plants to choose for your green roof, read the following article: Choose what you want to plant on your green roof
Planting tips
• Avoid monocultures, because the success of a green roof depends on building a community of self-sustaining plants.
• The steeper the roof is, the more important it is to ensure that the plants above tolerate the drought best, as they receive the least amount of water.
• To reduce the need for irrigation as plants become established, a green roof should be planted in spring or fall.
Step 6 – Maintenance
The maintenance required for a homemade green roof is generally minimal. To ensure that your green roof survives, you should only check the following points once or twice a year.
o During the dry season, especially in the first year, make sure that the plants have enough water so that they can spread properly.
o After the first year, only water the plants if the drought lasts longer than 6 weeks.
o Make sure drain openings are clear of debris or plants.
o If there are areas on the green roof that have not grown, you can replant them with seeds or shoots from existing plants.
Considerations for green roof design
A frame made of sturdy material should be built around the green roof. This means the green roof material is preserved. Make sure the frame does not block the roof drain. When building this frame and opening the drain holes, be careful not to damage the waterproof layer. If there is a possibility that the plants will get into the building and endanger the structure, a gravel border of 30 centimeters should be installed.
If the slope is more than 20°, you must ensure that the green roof does not slip. To avoid this, you can install grid-like barriers over the waterproof membrane.
You can also divide your green roof into boxes or demarcated areas so you can walk between spaces and coexist with nature.
To inspire you, learn about 30 incredible green roof designs
Environmental aspects of green roofs
To maximize the environmental benefits of your green roof, you must consider the following points:
• Avoid using chemicals and fertilizers on the green roof as these can contaminate the water filtered there.
• Try to purchase all materials for your green roof from local suppliers to reduce the environmental impact of transportation.
• Consider using recycled materials from contractors and vendors. You can also use gravel as a base, but make sure it is clean.
By Val Escobedo. A green blog