Rising Damp: Causes, Signs, and Effective Treatment Methods

Rising damp is one of the most devastating conditions to plague a structure, especially in older buildings found in Melbourne.

Left untreated, it destroys structures and causes health hazards. Though rare, it’s in your best interest to understand rising damp management if you live in humid areas, as it will thrive in wet and damp conditions.

You can proactively protect your property if you have a potential damp risk. The best way to deal with rising damp is by understanding its causes.

That will help in formulating the best prevention and treatment options for rising of damp, as illustrated in this guide.

Understanding Rising Damp

What is rising damp, and how does it occur?

It refers to the gradual movement of moisture from the lower to higher parts of a structure. This occurs when groundwater rises through capillary action through porous building materials like bricks and mortar. 

Rising damp is often classified among three basic types of damp; the other two being penetrating and condensation damp. It is a menace to older houses with poor underfloor drainage in wet and damp environments.

Recognising the signs of rising damp

For early detection and effective repair, it is essential to identify the tell-tale signs of this damp. Damp environments can be harmful, so do a thorough check even when you spot a little damp spot. Seek the help of a damp surveyor if the exercise is beyond your knowledge.

Common signs of this include:

1. Tidemarks and damp stains: One of the most common signs of rising moisture is the presence of tide marks, which appear as dark patches on walls.
2. Damp patches: If damp patches are visible along walls of a building, that’s concrete evidence of rising damp.
3. Damp and musty smell: Like other types of dampness, rising damp can also leave a structure smelling musty. It might also cause damp air in rooms with inadequate ventilation. However, no distinct odour can definitively indicate damp and rule out other potential causes.
4. Decaying skirting board or floorboards: Long-term exposure to rising damp without treatment can cause further problems, such as wood rot, manifesting on wooden surfaces like floorboards or skirting boards at ground level.
5. Delaminating wallpaper or paint: Rising of damp causes your walls’ moisture levels to rise, making them damp to touch, and leads to peeling wallpaper or paint.
6. Efflorescence: When water evaporates, it might leave visible white or yellow crystalline salt deposits in the impacted areas, which may indicate rising damp.
7. Black mould: If black mould appears on the base of the wall or around the skirting board but does not spread to other parts of the structure, that’s a dampness issue.
8. Flaky or bubbling plaster: If you notice crumbling plaster or powdery layers on walls near the ground floor, this could indicate that your home has a damp problem, possibly rising damp.

The impact of rising damp on buildings

Damps can affect the structural integrity of a building and also looks unsightly on walls. 

Rising water can cause a salt attack (otherwise known as salt damp) by depositing salt in building structures which causes corrosion and deterioration.

Damp conditions caused by rising damp leads to loss of structural integrity, especially in porous masonry walls and wooden structures.

Left untreated, this can cause aesthetic damage such as peeling, cracking, and bubbling paint and plaster.

It can also leave water-tide marks and cause efflorescence on external walls when ground-level water rises.

Health hazards associated with rising damp

Moulds thrive in damp environments, and their spores are the leading cause of respiratory allergy conditions. They can cause lung diseases, respiratory issues, allergies, and asthma.

Causes of Rising Damps

These are the common causes:

Groundwater and its effect on buildings

Rising damp can occur because of groundwater. This may occur when moisture from the ground pools around a structure’s foundation and eventually seeps inside through tiny cracks. 

When groundwater rises from the inside, it penetrates the walls of the building. Over time, continuous moisture in walls can result in mould growth, blistering paint, and wallpaper peeling.

Faulty Damp Proof Course (DPC): causes and consequences

A damp proof course (DPC) is a barrier installed in structures to prevent moisture from rising. However, the original damp proof may be ineffective in preventing rising damp if damaged, fitted incorrectly, or wasn’t installed. 

A defective damp course will not stop the damp, eventually damaging your structure. Faulty DPC can result from several factors, including age, deterioration, physical damage, or bridging by exterior materials like soil or render.

Capillary action: rising damp on internal walls

Capillary action might cause damp rise on internal walls. It facilitates a significant rise in moisture levels above the ground. The wicking activity diminishes the structural integrity of timber and masonry and causes deterioration to interior walls. 

Prevent and Treat Rising Damp

Preventing rising damp

The standard approach to preventing rising dampness in internal and external walls is to use an appropriate damp-proof barrier during wall construction. Today’s typical building practice uses bituminous material or plastic sheets to create an effective damp-proof course.

Proper drainage around your structure will help divert water away from its foundation. This includes sloping the ground away from the structure and keeping the gutters, downspouts, and drainage systems in good working condition.

You should also ensure proper ventilation and airflow to reduce condensation and moisture buildup.

Effective rising damp treatment methods

The most common and efficient method of treating this is to inject a water-repellent damp-proof cream or paste into the mortar bed joint of affected walls to create a repair damp-proof membrane. Superficial treatments such as repainting have no effect.

Treating rising damp on internal and exterior walls involves manual injection or pumping the cream into pre-drilled holes in the mortar. 

Upon entering the area, the cream will become a liquid, absorbing moisture through the porous brickwork. As it cures, it forms a waterproof barrier from penetrating damp and condensation. 

Similarly, it can be easily stopped by installing a silicone damp proof membrane to serve as the new damp-proof course.

However, this treatment of this is tedious and costly since it involves removing the bricks along the faulty mortar course to install a new damp-proof course. It can also negatively affect the wall’s structural integrity, particularly in old buildings affected by rising damp. 

Wrapping Up

Rising damp is a grave problem requiring immediate attention and remedial action. Understanding the causes, prevention, and proper treatment procedures can fix rising damp and maintain your structures’ integrity.

If you suspect an issue with rising damp in walls, have it checked by a professional. We at SQM Architects can help identify a damp problem on a building you’re about to purchase by conducting a pre-purchase feasibility study.

The study will pinpoint the potential rewards and risks of the property, valuable information for deciding whether to proceed with the acquisition or not.

Contact SQM Architects today for expert services and peace of mind.