When a structure is damp proofed it has a barrier placed in the floor and walls which prevent moisture from passing from the outside of the building to the inside. This phenomenon is called rising damp. Damp proofing in Bristol consists of a damp-proof membrane which is added for the purpose of eliminating the possibility of damp; the materials used for this are sheets of plastic and copper. Cavity wall construction requires a damp course on both sides.
On common method of providing damp proofing in Bristol is to create what is known as a DPC, damp proof course. A DPC is a horizontal barrier in a wall. A solid cement floor can be similarly protected by laying a DPM, damp proof membrane.
Rising damp occurs regularly and must be prevented. Damp can easily penetrate porous building materials such as bricks and mortar. This porosity allows for the damp carrying nitrates to come up out of the ground along with chlorides. The ground salts allow for moisture to be sucked from the air which in turn causes damp to form in conditions of high humidity.
Modern homes that are built today are all constructed with damp proofing. The damp proofing that is commonly used is strips of plastic or slate. Other materials that can be used for damp proofing is copper strips, concrete or layers of sand under the slab flooring.
When walls are damp proofed, a thin layer of plastic is placed between a pair of building blocks. A damp proof membrane is placed below the floor slab and is usually a large sheet of polythene. Cavity walls have a damp proof course installed about eight inches above the finished grade. This height is deemed sufficient to stop rain from splashing and having a detrimental effect on the walls. The damp proof course is applied to both the inner and outer walls with the outer wall being above grade and the inner barrier well below ground level.
An alternative method of damp proofing is to use a single sheet of plastic which is angled. This plastic spans the interior cavity and slots into both the inner and outer walls. When this method is employed the plastic must be perforated so that moisture and rain water drains out of the cavity, if this is not done, then the omission may lead to rising damp.
Any rising damp allowed to stay in the walls can quickly lead to the formation of mould and mildew as well as fungus growth. As well as being a serious health issue, the rising damp can leave stains on the walls and if it comes into contact with wood, rotting and deterioration of the wood soon follows. Damp proofing in Bristol is a preventative measure.
