Ventilated façades have been around for a long time. In traditional Scandinavian housing, for example, an air gap was included between the timber external wall and the internal wall, as a way of preventing these soft wood structures from rotting in a rainy climate. But the principles go back further than that – in fact, they take their cue from the natural world. By Trespa UK.
Throughout nature you will find protective membranes or skins. Animals, trees and even planets all have skins that protect their internal systems. Not only do these skins protect but they also act as mediums between the inside and the outside. Systems in these natural skins permit the transfer of certain elements such as vapour from one side to another, allowing them to ‘breath’.
Until recently most buildings have had sealed envelopes rather than breathable skins. Their primary function was to protect the indoor space from the outdoor environment. Sealed envelopes can cause problems for a building if they leak or if there is inadequate ventilation. Leakage can cause deterioration of the (inner) wall construction. Due to the inner wall being out of sight this leakage is often discovered too late resulting in costly repairs.
Today, ventilated façades are applied worldwide as an answer to allowing a building to ‘breath’. They enable architects to meet the requirements in different climates. By introducing a ventilated air space between the cladding and the construction, vapour can more easily pass between the skins of the building. This contributes to a healthy indoor climate.
A ‘breathable’ building
A number of benefits result from allowing the migration of moisture and vapour from the interior of the building into the open air. By letting moisture escape and stopping water penetration, the growth of mould colonies and rot is suppressed; mould can cause respiratory problems and even trigger asthma attacks. Wood rot and metal corrosion, meanwhile, can affect the stability of the structure.
By integrating or even adding a ventilated rainscreen cladding system to a building façade water penetration is minimised, the load-bearing wall is in good condition, internal air quality is improved and insulation can be increased and kept in desirable condition.
This is down to a ventilated air space between the cladding and the load-bearing wall. The air in the designed cavity will circulate due to air pressure differentials and thermal differentials over the height of the building. In a cold climate this causes the condensation water at the rear of the cladding to dry. In a warm climate the moving air will cool the inner layers of the construction, thus reducing the demand for cooling energy.