subject: How Rising Damps Occur [print this page] Rising damps usually happens in old buildingsRising damps usually happens in old buildings. It occurs when the water from the ground rises into and through the capillaries of the bricks and mortar of buildings. Over time, a musty smell will develop as more concrete is exposed to water. How high the water rises within the concrete depends on the brick and mortars pore structure, as well as their rate of evaporation. As compared to coarse pored material, masonries that consist of a great proportion of fine pores allow water to rise higher, as the water takes less effort to rise itself higher through a narrower space than a broad space.
What you see on building walls when rising damp happens is due to the contents present in the ground water, such as soluble salts, chlorides, nitrates and sulphates. When the ground water rises through the capillaries, the contents will follow along. However, the water would evaporate, leaving those salt contents behind. When rising damps occur often, this allows more water to enter and then leave more of their salts behind, becoming even more concentrated over time. Furthermore, since chlorides and nitrates are hydroscopic, meaning that they can absorb moisture from the surrounding, a greater salt concentration will attract a greater amount of moisture. This can be worsened if the weather in your area is often humid. And blocking the dampness with decorations is not a solution as they can be contaminated by the salts too.
In order to counter this, there are rising damp treatments available. Rising damp treatments typically consist of the installation of a chemical called DPC, which can be injected using special injecting equipments, followed by the process of replastering with some sort of salt retardant. Another alternative is to use a damp-proofing cream that is to be injected into the holes in the masonry. This simplifies the process as no replastering is needed.
