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Green your facade to help dry wet walls

...hard to believe? It's true ~ facade greening can dry your damp walls! While it won't replace professional, modern building drying, it certainly helps. Take this into account when renovating an old building!

Street with grapevine-covered facades in Wechselburg / Saxony ~ 1890
Street with grapevine-covered facades in Wechselburg / Saxony ~ 1890

A trick from the old days

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 500 liters of water to produce 1 kg of dry matter (which equates to about 2 kg of wood or 10 kg of fruit)!


How do the roots dry a building?

The widely branching surface roots will suck up all the rainwater first, while the deeper roots search for any lower lying soil water. If an area is drying out, the roots will atrophy there, and other roots will grow towards the nearest available moisture source.


An argument for the monument authority

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...


Typical examples of old houses with green walls

What is striking about most of the examples is that there is no ‘tree disc’ or similar for watering, which in turn makes it clear that the plants in question get their water solely from underground.

Three grapevines at an old house in Diesbar-Seußlitz / SaxonyA cottage with an old grapevine, at the time of budding in spring, Freyburg an der Unstrut / Saxony-AnhaltOld half-timbered house on Lake Constance with vines, near Rickenbach / Baden-WürttembergDry walls were also important for wooden houses! ‘Black Forest house’ with greenery (probably vines), around 1900A very old, small wall fruit tree (pear), Dornburger Schlösser / ThuringiaSmall espalier pear in Moritzburg / SaxonyThree espalier fruit trees (pear), near Bad Sulza / ThuringiaPoirier en espalier sur une dépendance en bois, région du lac de Constance, Sipplingen / Bade-WurtembergFour espalier fruit trees (probably pear) on the gable of a farmhouse, near Rochlitz / SaxonyThe ‘Heilgeistkirche’ with an ancient, three-lobed vine (Parthenocissus ricuspidata), Stralsund / Mecklenburg-Western Pomerania