The Issue With Rising Damp

Rising damp is the term used to describe the slow movement of water from the lower parts of a structure to higher areas. This very common problem is often seen in older buildings and homes and also in newer buildings that have not been constructed with a properly installed damp-proof course.

Rising damp happens when groundwater rises up through tiny cracks (or capillaries) in brickwork and masonry through a process known as capillary action. Rising damp is a serious issue that can cause damage to the building’s structural integrity as well as its aesthetics.

The severity of rising damp is dependant on several factors including the level of groundwater, the salt levels within the groundwater, the pore (or capillary) structure of the masonry materials (bluestone, brick, sandstone, mortar etc…) and the rate at which the water evaporates away from the surface of the wall. As with most building issues, the longer the issue is left unaddressed, the more damage is caused.

Occasionally this water permeation and creeping up the walls is referred to as salt damp – particularly in South Australia where the soil contains much higher salinity. On the western coast and eastern seaboard, it is usually referred to simply as rising damp but often has an element of salt-attack itself.

Modern buildings prevent rising damp through the use of a damp-proof course – a plastic membrane that is installed along the mortar line of a building to create a waterproof barrier from rising groundwater. Occasionally this membrane becomes damaged, therefore this issue can be seen in modern buildings and homes also.

How to tell if you have a rising damp issue

– Aesthetic indicators – these include blistering, cracking or bubbling of plaster or paintwork and tea-staining along walls, ceilings and flooring. 
– Erosion of binders in brick, stone and mortar causing structural loss to these materials.
– Loss of insulation within a structure. The thermal conductivity of a wet brick is approximately twice that of a dry brick. This increase of thermal conductivity increases the cost of heating or cooling a property.
– Any presence of water-tide marks along a wall or white salt deposits known as efflorescence.

What problems are caused by rising damp?

Rising damp can cause many structural and aesthetic issues for owners and may even have health implications. Structurally, rising damp can permeate timber structures and skirting boards, causing them to rot. Often the rising damp brings salts into the structure, leaving salt deposits to cause corrosion and deterioration through an issue known as salt attack or efflorescence.

Aesthetic implications of rising damp

Aesthetic implications are seen as peeling, bubbling and cracking of plaster and paint, water-tide marks that appear along the walls and efflorescence which is seen as the deposit of salt along the walls, ceilings or floors.

Health implications of rising damp

Damp conditions are also an ideal breeding ground for mould, which is increasingly being linked to significant health hazards and autoimmune diseases. The damp itself is also a factor for health conditions including asthma, allergies, cold and flu. These health implications are particularly of concern to multi-residential property owners or landlords who hold a duty of care to ensure the safety of their building for tenants.

The value of a property can be impacted significantly by the presence of rising damp due to both the structural and aesthetic damage that requires repair and also the cost of preventing further damage.

Methods of testing to remediate rising damp

A property qualified technician will perform a thorough series of testing to determine where the damp is coming from. Other causes need to be eliminated as these require separate remedial treatments. These other causes may include lateral dampness or condensation whereby the water tide marks are higher than one metre off the ground. Lateral dampness is an issue whereby soil, dirt or a garden bed is providing the wall with a source of moisture which is higher than the waterproof installation. Obvious cases where lateral damp might be an issue include buildings built into the side of a hill or cellars which are below ground level.