For decades, plants have overgrown the walls of buildings. This is mainly due to vines which can climb to heights with their tendrils or suckers to cling. However, it wasn't until vertical gardens led to a real revolution. They made it possible to unite architecture with nature. Their incredible advantage is the ability to cover complex, curved walls with a super lightweight structure. Green walls are also a variety of multi-species artworks.
There are several systems for building vertical gardens. However, all these solutions must meet the following conditions. Each system must be isolated from the wall with a waterproof material such as an EPDM membrane or PVC board. This insulation must be done very carefully and ensure 100% leakproofness. Another very important element is to maintain a ventilation gap of several centimetres between the structure and the wall to ensure adequate air circulation. It prevents the formation of mould and mildew and allows the thermal insulation to “breathe”. The irrigation system is an essential component of a vertical garden. It consists of a network of interconnected tubes that bring water and nutrients to the root system of plants. The whole system is usually fully automated and computer powered. The last extremely important element that is part of the green wall is its structure. Its purpose is to conceal roots, hide the irrigation system and keep pockets or panels with plants in place.
Based on the way of planting plants, green walls can be divided as follows:
- modular (panel) system
- felt system
- container system
Fig. 1 http://www.inzynierbudownictwa.pl
The felt system is based on hydroponics and this is what is used in Partica Blanca's projects. It is one of the simplest solutions. It takes advantage of the properties of mats made of synthetic fibres intertwined with each other, which have the ability to accumulate water. These mats are sewn together in such a way as to form individual pockets in which the plants are planted. The way the mats are woven allows the roots to grow between the fibres while providing constant access to moisture and air. Felt can also be replaced by geotextile – a biotextile with good tensile strength and
Felt can also be replaced by geotextile – a biotextile with good tensile strength and permeability. "Depending on the needs, biotextiles with different parameters can be used for green walls, selected for their suitability for a specific type of application. Their big advantage is that the seeds can already be placed in them during the material manufacturing process, and a properly selected synthetic material also prevents excessive moisture retention in the substrate."
Fig. 2: http://ogrodwertykalny.pl
It is possible to water the felt walls by hand. However, the drip lines from automatic irrigation are usually placed between the individual pockets. They deliver water with dissolved nutrients directly to the plant roots. Additionally, the irrigation system is equipped with moisture sensors and an indicator light showing lack of fertilizer.
This system is extremely lightweight, easy to install and maintain. If individual plants need to be replaced, there is no risk of damaging the structure and no need to dismantle it. Simply replace individual plantings and turn the irrigation system back on, and the wall continues to work flawlessly. The weight of the felt system allows walls to be installed on large and tall buildings.
Two types of modular systems are distinguished: those filled with substrate or special mineral wool. These solutions are very popular due to their versatility and quick, easy installation. The panels are usually made of HDPE plastics. An interesting and inexpensive idea is to use gabion baskets for this purpose, which form the supporting structure of the wall. However, for more demanding customers modules made of aluminium or stainless steel are available.
A requirement for making a vertical garden in the modular system is to build a supporting structure, to which the panels will be mounted. For this purpose, the façade must be protected with an anti-root waterproof insulation such as EPDM membrane. Then the omega-type construction profiles are assembled. The panels planted with vegetation are screwed to the profiles. The next stage of work is to install the irrigation system, which is placed between the modules. Finally, the frame is attached, which masks the mounting and structural elements. It can be made of any material, but it must be durable and corrosion-resistant. Aluminium, plastic, stainless steel, architectural concrete or properly impregnated wood can be used for this purpose. When carrying out the work, remember to provide a layer of insulation between the façade and the green wall. This allows the building wall to “breathe”.
Fig. 3: http://ogrodowy-maniak.blogspot.com
The components with plants are often planted several months in advance so that the plant material takes root and gives an immediate effect. In addition, preparing the planting in advance makes the plants more resistant and better acclimatised to the new conditions.
A special substrate, with which the panels are filled, is a mixture of aggregates such as expanded clay, crushed brick, volcanic lava mixed with peat and coconut fibres. This composition makes the prepared substrate more absorbent, non-compressible and relatively light (approx. 1400kg/m³). The substrates based on mineral aggregates have been used on green roofs for several years. Now they have also found their way into vertical gardens.
Selecting plantings for these requirements is quite difficult. The climatic zone of Poland causes many plant species to freeze with such a small amount of substrate. Therefore, the plants that have not survived are replaced with other more hardy varieties. However, to minimize plant damage due to frost, it is recommended to use the layer of substrate which is 15-25cm thick. The disadvantage of this solution is its weight, which reaches up to 80kg/sqm.
15-25 cm grubości warstwy substratu. Wadą tego rozwiązania jest jego waga, która dochodzi do 80 kg/m2.
Photo 1. Modular system made of gabions and filled with substrate. Private house in Wesoła. Author's materials.
Another modular system using the principle of hydroponics are the panels filled with special mineral wool. This solution is very popular due to its light weight (up to 50kg/sqm) and sterility. The occurrence of fungi, mites, diseases and pests is minimised here. This eliminates the odour that sometimes accompanies substrate components. This is an extremely important advantage, especially for interior walls, which are usually located in reception areas, lobbies or spa salons. An additional advantage of this solution is the ease of replacing damaged panels, which simplifies system maintenance.
Photo 2. A ready-to-assemble hydroponic panel with plants planted. Photo from the author's archive.
Photo 3. Hydroponic modules made of Zinco composite.
The third type of green walls are container systems also known as hybrid systems. This solution is rarely used, because it requires a lot of space, very solid structures and a lot of time to achieve interesting effects. The system is a cascade solution and consists in placing containers with plants on individual floors. Its implementation requires the construction of a special scaffolding. The container system is great for factories, shipyards or any other place where there are old, unusable structures.
An interesting example of such a solution is the MPO park in Neo-Oerlikon in Zurich, which was established in 2002. The inspiration for this project came from the site of a former engine and machine factory. A structure measuring (100 x 35 meters) was built in place of the building. It has four storeys with a total height of 18 meters with pots planted with climbing plants. The structure forms a giant pergola where cultural events, theatre performances and music concerts are held.
source: http://szwajcarsko.blogspot.com/
source: http://szwajcarsko.blogspot.com/
