Principales errores en cubiertas ajardinadas
Green roofs offer great aesthetic and environmental benefits, but as with any construction project, there are common mistakes that can compromise their success.
Below, we will explore the main mistakes that are made when installing green roofs and how to avoid them.
1. Root-proofing: the crucial first step
One of the most common mistakes when installing a green roof isnot choosing the right waterproofing, especially one that is anti-root.
As Jordi explains in the video when making a green roof, you should always choose an anti-root waterproofing.
If this type of waterproofing is not used, plant roots can perforate the layer, causing structural damage that can be costly to repair.
In addition, it is important that the waterproofing sheet is well bonded to the slab, as this helps to locate and avoid future problems.
We use GreenMastic waterproofing, which is hot-applied directly onto the slab to ensure that it is completely waterproofed and anti-root.
This type of material ensures that water does not move under the sheet, preventing leaks.
2. Selecting the right substrate for green roofs
The second mistake, and probably one of the most common, is to think that any type of substrate or soil will work for a green roof.
Each type of plant you want to use will require a specific substrate.
It is not enough to use just any type of soil, as the substrate must meet water retention and drainage requirements.
- If the substrate is too clayey, there is a risk of waterlogging, which can lead to the plants dying.
- If the substrate becomes waterlogged, the plants will die.
- If it drains too much, the plants will also die.
Therefore, it is essential to select a substrate that balances these factors to ensure the success of the cover.
3. Choosing the right plants for the use of the canopy
Another significant mistake is not considering the intended use of the groundcover.
It is essential to know how the deck will be used before selecting plants.
A deck where we are going to lie down, and need grass, has nothing to do with a deck where we just want to look at it.
The plants selected should match the expectations of the user, whether it is to create a low maintenance green area with sedum or a more elaborate garden with shrubs and aromatic plants.
It is not uncommon for customers to ask for native plants such as lavender and rosemary, expecting low maintenance, not knowing that these plants require a deeper substrate and regular care.
4. The importance of an irrigation system on green roofs
The fourth mistake is to assume that green roofs do not need watering.
In our experience, many green roofs in Spain do not have an irrigation system installed, which can be disastrous in periods of prolonged drought.
Irrigating a green roof is not more expensive, in fact, it can actually make the installation cheaper by reducing the thickness of the substrate.
An irrigation system ensures that plants receive the necessary water all year round, especially in dry climates.
Even in areas where you might not think it is necessary, such as Madrid, lack of irrigation in drought years can cause the cover to fail completely.
5. Regular maintenance for a healthy ground cover
Finally, there is the belief that green roofs do not need any maintenance.
While some solutions, such as sédum roofs, require very little care, all roofs need some attention to prevent them from becoming a barren or weed-filled wasteland. Jordi points out that ‘even the sedum roofs, which do not need pruning or nutrients, require annual weeding’.
This is essential because, if weeds or shrubs are allowed to grow, they can end up competing with the sédum and damage its growth.
Avoiding common mistakes on green roofs
Now that we know the most common mistakes, it is important to know how to avoid them when planning and executing a green roof.
Recommended types of waterproofing
Choosing the right waterproofing is essential for the long-term success of the green roof.
Opting for a bonded anti-root sheet, such as GreenMastic, can be an efficient solution.
This type of waterproofing protects against both water seepage and the damage that roots can cause.
The key is to make sure that the waterproofing layer is well laid and tested before proceeding with the next layers of roofing.
Characteristics of the ideal substrate for green roofs
The perfect substrate for a green roof must have the capacity to retain the necessary water for the plants, but also allow good drainage to avoid waterlogging.
Not all substrates are suitable, and as Jordi pointed out, ‘if we were to place one metre of soil, we could use any type of plant’, but in green roofs, the amount of substrate is limited, so its quality is crucial.
Native vs. exotic plants: which one to choose?
The choice of plants should depend not only on the local climate, but also on the intended use of the roof.
Native plants such as rosemary or lavender can be a good choice if you have sufficient substrate and are willing to do the necessary maintenance.
Otherwise, low-maintenance varieties such as sédum may be the best choice for extensive roofs that do not require intensive care.
Tips for an efficient irrigation system
Installing an automatic irrigation system can make the difference between a canopy that thrives and one that fails.
This not only ensures that the plants receive sufficient water during the dry months, but also reduces the thickness of the substrate.
A well-designed irrigation system ensures that the canopy is always in top condition without having to rely solely on natural rainfall.
These are the most common mistakes we have detected in our more than a decade of experience with green roofs.
If you have any questions about this you can contact us.
