Green your facade to help dry wet walls

The walls of old farmhouses were at least always halfway dry as long as vine or fruit trees on the house walls prospered. We already know that a vine/tree will dry the ground searching for water, so... put that green on the wall and let it pull water from there. Climbing plants tend to have a drying effect on foundation walls, which in earlier times was a commonly used technique for the greening of buildings. For example, a single grapevine has to absorb and evaporate 300 liters of water to produce 1 kg of dry matter (which equates to about 2 kg of wood or 10 kg of fruit). In the case of green facades – that is, on warm walls – this figure is likely to rise to around 500 litres due to increased evaporation!

With their extensive network of surface roots, rainwater is initially drawn up, meaning that it usually cannot penetrate deep into the soil in the first place. Deep roots are then used to locate moisture further down. Vines have a particularly high ‘suction power’ or ‘root strength’, which has been measured at around 16 bar. By way of comparison: wheat only manages 10 bar. Vines are thus able to extract and draw water even from soil that is already largely dry. If an area has dried out, the roots there wither and grow towards a new source of moisture....

Green facades as a means of drying buildings – this can also be an argument to convince heritage conservationists to approve greening if they are reluctant to do so...