2.3.2.4 Installation of the substructure
Most living walls have a substructure which ensures that air can move between the wall and the building facade. Substructures for external living walls are normally made from galvanized steel or stainless steel. Powder coated steel is not suitable as it does not have a long service life. Systems without waterproof panels require that a waterproof membrane is fixed to the substructure. This can be done using EPDM rubber film, expanded PVC sheets or extruded PE (polyethylene) sheets. EPDM rubber film is fixed to the substructure using special glue stripes and primer, while PVC and PE sheets are fixed using stainless steel screws.
If the hardness of the facade is not as expected it may be necessary to use anchors in the drill holes when fixing the substructure. Facades made of multiple-chamber hollow bricks need to have a special mesh cartridge inserted into the drill holes before being filled with epoxy cement glue.
Classic anchor for hard material like concrete, stone, marble, hard brick..
Special anchor for hollow bricks
Special anchor for hollow bricks with mesh cartridge and epoxy cement glue
Figure 1: Anchors for different walls Source: www.humko.si
Fixing wall anchor and vertical support profile
Vertical support profile Finished grid of stainless steel frame
2.3.2.5 Installation of different types of superstructure
When the substructure has been erected, it is then time to mark out the supporting profiles or holes or anchors for panels, gutters, pots, textile layers, troughs and similar.
a) Geotextile mats
Two layers of fleece are stapled to wooden or plastic boards on the wall. Stainless steel staples must be used because of the corrosive effect of fertilizer. The irrigation pipe is normally mounted at the top of the wall, behind the fleece layer, and a gutter is placed at the bottom to collect surplus water.
When both the fleece layers have been fixed to the wall, U-shaped pockets are formed with a stapler, and the front fleece layer is cut at the top of each pocket. The pocket is left empty for hydroponic systems, or filled with sphagnum, mineral substrate, compost or peat for semi-hydroponic systems.
b) Plastic containers: modular panels
Modular panels for living walls can be made of different materials and in different shapes.
Normally they have a front and a back layer of PP, ABS or other composite, polystyrene, aluminum, stainless steel sheets, ceramic, gabions, etc. An average panel thickness is 6-15 cm, but some systems
are as much as 20-30 cm thick, which makes them very heavy to handle. Each panel has a hanging system, such as hooks, which are attached to the substructure and secured with screws.
Figure 2: Different modular green wall panels with different planting system Source: www.humko.si
c) Plastic containers: pots and troughs
Pots are fixed to a substructure such as an iron grid or plastic gutters. On a grid each pot requires its own drip emitter, while pots in plastic gutters soak up water from the gutter through holes in the bottom of the pot. Troughs are similar to pots on a grid system, but the containers are larger which allows bigger plants to be grown, such as climbers, shrubs or large perennials. Irrigation is much easier because fewer drip emitters are required, and the water distribution is more equal because of the larger substrate volume. The substrate must have mineral stone additives for good drainage and a high water holding capacity.
Figure 3: Different potting systems for green walls Source: www.humko.si
Vertical troghs Plastic troughs Inox troughs from the picture above
Figure 4: Different green walls systems Source: www.humko.si
d) Plastic containers: Self-standing living walls and partitions
Smaller mobile living walls can be used for temporary greening in restaurants, hotels, offices etc., and can be moved around as needed. They have small pumps and controls with a small water tank for irrigation.
Stand alone, mobile green wall Double sided mobile green wall
Figure 5: Self standing green walls, partitions, wall green tapestry Source: www.humko.si
e) Other systems i) Natural moss walls
The moss must be pre-grown in blankets, which takes 3-5 years. Moss blankets must be placed only in shadow, away from solar radiation. Waterproofing membrane, such as PVC or PE sheets, and irrigation sprinklers first need to be installed on the wall. The moss blankets are then nailed to the waterproofing mebrane. Moss walls can also be established by spraying a mixture of moss fragments, yoghurt and beer onto the wall. Moss walls need constant moisture, so they need to be sprayed with demineralized water every few hours during the day. If there is not a supply of rain water to irrigate the wall, small reverse osmosis filters can be installed which remove dissolved inorganic solids from tap water. No fertilizer is needed; indeed, iron fertilizer will kill moss within an hour.
Figure 6: Natural moss walls Source: www.humko.si
ii) Preserved plant walls
Preserved plants are not living plants, even though they look like they are. Moss and plants are glued to the wall with a glue gun or nailed with staples. Many combinations of moss and plants are available in different colors. Preserved plant walls do not require irrigation, sun, or any maintenance. The lifetime of preserved plants is 5-10 years.
Figure 7: Impregnated moss walls Source: www.humko.si
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