Penetrating damp is caused by rain water being absorbed by the porous outer skin of the wall and then soaking through the structure by capillary action to finally show up as wet patches or black mold on the inside. Winters are especially harsh on exterior wall surfaces such as cement renders and common bricks and over the years they become more porous and susceptible to water ingress from wind driven rain.
A small amount of penetrating damp in walls is not a problem. In fact, it is essential that some water is allowed into the wall and on average an external wall will have around 10% to 15% moisture content. This small amount of penetrating damp drops the temperature of the wall to ensure that the warm moist air inside is drawn through to the outside so that the house breathes and regulates the moisture levels in the home. This keeps us warm, dry and maintains a healthy ambient atmosphere.
Unfortunately, due to aging and erosion, older homes often face problems and external renders lose the ability to resist penetrating damp. Many old cement renders applied to exterior brickwork contained lime, mixed into the sand and cement, which meant it burnt into the brickwork and, therefore, lasted for many years. The problem when knocking off old cement renders is that the faces of the bricks have been burnt away and are ideal for penetrating damp. So, if you are having penetrating damp problems from poor brickwork, cracked or split wall render or peeling masonry spray paints, then call in the leading expert in the Melbourne area, Paint Melbourne.